Sildenafil Dosages, Uses, Side Effects, Mechanism of Action

Sildenafil Dosages, Uses, Side Effects, Mechanism of Action

Sildenafil Dosages, Uses, Side Effects, Mechanism of Action

The appearance of sildenafil in the pharmaceutical market was a world breakthrough. Being the first remedy for the professional treatment of erectile dysfunction in males, it has saved many families and relations. What do users love sildenafil for? Is this legendary drug really magic? Let’s speak about sildenafil characteristics and its analogues.

Viagra is a top product of the Pfizer multinational corporation. In 2016, Viagra generated 1.56 billion USD of revenue. This drug has been in the pharmaceutical market for 19 years and still has not lost its selling position.

It is the most frequently prescribed medication for men with sexual dysfunctions. Multiple generic producers struggle hard to let Viagra copies enter the global pharmacy.

What Is Sildenafil?

Sildenafil is a chemical ingredient which is used for the treatment of sexual dysfunctions in men, caused by abnormal natural processes in the organism. It belongs to the PDE5 inhibitors drug family, the main principles of which are relaxing muscles and forcing blood circulation to particular body areas. Among erectile problems, this chemical cures pulmonary arterial hypertension (high blood pressure in lungs).

Sildenafil is manufactured for males and females in different product lines. Female products are used for treating sexual problems in premenopausal women and boosting libido. Its effect on women was discovered later and this subject is still undergoing scientific research.

Sildenafil is produced under multiple brand names. One of the most well-known is Viagra, through another famous brand name is Revatio. They all contain sildenafil in different dosages.
Sildenafil Dosages, Uses, Side Effects, Mechanism of Action


The familiar «blue magic pill» has a riveting history behind its invention. In fact, Viagra developers intended to create a drug for cardiovascular illnesses. In 1991, Pfizer concern workers tailored a chemical substance which belonged to the pyrazolopyrimidinone class and it was purposed to cure heart diseases (angina, chest pain, etc).

During the clinical researches under the leadership of Ian Osterloh, the significant effect of sildenafil in the treatment of the mentioned diseases was not found. But they examined an unexpected adverse symptom: improving and sustaining erection in males. Pfizer stopped heart illness investigations and concentrated on further research in penile erection.

Viagra pills

The names of the Pfizer Viagra inventors is a big secret that every worker of the company should maintain. At first, the British press was given the names of Peter Dunn and Albert Wood as responsible people for inventing the process.

Later in the same year, Andrew Bell, as well as doctors Nicholas Terrett and David Brown, proved the efficiency of sildenafil in an angina cure. Terrett was named in the patent document for the practicing of sildenafil in heart illness therapy, and he is known as «Viagra’s father». He says that indeed his command has discovered the genuine assignment of sildenafil, while P. Dunn and A. Wood developed a method of mass-producing it.

In 1994 continuing heart problems investigations, Terrett and his coworker Peter Ellis observed the working mechanism of sildenafil. A. Wood and P. Dunn continued working on the chemicals, too, taking part in a 9-step process to synthesize sildenafil into a pill. On the 27th of March, 1998, sildenafil was approved by the FDA.

Pfizer has not rewarded any particular inventor of sildenafil from the working command. Following the information that was given to American Press, Viagra’s inventor was recognized as the Senior Vice President of Medicinal Discovery of Pfizer, Dr Simon Campbell, who was responsible for the developmental process.

The Viagra product was a real booster of Pfizer income. Its profits have risen drastically after bringing the «blue pill» into the world pharmacy market.

In 2013, the Pfizer patent on Viagra ended in the countries of the European Union. That fact allowed generic producers to manufacture their own variations. They have been using the name «sildenafil» for their drugs, since the name «Viagra» can be used by Pfizer only. Therefore, today the pharmacy market can offer to ED sufferers both the original Viagra product of Pfizer production and multiple generic remedies which contain sildenafil and are characterized by equal action.

«The little blue pill» is a name peculiar to the Pfizer product only. Its generic copies are usually white and round. This visual difference of the tablets does not imply diverse medical characteristics. To receive market approval, generics must be absolutely bioequivalent to the branded drugs, as well as prove safeness and identical effectiveness.

Is It FDA Approved?

Production of sildenafil

Viagra is the first oral drug in the USA approved for impotence treatment. Sildenafil was marked as Viagra and Revatio, and it was originally approved by the FDA in 1998 and has been distributed in 120 countries. The original Pfizer patent will expire in 2020.

But there is an exception for a few companies. Based in Pennsylvania, Israel transnational Pharmaceutical Industries Teva has settled an agreement with Pfizer. In fact, Teva had been selling generic sildenafil since 2013 in Europe and had long court procedures with the original producer of «little blue pill». According to the agreement document, Teva company was allowed to produce generic sildenafil, paying a royalty to Pfizer through the expiration of the Viagra patent in the US. Generic sildenafil of Teva’s production has been launched since December 2017.

Mylan, one of the world’s leading generics and specialty pharmaceuticals company, has also created an agreement with Pfizer not to release their generic Viagra version until 2017.

At least nine generic producers have applied to the FDA to approve their version of Viagra. Successfully checked products will be able to participate in the global pharmacy market in 2020. Meanwhile, generic Viagra is available and has been successfully sold in Canada since 2012, and in European countries since 2013. The companies Teva and Actavis debuted generic Viagra in Europe.

