Viagra (Sildenafil Citrate)
Viagra is a prescription medication containing sildenafil citrate, a PDE5 inhibitor used by adult men to support erections during sexual activity in cases of erectile dysfunction. Tablets come in 25mg, 50mg and 100mg.
- Active ingredients
- Sildenafil Citrate
- Manufacturer
- Pfizer
- Dosage forms
- tablet
- Available dosages
- 25mg, 50mg, 100mg
- Category
- Erectile Dysfunction (ED)
What is it?
Viagra is the original brand name for sildenafil citrate, an oral medication first approved in 1998 for the treatment of erectile dysfunction in adult men. It is manufactured by Pfizer and is one of the most widely studied phosphodiesterase type 5 inhibitors. The drug does not cause an erection on its own — sexual stimulation is required for it to work — and it is available only on prescription in most countries.
Active ingredients
Each tablet contains sildenafil citrate as the active ingredient, supplied in three commercial strengths: 25mg, 50mg and 100mg. Sildenafil citrate is a selective inhibitor of phosphodiesterase type 5, the enzyme responsible for breaking down cyclic guanosine monophosphate in the corpus cavernosum. By blocking this enzyme, the drug allows the natural chemical signals triggered by arousal to produce a firmer and more sustained erection.
Forms and dosages
Viagra is supplied as round, blue, film-coated tablets. Adult men typically begin with 50mg taken approximately one hour before planned sexual activity. Depending on tolerability and effect, the dose may be lowered to 25mg or increased to 100mg by a prescribing physician. The maximum recommended frequency is once per 24 hours. Tablets can be taken with or without food, although high-fat meals may delay onset of action.
Indications
The medication is indicated in adult men for the treatment of erectile dysfunction, defined as the inability to achieve or maintain a penile erection sufficient for sexual activity. It is not indicated for women, paediatric patients or men without a diagnosis of erectile dysfunction. According to the manufacturer's prescribing information, treatment should be considered only after a clinician has assessed underlying causes and cardiovascular fitness.
How it works
During sexual stimulation, nitric oxide is released in the corpus cavernosum and activates an enzyme that produces cyclic GMP. Cyclic GMP relaxes the smooth muscle in the penile arteries, allowing increased blood flow and an erection. Sildenafil citrate prevents PDE5 from degrading cyclic GMP, which prolongs its action. Onset is typically within 30 to 60 minutes, with effects lasting up to four hours according to clinical trials.
Frequently asked questions
How long does Viagra take to work? ▾
Most clinical trials report onset of action between 30 and 60 minutes after a dose is taken on an empty stomach. A meal high in fat can delay this onset. Sexual stimulation is needed before the medication produces an effect — the tablet alone does not cause an erection. The published prescribing information states that the effect can last up to four hours, although individual response varies.
What dose of Viagra should I start with? ▾
According to the manufacturer's prescribing information, most adult men begin treatment with the 50mg strength, taken approximately one hour before planned sexual activity. Depending on tolerability and effect, the prescribing physician may reduce the dose to 25mg or increase it to 100mg. The maximum dosing frequency is one tablet per 24 hours. Decisions about the starting dose should always be made by a clinician familiar with the patient's medical history.
Can Viagra be taken with food? ▾
Viagra can be taken with or without food, but published clinical data show that a high-fat meal can delay the medication's onset of action by approximately one hour and may slightly reduce its peak concentration. Light meals or empty stomach are usually preferred when a predictable onset is needed. Alcohol in moderate amounts is unlikely to alter the medication's pharmacokinetics, but heavy intake may impair erectile response on its own.
Is Viagra the same as generic sildenafil? ▾
Viagra is the original brand of sildenafil citrate manufactured by Pfizer. Generic sildenafil contains the same active ingredient at the same strengths and is held to the same regulatory bioequivalence standards in markets where it is approved. Differences may include excipients, tablet shape, colour and price. According to regulators, an authorised generic should produce comparable clinical effects, although individual response can vary.
Does Viagra interact with other medications? ▾
Yes — sildenafil citrate has clinically important interactions, most notably with nitrates used for chest pain, where the combination can cause a severe drop in blood pressure and is contraindicated. Other interactions include alpha-blockers, certain antifungal and HIV medications and grapefruit juice in large quantities. According to the prescribing information, anyone taking other medicines should disclose them to a clinician before starting Viagra.
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The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.