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Medication

Sildenafil

Written by the Verra clinical team · Medical review pending · Last updated Oct 4, 2026

Quick answer

Sildenafil is a PDE5 inhibitor that improves blood flow to the penis to help with erections during sexual arousal. It is the active ingredient in Viagra. It is taken as needed about an hour before sex and must not be combined with nitrates.

Key takeaways

  • Works for about 4 to 6 hours.
  • A heavy meal can delay its effect.
  • Never take with nitrates or riociguat.

What it is

An oral medication for erectile dysfunction.

How it works

It relaxes blood vessels so more blood can flow in with arousal.

Forms and doses we offer

Tablets and a combination chew, in doses your provider selects.

Common side effects

Headache, flushing, nasal congestion, indigestion and temporary vision tint.

Who should not take it

Anyone taking nitrates, with recent heart attack or stroke, very low blood pressure or certain eye conditions.

Interactions to discuss

Nitrates, alpha-blockers, some HIV and antifungal medicines, and alcohol.

Verra treatments containing sildenafil

A licensed provider decides whether a treatment is appropriate after your visit.

Questions

How does sildenafil help with erectile dysfunction?

Sildenafil helps increase blood flow to the penis during sexual arousal. This can help some people get and keep an erection. Results vary. It belongs to a drug group called PDE5 inhibitors. It does not increase sexual desire or cause an erection without sexual stimulation.

When should I take sildenafil before sex?

Sildenafil is usually taken as needed about one hour before sex. For standard oral tablets, the usual timing range is 30 minutes to four hours before sex. Follow your prescription instructions. Results vary. Sexual stimulation is needed, and you should not take extra doses to make it work faster.

What dose of sildenafil should I take for ED?

Take only the sildenafil dose prescribed for you. Your physician chooses it based on your health, other medicines, and side effects. Do not increase the dose yourself or take it more often than directed. For ED, use is generally limited to one dose in 24 hours, sometimes less often.

Why must sildenafil never be combined with nitrates?

Sildenafil and nitrates can cause a dangerous drop in blood pressure when taken together. Do not use sildenafil with nitroglycerin, isosorbide medicines, or recreational nitrites called poppers. If chest pain occurs after sildenafil, call 911, do not take a nitrate, and tell emergency staff when you took sildenafil.

What side effects can sildenafil cause?

Sildenafil can cause headache, flushing, indigestion, a stuffy nose, dizziness, or changes in color vision. Contact your prescriber if side effects bother you. Get emergency care for an erection lasting more than four hours. Sudden loss of vision or hearing also needs immediate medical attention.

Who needs extra medical review before taking sildenafil?

Sildenafil is not appropriate for everyone. A licensed physician in your state must review your health and medicines. Tell them about heart disease, low blood pressure, recent stroke or heart attack, kidney or liver problems, eye conditions, or past prolonged erections. Nitrates and riociguat must not be combined with sildenafil.

Which medicines and supplements can interact with sildenafil?

Sildenafil can interact with blood pressure medicines, alpha blockers, certain antibiotics, antifungals, HIV medicines, and other ED treatments. Nitrates and riociguat must not be used with it. Share every prescription, over-the-counter drug, supplement, and recreational substance with your physician and pharmacist before taking sildenafil or starting something new.

Can I take sildenafil with food, alcohol, or grapefruit?

Standard oral sildenafil tablets can be taken with or without food, but a high-fat meal may delay the effect. Results vary. Alcohol can add to dizziness and make erections harder to achieve. Ask your pharmacist about grapefruit, which may affect sildenafil levels, and follow your specific product's instructions.

What should I do if sildenafil does not work or I want to stop?

If sildenafil does not help, contact your prescriber instead of increasing the dose or adding another ED medicine. Results vary. They can review timing, food, sexual stimulation, and other health concerns. As-needed sildenafil for ED generally does not need tapering, but discuss ongoing symptoms or a treatment switch with your physician.

How can I request sildenafil through Verra Health, and what does the visit cost?

You can request a sildenafil review through Verra Health with an online or video visit. A licensed physician in your state decides whether to prescribe. The online visit fee is $99; the video visit fee is $149. Medication is charged only after approval. Current medication pricing appears on the treatment page.

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Sources

This page is general information, not medical advice. Results vary. Compounded medications are not FDA-approved. Our editorial policy

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