Sildenafil Brands

The first patent expiration of Pfizer product ended in June 2013. That period was a party time for generic producers. According to data from The Guardian, approximately 20 generic drug makers lined up their version of generic sildenafil. Among these companies are:

  • Sandoz (Novartis company and a global leader in biosimilars);
  • Teva (multinational pharmaceutical company);
  • Accord (young and fast growing generic pharmaceutical industry in the UK and Ireland);
  • Ajanta (Indian multinational company);
  • Dr Reddy’s (Indian multinational pharmaceutical company);
  • Mylan (American global generic and specialty pharma registered in the Netherlands);
  • Actavis (global company that specializes on generic, over-the-counter drugs, and biologic products);
  • Torrent (the leading pharma of the Torrent Group, based in India);
  • Bristol Labs (young and fast growing British drug producer that specializes on generic medicines in Europe and the UK);
  • Zentiva (European manufacturer of modern high quality generics);
  • Ratiopharm (German pharmaceutical generics business);
  • Ranbaxy Laboratories (Indian multinational pharma industry);
  • Neuraxpharm (German manufacturer of generic medicines);
  • Cipla (one of the top global pharmaceuticals companies in India).

Sildenafil brandsRegardless of the brand, the molecular structure stays equal, as well as the absorption method, mechanism of action, side effects, and action of the metabolism. Color, shape, size, and consistence may vary, but these features do not impact the main principles of the drug’s work. The pills with the same strength but produced under different brands are very much like one another due to containing the same amount of each chemical agent. Licensed by the local government, products have passed the quality and safety tests which the state law demands. The scientific studies between drugs with the same dosage of active substance but produced by different manufacturers are absent and unnecessary.

As is so often the case, drugs go out of stock and that causes a big concern in patients. Absent of a particular medicine may happen because pharmaceutical companies cannot fill the wholesale orders from pharmacies or the drug was manufactured in small batches. No matter what the reason is, usually people get used to one trade name and are quite skeptical in situations when they need to switch to another. There should not be any fear though, as when choosing a licensed drug, a patient will guaranteedly get the promised effect.

Viagra and Generic Sildenafil – What’s the Difference?

Today the pharmacy market offers the original Pfizer Viagra and generic sildenafil in multiple form and dosages. The first thing which catches attention in the Viagra vs generic sildenafil battle is definitely the difference in costs. Generics’ prices are a lot cheaper (15-90%). The reasonable patient’s question is what is the difference between the two drugs and if the original Pfizer product is worthy of the money the manufacturer requires. Let’s check the factors that define the sildenafil and Viagra difference:

  1. Composition. The brand Viagra and generic sildenafil contain the same active substance, sildenafil. The minor compounds of the pills may be different, but it does not affect general drug’s work. Identical chemical structure guarantees the same working mechanism.
  2. Effectiveness. The vast majority of patients assume both drugs are equally efficient. Only a small percentage of users find the original product more powerful.
  3. Side effects. Most patients experience the same adverse events after taking the original and generic products. A very small number of males experienced different negative reactions after taking a generic interpretation. This fact may be explained by the different minor compounds.
  4. Price. As stated above, generics cost much less. A pharmacy coupon can help to economize, too.

This comparison is true only for generic preparations which were produced by reputable companies. Patients should avoid products of unknown manufacturers without a quality certificate attached. Mislabeled drugs may not provide the promised effect and make a damaging impact on the consumer’s health.

Difference Between Sildenafil and Sildenafil Citrate

SildenafilPatients may see the term «sildenafil citrate» and get concerned about what is the difference between sildenafil and sildenafil citrate. Sildenafil citrate is the patented active ingredient which Viagra has. Sildenafil is the short name of long Viagra chemical formula. Viagra’s medical subject headings (MeSH) are defined as:

  • citrate, sildenafil;
  • homosildenafil;
  • lactate, sildenafil;
  • acetildenafil;
  • desmethyl sildenafil;
  • hydroxyhomosildenafil;
  • NCX-911;
  • 1-((3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo(4,3-d)pyrimidin-5-yl)-4-ethoxyphenyl)sulfonyl)-4-methylpiperazine citrate.

It means that definitions «sildenafil» and «sildenafil citrate» are synonyms.

Dosages of Sildenafil

The original Pfizer sildenafil comes in three doses: 25 mg, 50 mg, and 100 mg. The most convenient and frequently recommended one is 50 mg. It is a moderate dosage which can be decreased to 25 mg in case of annoying side effects, or increased to 100 mg in case of weak effect. Regardless of the amount of sildenafil, one dose must be taken only once a day. Increasing the dose independently without medical consultation is strongly forbidden due to individual health conditions and high risks of unwanted reactions.

The generic doses are designed for maximal customer’s convenience. There is sildenafil in dosages 20 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg, and 200 mg. The dosage of 100 mg is the most frequently used among customers due to good effectiveness and moderate side effects manifestations. Low sildenafil concentration (20 mg, 25 mg, and 50 mg) will be good for light sexual problems. Respectively, the doses 150 and 200 mg are recommended for the treatment of severe erectile dysfunction (ED) cases. They can be used if the lower dose 100 mg was well tolerated but showed weak effect.

The correct plan of cure must be prescribed by a healthcare provider in private order based on the patient’s general health condition and the level of current erectile problem. The doctor should estimate the important factors and state what is the normal dose for each particular case and how to use it.


Injections of sildenafilModern pharmacology offers sildenafil in multiple medical forms which makes the usage easy and convenient. The available products are represented in the list below:

  1. Classic rigid tablets. Film coated, not chewable drug that should be used along with a full glass of water. The form and color may vary depending on the manufacturer.
  2. Sublingual tabs and troche. The tab should be placed under the tongue and dissolved without water. The benefits of this form are a faster onset of action with a smaller dose plus quicker work of the drug due to quick absorption. It should be noted that this drug form is not approved by the FDA and is assumed as off-label preparation which may cause severe side effects.
  3. Effervescent dissolvable tablets. This is a unique formula of the tab which should be dissolved in the water to provide easy absorption and even more effect. Quick solubility and a delicious taste makes it easy to consume.
  4. Oral jelly. The remedies that look like a tasty dessert will be estimated by those who can not stand bitter rigid drugs or have difficulties with swallowing firm medicines. Various choice of tastes and consistency turn the medicine usage into fun which can be played in sex games with your partner.
  5. Capsules. Quick dissolving in the bloodstream, these capsules provide an awesome effect: capsules start working in 20-30 minutes.
  6. Liquid (oral suspension). Mainly used for curing pulmonary hypertension in kids.
  7. Topical cream. This unique formula will be especially estimated by those who cannot take sildenafil orally due to side effects or health conditions (angina or heart attack patients). The cream should be applied to the tip of the phallus. Once it is absorbed into the skin, the erection appears. Applying creme directly to the genitals diminishes side symptoms such as headache or dizzying and solves the specified erectile problem. This form is not approved by the FDA yet and is still in the developmental stage.
  8. Injections. The solution for injections is meant for the treatment of pulmonary arterial hypertension (PAH) in adults and those who cannot take oral drugs. 10 mg of injection equals 20 mg of the oral dose.
  9. Powder for oral solution (Sildenafil Mesylate). The form allows rapid absorption due to its dissolving in water for suspension making. Powder is also widely used for PAH treatment.
  10. Vaginal tablets. Used for improving uterine artery blood circulation in women undergoing in vitro fertilisation (IVF).

The variations of sildenafil are multiple, and the drugs may be named differently. It exists in the pure state and in combination with other ingredients. A patient should pay attention to the active ingredients. Mixed preparations contain different doses of the chemical agents. A few examples of pure and mixed sildenafil are represented in the table.

Pure sildenafil In the mix with the ingredients

Cenforce, Super P-Force (Viagra Super Active, sildenafil and dapoxetine)


Malegra-FXT, Viagra Super Fluox-force

(sildenafil and fluoxetine)


The strength of the drugs vary, too. There are enhanced formulas of pure sildenafil (like Sildenafil Professional) which have a longer time course and prolong erections up to 6-8 hours, providing an even more powerful effect.

There is also a special line for women that cures female sexual arousal disorders and helps females to achieve orgasm. These drugs showed good results during clinical trials, though the proper scientific research goes on.

Who Can Use This Medicine?

Cases of uncommon sildenafil usesViagra is a famous medicine for men with ED problems. Along with sexual dysfunctions, it can help with other ailments, too. The medicine can be taken by males and females, and it is cautiously used in children. The science news registered the following cases of uncommon sildenafil uses:

  1. Diabetes and gastroparesis. Scientists of Johns Hopkins Medicine in Baltimore, Maryland discovered that by relaxing the stomach tissues, sildenafil helps to prevent digestion process slowing, anorexia, and dehydration.
  2. Altitude-related lung disorders (altitude sickness). German scientists found out that alpinists who received a dose of Viagra could endure a lack of oxygen in the Himalayan mountains.
  3. Angina attack. Iceland academic researchers ascertained that sildenafil may disable the gene that prevents blood vessels from widening and leading to a major stroke risk.
  4. Cardiac distress. Due to widening blood vessel function, sildenafil allows physical exercising and sexual activity to normalize blood pressure and heartbeats.
  5. Female sexual disorders. Sildenafil helps to stimulate bloodflow to the female genitals, increasing sexual satisfaction during intercourse.
  6. Sterility. An overly thin uterine lining is one reason for female sterility. Sildenafil allows the enlarging of the uterus lining through dilation of the blood ways.
  7. Premature birth. England doctors gave sildenafil to a baby born on the 24th week of pregnancy. That helped to open arteries for heart treatment through the pulmonary artery, excluding lung disease.
  8. Pregnant women who suffer from intrauterine growth restriction (IUGR), a state when a baby in the womb does not develop normally. The retardation of fetal growth may cause various problems during the pregnancy or after birth. Increasing the bloodflow in the genital area, sildenafil may help by supplying more oxygen to the placenta. The studies go on.

Sildenafil for ED

Sildenafil is widely used in ED treatment for men. The American Urological Association recommends first to deduce the reasons which caused the erectile problems. They may be a sign of diabetes or cardiovascular diseases, particularly heart or blood pressure problems. Depressive states and problems with partners may also impact sexual ability. A patient should bear in mind all the drugs he has been taking. Some antidepressants, heartburn and blood pressure medications, or analgesics may cause ED as an adverse symptom.

When the ED problem is diagnosed by a urologist, a patient can apply for sildenafil therapy. Its efficacy and safety has been tested in numerous studies, and it is the most frequently prescribed drug since its side effects have been studied in detail.

Discovering the nature of ED in a patient is very important for successful treatment because Viagra’s action does not cover physiological states. It is somewhat helpful in stressful conditions and boosts the feeling of self-confidence in a man. But sildenafil does not cause sexual desire, it only helps to achieve and maintain an erection.

Many males all over the world have had an effect from Viagra and widely use it for random or regular treatment. Those who might get information about Viagra from unofficial sources may dismiss it as a lifestyle drug or one with little medical importance. In fact, this is a serious medication which should be prescribed for individuals. It works on the phallus arteries and may provoke various side effects. Therefore, a personal healthcare provider recommendation is necessary.

Is It Used for Pulmonary Hypertension?

Pulmonary hypertensionPAH is a group of diseases in the narrow state of arteries which transport blood from the heart to the lungs which is characterized by heart overwork. It may lead to right ventricular failure and premature death.

The function of sildenafil consists in relaxing the arterial muscles and broadening the arterial channels. The result of the therapy is easier bloodflow, proper supply of the lungs, and improved ability for physical activities.

Pediatric use of sildenafil caught close medical attention. During a small clinical trial, 14 kids aged 1-17 y.o. with PAH were tested. After 6 months of usage, the walking distance increased (which proves an increase in physical ability), without major adverse symptoms. The allowed doses of sildenafil in kids are low (10 mg) and medium (10-40 mg).

In August 2012, the FDA announced a strong warning against using sildenafil in children, justifying this by the high level of mortality in kids after high doses and ineffectiveness of low ones for PAH therapy.

In response, clinical pediatric PH experts put forth a consensus statement with cautious use of low and moderate doses of sildenafil in children and strong warning to avoid high ones.

The problems of sildenafil for PAH therapy today is a lack of evidence, despite several experimental reports and numerous medical articles. The medical community eagerly waits for more clinical studies and answers for the questions of whether or not sildenafil can be used in long-lasting therapy and which doses are recommended. Generally PDE5 inhibitors appear to be an attractive and effective addition for curing this devastating orphan illness.

Sildenafil for BPH

Many men face erectile and large prostate problems at the same time with age. These diseases are caused by different issues, though in some cases the therapy of BPH may cause ED. Scientific research has proved that effective ED drugs, including sildenafil, may have a powerful positive impact, reducing the symptoms of BPH.

The meaning of sildenafil in the BPH cure has been studied for four years. The prostate is a gland at the base of the bladder which is responsible for producing spermatic fluid. When BPH starts its progress, a patient has urination problems. Sildenafil helps to relax muscle cells, making urination easier.

During clinical trials of the most popular ED drugs, sildenafil, vardenafil, and tadalafil were checked in 1000 men with average and severe forms of low urinary tract symptoms over 8-12 weeks. Daily usage of PDE5 inhibitors have had a positive impact upon results. ED therapy in BPH is assumed to be safe and effective.

It should be noted that long term usage (6-12 months) and interaction between ED and specific BPH drugs demand more scientific research. As far as the parallel intake of alpha blockers and ED drugs may significantly lower blood pressure, the combined therapy should be elevated. The costs for ED drugs are not covered by insurance for BPH treatment, and that factor should be counted as well.

Can Sildenafil Be Taken Daily?

SexPatients with chronic ED may wonder, can sildenafil be taken daily? For Viagra, a 25 mg is a dosage appropriated for daily usage. Usage of sildenafil on a daily basis has gathered contradictory opinions. Some scientists claim that there is no need to take it if a patient does not have sex every day. Sildenafil does not possess accumulative features and does not recover the phallus tissues but only stimulates them to plan for very soon sexual intercourse.

Moreover, daily usage may cause psychological dependence. Without sexual stimulation, chemical processes after taking sildenafil do not happen, but a man starts to feel more confident. If a man think, that only this drug makes him sexually strong, it can lead to emotional dependency.

According to the opinion of professor Irwin Goldstein of Boston University, daily Viagra usage is a good preventive course from possible ED problems. It is based on a small study during which 30 men used a small dose of sildenafil every night and marked the awesome effect of it. The international medical community has highly criticized this point of view.

The effective drug approved for daily usage may be called Cialis (tadalafil), available in 2.5 mg and 5 mg. These doses have multiple advantages: acting within 15-20 minutes after consumption and maintaining a positive effect up to 36 hours. It is well-tolerated and compatible with alcohol and does not cause addiction.

As a whole, daily usage of Cialis also helps to:

  • overcome premature ejaculation problem and increase libido;
  • struggle with bacterial and infectious agents;
  • increase viruses resistance;
  • improve blood vessels condition;
  • normalize testosterone production;
  • improve the quality of seminal fluid;
  • restore microflora of the genitals;
  • prevent unexpected stress.

Is It Safe?

ErectionMultiple assessments dedicated to the question is sildenafil safe were all successful. During one of the trials, 1008 patients with ED dysfunction were recruited and received doses of 25-100 mg during 36-52 weeks of studying. In 36 and 52 weeks, 92% and 89% of men had felt improvement.

In results all criteria were marked, such as the duration of sexual intercourse, rigidity of erection, general level of satisfaction, and the frequency of stimulated erections. Among the most common adverse symptoms noted were headache, blushing, upset stomach, and nasal problems in soft or moderate form. Long lasting therapy does not detract the effectiveness of sildenafil in patients with ED.

The clinical trials warn that sildenafil should be cautiously used in cases of heart failure or acute myocardial infarction or stroke diagnosticated up to 6 months ago. Parallel use of nitrates containing drugs (glyceryl trinitrate, isosorbide dinitrate) is unsafe. Sildenafil is perilous for patients with unstable angina pectoris. In the absence of contraindication, sildenafil is extremely suggested for ED cure.

Existing evidence proves high effectiveness and well toleration of sildenafil in males with ED and spinal cord injury, urinary tract symptoms benign prostatic hyperplasia (BPH) with concomitant ED, and for pulmonary hypertension cases in severe form (including children). Uses for women demand more scientific research.

How to Take Sildenafil Pills for the Best Results?

Sildenafil is an effective, powerful, and well-tested drug which improves ED problems in most cases. Those who did not feel its effect obviously have made several mistakes in therapy course. To achieve the best results from the medicine, it is extra important to have a clear understanding about how to take the pills correctly. To receive the maximum effect from the drug, ED patients should avoid the most common mistakes that cause the failure of the drug:

  1. Lack of information. 69% of patients do not receive a proper medical consultation before starting the treatment course. Sildenafil must be used only after a complete medical examination of general health condition at a medical center and receiving an individual prescription. The healthcare provider should tell a patient detailed instructions: what is sildenafil, how it works, when to take, and how to take it. The drug should be used strictly in correspondence with the given directions.
  2. Lack of sexual stimulation. Do not expect a miracle to happen. 3% of males still think that after taking the «magic blue pill» the erection appears in a simple way. That is a false belief. Sexual mood and stimulation are the necessary factors that activate the chemical processes in the organism, leading to the erection. Without foreplay, touches, tastes, and smells, reaching sexual excitation and a rock hard erection is impossible.
  3. Low dose (happens in 31% of patients). Doctors usually prescribe a minimal dosage in the beginning of the course to reduce side effect manifestations. Sometimes it is enough for treating ED, sometimes it is not. In case a patient did not feel the effect, it makes sense to talk to a medical representative about increasing the dosage (if the patient’s health condition allows that). Taking an enlarged dose independently is prohibited and risky due to unwanted negative reactions.
  4. Taking the drug after a meal. Over 20% of the head counts showed that patients take the drug after a square dinner. In fact, the drug works best on empty stomach or at least after a light snack. That is caused by the indigestion process which slows down how sildenafil works. Those who have had a good feed should wait to take sildenafil for 2-3 hours.
  5. Let the drug start working. Eager patients should remember that the remedy starts working within an hour after consumption. Some sildenafil versions start working sooner, in half an hour or so. Nevertheless, there should be a time period before consumption and sexual act. Do not hurry up; use your spare time advantageously for fantasies, sexual conversations with your partner, and foreplay!
  6. Test a few dosages. It often happens that sildenafil does not work the first time. But 33% of males stop taking the drug after the first failure. A patient should not lose hope and take more doses later according to the treating scheme up to 5-6 times, remembering that the next consumption might be taken in the next 24-hours period.
  7. Try another drug. Every patient responds differently to the medicines. If all methods mentioned above appeared ineffective, that does not mean that this ED problem is an incurable disease. It makes sense to try other pills of identical action but with a different active ingredient, for example Levitra (vardenafil) or Cialis (tadalafil).

What Happens if I Overdose?

Watch carefully how much sildenafil you consume. If the sildenafil dosage was taken high in value, the symptoms will be seen within few hours after the drug consumption. Usually they are manifested as side effects.

Blurred vision

Among the most common overdose reactions are:

  • sudden blood pressure drop (high or low) which leads to fainting;
  • priapism (abnormal long-lasting erection during 4 hours and more);
  • blurred vision or sudden loss of sight;
  • abrupt hearing loss;
  • complications from the side of kidney and/or liver work;
  • bleeding;
  • physical deformation of the secondary sex organ and permanent impotence;
  • stroke or heart failure.

The need for medical intervention depends on the manifestation of the side effect and how long does it last. In case of rapid negative health changes, a patient should contact local hospital personally for emergency treatment immediately. The therapy of sildenafil overdosing may be different depending on the situation. The intensity of the symptoms might be lowered by other drugs or medical methods.

It is always better to exclude such incidents by following the rules and a dosing regime of sildenafil consumption. Do not start taking sildenafil if your health condition does not allow it.

Sildenafil Mechanism of Action

To better understand the purpose of sildenafil and how does it work for ED, it is necessary to know how an erection appears. The penile erection is defined as a state caused by blood pressure which flows to the phallus, enlarging it and providing rigidity. An erection may appear in sleep and awaken a man’s condition.

For successful penetration, the phallus must be erect. In healthy men, the nervous, arterial, and vascular systems are in order, so a man easily becomes erect after sexual stimulation. For men with ED problems, achieving erection appears to be complicated. And Viagra is able to help here.

Since massive bloodflow to the penile area is a necessary condition for an erection, the function of sildenafil consists in increasing blood circulation to the genital area. When a man is in a sexual mood, his brain sends messages through the nervous system and blood starts flowing to the phallus. Patients should remember that Viagra is neither an aphrodisiac nor a hormone. A single tablet without sexual stimulation is helpless.

The psychological factor is very important in the mode of action because it impacts many chemical reactions in the organism. When a man is aroused, his body starts releasing nitric oxide in the erectile tissues, the two parallel changes at the sides of the phallus. Nitric oxide, in turn, brings into action the ferment guanylate cyclase, increasing levels of cyclic guanosine monophosphate which is responsible for erectile function.

Belonging to the PDE5 inhibitors class, sildenafil blocks the chemical phosphodiesterase type 5, which prevents a healthy erection. Among blood flowing, sildenafil intensifies the effect of nitric oxide by blocking PDE5 and increases the levels of cyclic guanosine monophosphate. As a result, the smooth muscles of the phallus receive enough relaxation and proper bloodflow, the excellent conditions for an erected state.

Understanding the action is not enough, and every patient should know how long does it last. The drug has an elimination half-life of 4 hours (working time) and 5.5 half-lives. This means that one dose of sildenafil stays in your system approximately 22 hours in a whole. The elimination period depends on such individual features as age, food, alcohol consumption, general health state, taken dosage, and much more.


High popularity of the famous Viagra has changed to abuse in the past few years. It happened mostly because of men ignoring the rules of sildenafil administration, and, as a result, side effect manifestations in them.

Viagra is not «magic» for everyone, as contraindications still exist. There are categories of males who cannot use this drug.


Among them are males who:

  • have not reached the age of 18 y.o.;
  • are prohibited to have sexual life due to weak cardiovascular health;
  • have circulatory system problems (thrombocytopenia, leukemia, hemophilia);
  • consume nitrates, organic nitrites and nitric oxide donors;
  • suffer from hepatic and renal ailments in severe form;
  • experience hypotension or hypertension;
  • have had heart attack or stroke during the last 6 months;
  • suffer from retinal diseases;
  • have long-lasting and painful erection (priapism) propensity or phallus deformity;
  • sustain bleeding illnesses.

Highly allergic individuals should be very cautious while taking sildenafil, because it may cause negative reactions or chronic poisoning complications.

The list of diseases is represented for review and is far from complete. Consult a private healthcare provider regarding every particular medical condition.

Sildenafil Side Effects

Most drugs cause side effects, and sildenafil is not an exception. Clinical trials report about mild and average unwanted reactions. Severe forms of side effects are registered rarely. The table represents the classification of the most frequent adverse events.

Major symptoms Minor Symptoms
Common Rare Common Rare
Urinary bladder pain Severe and / or counting migraine Muscles ache Pain in stomach or abdominal
Disturbance Cough
Behavior changes similar to alcohol intoxication Disquietude
Gibberish speech Pursiness Bleeding from the bottom
Muddy or bloody urine Concentration difficulties Nightmares
Frightening dreams Blushing
Urinary frequency Broken sleep Earache
Dizziness, especially when getting up suddenly from lying or sitting Urination at night
Chilling Oversensitivity of eyes and face bones
Painful urination Ague Sickness
Feebleness Entotic sounds
Fatigue Sneezing
Eye bleeding
Heat sensation in stomach or chest Weak vision Increased salivation
Blurring of vision
Blue vision Difficult swallowing
Ambiopia (double vision) Bloody nose
Eye dryness
Dyspepsia Eye ache Stomach cramps
Sensation of something in the eye
Eye redness, itching Sore head Puke
Shades of colors
Light sensitivity
Vertigo Temporary loss of sight Tongue redness or irritation
Bone pain
Hands numbness Digestive trouble Limbs numbness or tingling
Lower back or side pain
Swollen joints
Numbing Muscles twitching Sore mouth, lips
Cramps, seizures Nasal congestion or runny nose
Excessive hunger Hypersensitive skin
Itchiness Fast, irregular heart rate Shaking
Hard breathing Warm skin
Sore throat Drowsiness
Loss of hearing
Pale skin
Prickly sensation Skin rash, itch Poor sleep Orgasm failures
Ulcers on skin
Cutaneous lesion Asthma exacerbation
Skin stinging
Long-lasting painful erection

Not all medical states from the list above require medical help. Most side effects disappear as soon as the body gets used to the new drug. A medical representative may suggest methods of avoiding unwanted reactions.

If the events are continuing and bothering, medical consultation is highly recommended. After a medical examination, a medical representative may decrease the dose or reject the preparation intake.


Blood pressureA patient should always inform his consulting physician about all other medicines he has been taking, including OTC (over-the-counter), recreational drugs, herbal remedies, and dietary supplements as they may interact with sildenafil.

Here are the drug classes which are strictly forbidden for co-administration with Viagra:

  1. Nitrate drugs, for example nitroglycerin (Nitrostat), isosorbide dinitrate (Dilatrate-SR) for angina or other heart problem cures. Recreational drugs (amyl nitrate or nitrite) also contain nitrates. Combined intake with sildenafil leads to critical blood pressure drops.
  2. Alpha-blockers. Combination of these drugs with sildenafil decreases blood pressure.
  3. Other preparations for ED (Cialis, Levitra, Stendra). Interactions lead to overdosing symptoms, multiple side effects, and priapism.

A few preparations that are forbidden for joint usage with Viagra are below:

  • Bosentan (Tracleer);
  • Cimetidine (Tagamed);
  • Imatinib (Gleevec);
  • Hypericum perforatum (St. John’s wort);
  • Nefazodone (Serzone);
  • macrolides: erythromycin (EryPed 200, EryPed 400), clarithromycin (Biaxin); azithromycin (Zithromax);
  • antifungal drugs: itraconazole (Sporanox), fluconazole (Diflucan);
  • heart and blood pressure preparations amiodarone (Pacerone, Cordarone, Nexterone), amlodipine (Norvasc);
  • drugs for hepatitis C cure: boceprevir (Victrelis);
  • protease inhibitors for HIV/AIDS treatment: atazanavir (Reyataz), ritonavir (Norvir), amprenavir (Agenerase);
  • medications for curing of seizure: fosphenytoin (Cerebyx), carbamazepine (Tegretol);
  • tuberculosis drugs: Isoniazid.

Is It Allowed to Take Sildenafil with Food?

Ideally, sildenafil should be taken on an empty stomach. By eating high fat meals, a man is more likely to gain weight which only worsens erectile problems. It is recommended to avoid fried and junk food. Best of all is eating low fat foods during the whole day when a man is planning to consume sildenafil.

According to the U.S. National Library of Medicine website PubMed Health, sildenafil may be taken regardless of meal time. A patient should avoid high fat meals because they slow down digestion processes and delay the start of Viagra work. They suggest taking sildenafil 1 hour before or during a meal compared to ordinary digestion of duration in 30 minutes-1 hour before planned sexual intercourse.

Grapefruit and grapefruit juice are worthy of special attention. This fruit impacts the work of all drugs, including Viagra. Preventing breakdown of the chemical agent in the organism, grapefruit provokes its greater uptake. It leads to high concentration of the drug in the blood and, as a result, various side effect manifestations. It is better to exclude this product out of daily ration while a patient is on Viagra treatment.

Alcohol Drinks

Alcohol drinksMany health experts warn men against taking alcohol during a Viagra treatment course. It threatens severe side effects manifestations. Nevertheless, many patients ignore this important rule. Some men even wrongly think that it helps to enhance sexual desire.

In fact, both sildenafil and alcohol have similar feature: they widen blood vessels. Their mix may lead to blood vessel dilation and may provoke such side symptoms as:

  • lightheadedness which increases risks of traumas;
  • fast and irregular heart rate;
  • blood pressure drops.

Among unwelcome interactions with Viagra, large amounts of alcohol worsen erectile problems, which is usually a result of much more serious health problems (like cardiovascular illnesses) which are not compatible with alcohol, either.

Alcohol affects the erection process. In addition to a hangover and a sore head, it complicates the natural erection process, reducing effectiveness of the drug and making sexual activity impossible.

If a patient’s health is good and stable, the appropriate dose of light alcohol drinks (wine or beer) is no more than 2 units. This fact should be discussed with a personal medical representative in private.

Intake with Other Drugs

Not all drugs should be rejected during a course of sildenafil. It can be taken with Rx and OTC drugs after a preliminary medical consultation. In most cases, a patient is prescribed a personal scheme of cure.

The table represents a few examples of co-administration of sildenafil with other drugs. Potential for serious interactions medications demand regular medical monitoring or alternative drug. Significant interactions require a doctor’s monitoring. Minor interactions are not significant.

Serious interactions Significant interactions Minor infractions
Drug Effect Drug Effect Drug Effect
Alfuzosin (Uroxatral) Hypotension Zafirlukast (Accolate) Sildenafil increases the effect of zafirlukast Carvedilol (Coreg CR) Low blood pressure; increased sildenafil effect
Boceprevir (Victrelis) Hypotension, syncope, eyesight problems, priapism Butabarbital (Busodium) Butabarbital decreases sildenafil effect Fluvoxamine (Luvox CR) Fluvoxamine increases sildenafil effect
Carbamazepine (Tegretol XR) Decreases sildenafil effect Verapamil (Verelan) Sildenafil increases the effect of verapamil Sapropterin (Kuvan) Low blood pressure
Doxazosin (Cardura) Doxazosin increases effects of sildenafil Crizotinib (Halkori) Crizotinib increases the levels of sildenafil Labetalol (Trandate) Sildenafil increases effects of labetalol
Ketoconazole (Nizoral) Ketoconazole increases the level of sildenafil Dabrafenib (Tafinlar) Dabrafenib decreases the level of sildenafil Labetalol iv (Normodyne IV) Labetalol iv increases effects of sildenafil


Erectile dysfunctionED is a widespread form of sexual dysfunction in males. PDE5 inhibitors are the first-line treatment for these cases. Multitudinous clinical tests and studies have constituted the reliability and effectiveness of these drugs in ED problems.

Sildenafil was the first approved drug for this purpose. Later, new agents with other pharmacokinetic profiles and new formulations were marked. Traditional «on-demand» consumption evolved to a daily one. The progression provides more adaptability in an ED cure for patients and medical staff.

PDE5 inhibitors showed excellent results in symptomatic treatment of BPH and hypertension. Thusly, the elaboration of this drug class is acclaimed and highly influential in medical experience.

The most popular and efficient medicines for ED cure:

  • sildenafil (Viagra);
  • tadalafil (Cialis);
  • vardenafil (Levitra);
  • udenafil (Zydena);
  • mirodenafil (Mvix S);
  • avanafil (Stendra).

As far as they all belong to one drug class, the mechanism of work is similar. The difference consists mainly in the regime of taking and the clinical effect, respectively. The table below represents the distinction between medicines that are purposed for daily usage and on an as-needed basis. Choosing the preparation for yourself, you should pay attention at these important factors.

Variable quality Daily usage drugs As-needed basis drugs
Time limit for sex Yes No
Periodicity of sex Any For high frequency
Peak plasma concentration of the active substance Sufficient May be not enough if a patient fails the regime of treatment
Risk of side effects Higher Lower
Costs for treatment Comparatively lower Higher
Advantages on lower urinary tract symptoms Discontinuously Invariably

Levitra Vs Sildenafil

Both Viagra and Levitra are effective medications for ED treatment. However, every patient should decide for himself which one he would like to use. The choice can be easily made on the basis of the most important factors which are represented in the table below. If the chosen preparation appeared ineffective or provided annoying adverse symptoms, a patient can easily switch it to another drug.

Criterion Levitra Viagra
Active substance Vardenafil Sildenafil
Brand owner Bayer Corp., distributed by GlaxoSmith Kline Pfizer
FDA approved 20th August, 2003 March 27, 1998
Generics Vardenafil hydrochloride Sildenafil citrate
Dosages 2.5 mg, 5 mg, 10 mg, 20 mg, 40 mg, 60 mg 20 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg, 200 mg
Starting dose 10 mg 50 mg
Sales claim Works faster, treats the cases where Viagra was helpless Exists in the market 5 years longer than Cialis and 7 years longer than Levitra
Non prescription No No
When to take 60 minutes hour before sex At least 30 minutes before sex
Working time Up to 8 hours 4-5 hours
Half-life 4-5 hours 4 hours
Medical purpose Treatment of ED problems
Drug glass PDE5 inhibitors
Drugs interaction Nitrates, alpha-blockers and more
Side effects Stuffy or runny nose, migraine, indigestion, vision changes, blushing, priapism
Consumption instructions Regardless of meal time
Allowed frequency of taking Once in 24-hours period
Storage 15-30°C

Is Cialis (Tadalafil) Better?

Cialis and Viagra are tailored for ED treatment. Although these medicines belong to one drug family, they have significant differences. Viagra acts quicker, a patient feels its effect within half an hour after the pill consumption. Cialis may take up to 2 hours. A patient should choose only one drug and should never take tadalafil and sildenafil together. Duplicate treatment may become a reason for priapism and other side effects.

Criterion Cialis Viagra
Active substance Tadalafil Sildenafil
Brand owner Developed by Ocos, marketed by Eli Lilly Pfizer
FDA approved November 21, 2003 March 27, 1998
Generics Tadalafil Sildenafil citrate
Dosages 2.5 mg, 5 mg, 10 mg, 20 mg, 40 mg, 60 mg 20 mg, 25 mg, 50 mg, 75 mg, 100 mg, 150 mg, 200 mg
Sales claim «Weekend pill» with action up to 36 hours The first ED pill in the pharmacy market
Non prescription No No
Working time Up to 36 hours 4-5 hours
Half-life 18 hours 4 hours
Allowed frequency of taking Once in 24-36 hours period Once in 24-hours period
Side effects Blushing, chest pain, stuffy nose, vertigo, hypotension Blushing, migraine, stomach upsets, blue vision
Drugs interaction Alpha-blockers, nitrates, hepatitis C, tuberculosis medications, and more Nitrates, alpha-blockers, and more
Medical purpose Treats ED and pulmonary heart disease
Drug glass PDE5 inhibitors
Consumption rules Regardless of meal time
Storage 15-30°C

Natural Sources of Sildenafil

Ginkgo bilobaDespite the advantages of sildenafil, its working time is limited. To prolong the result, a patient should take more and more drugs. Luckily, nature has provided alternatives used since ancient times before the invention of Viagra. Those who aspire to avoid ED in the future or sustain light forms of it should try using the following substitutes:

  1. Muira Puama. This pristine herb grows in the Brazilian Amazon rainforests and got the nickname «potency wood». All parts of the plant are aphrodisiacs, increase libido and improving ED symptoms without unwanted reactions. The herb was tested in 1994 by medical sexologist Dr. Jacques Waynberg. During 2 weeks, 262 men with ED symptoms received 1-1.5 g of the moire puma extract. 62% valued the therapy as functional and 52% as curative. Research notes that only alcohol infusion on the base of the plant provides results in curing ED. Due to the insolubility of the components, powdered drugs (capsules and tablets) are not efficient.
  2. Ginkgo Biloba. The National Chinese tree grows in Korean and Japanese forests. Local people eat the nuts for an aphrodisiac. Ginkgo Biloba’s leaves increase blood circulation. During clinical tests, it showed benefits in 78% of tested men with impotence and good blood supply to the genital area. The duration of the cure lasts up to 3 months. The remedy does not have side effects.
  3. Maca Root. A world-famous plant that grows in the high mountains of Colombia, Peru, Chile, and Bolivia. This effective energy enhancer was applied to sexual problems, prostate and cognitive diseases. It increases fertility and provides relieving effect on females in the menopausal period. Thought its results are not as fast as Viagra’s, the effect is long-term and lasts after treatment. Alcohol infusions show the best therapeutic results.

The plants which demand more scientific evidenc are yohimbe, horny goat weed, and red ginseng. Although, all natural remedies do not have immediate effect, this way of treatment is safer for general health. Before taking any natural aphrodisiacs, the preliminary consultation with a naturopath is highly recommended.

Some powerful foods act like Viagra and can boost the sex drive, too. The components in natural foods are absolutely safe and do not require dosages. For a stronger erection, it is healthy to eat:

  • watermelons;
  • eggs;
  • walnuts;
  • spinach;
  • bananas;
  • dark chocolate;
  • avocados;
  • pomegranate;
  • asparagus;
  • cardamon.

It should be noted that healthy components in food may help to prevent possible erectile problems but scarсely can cure the existing disease.

Sildenafil Reviews

Viagra is a world-famous drug. It has been widely used by men all over the world and most patients stay satisfied with the results. 73 y. o. patients feel like 23, and some of them noticed an absolute absence of side effects. The price stays a meaningful question, which actually can be successfully solved by generics.

Rating diagram of Viagra

Side effects remain questionable. The diagram below represents the most frequently discussed themes in the Internet about sildenafil, concomitant diseases, and side symptom estimation. The total rating of Viagra is 4.4 of 5 which means that people are satisfied with this drug.

Such adverse effects as nasal congestion, headache, and blood pressure drops are well-known and scientifically marked. Viagra does not cause skin cancer (melanoma), as was proved during a clinical trial. Patients should appeal for medical consultation regarding any health condition. It is very likely that your fears are groundless.

Effectiveness and Benefits

The effectiveness of sildenafil was proved during multiple scientific studies. The treatment was efficient even in severe ED cases. Despite a long existence in the pharmaceutical industry, this drug has not lost its popularity. Millions of patients are satisfied with the results and choose sildenafil for regular usage. Such popularity is absolutely deserved.

It showed amazing results not only in restoring sexual function, but in PAH, heart diseases, mountain sickness therapy, and Raynaud’s phenomenon. Its effect in females with sexual dysfunction and pregnant women shows that all sildenafil benefits are not discovered yet. Clinical tests go on, and maybe soon we will know about more advantages of this «magic blue pill».

Where and How to Buy Sildenafil Without Prescription?

Purchasing in online shopThe next question for patients who have chosen sildenafil for an ED cure is where to buy it. Viagra is sold in any local pharmacy. Be ready to provide a prescription to the pharmacy representative and pay extra money because the price for sildenafil is not covered by state insurance. The original Pfizer product is not a cheap drug.

The cheapest option is to order the medicine from Indian drug stores. Here come a few problems, too. A purchaser should be sure that he buys a product of high quality. The investigations might take some time, and the result may be unpredictable. There are possible problems at the custom services because FDA laws are very skeptical about all incoming drugs.

Our online pharmacy CialisBit offers the most convenient way of purchase. In our drug store, sildenafil is represented under different trade names. Also, you can find many other preparations for treatment and regular cure of erectile problems and premature ejaculation (Cialis, Stendra, and many more). In our pharmacy, you can buy any drug without prescription.

We sell only high quality generics at a fair price. All medicines come from our Indian laboratories and are sent through the US within 7-18 days. Quick shipment, payment, and big discounts (-35%) for Bitcoin payment are the benefits of online order in our chemists. Cure your delicate problems professionally at the most favorable prices.