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Last updated December 26, 2019. 3 minute read

Viagra (sildenafil) side effects and safety information

More common side effects of Viagra include dizziness, headache, flushing, upset stomach or indigestion, increased sensitivity to light, blurred vision, “blue-tinted” vision, a stuffy or runny nose, insomnia, rash, and muscle pain.

Self Written by Michael Martin
Reviewed by Dr. Mike Bohl, MD, MPH

Viagra (sildenafil) is an oral medication that treats erectile dysfunction (ED).

Viagra (sildenafil), Cialis (tadalafil), Levitra (vardenafil), and Stendra (avanafil) are all part of a family of drugs called PDE-5 inhibitors. PDE-5 is a natural chemical that encourages blood to flow out of the penis through a series of reactions. Viagra works by blocking PDE-5. This increases levels of a substance known as cGMP, which relaxes smooth muscle and encourages blood vessels to widen. That makes blood flow more freely, including to the penis.

You need to feel sexually aroused for Viagra to work, and it usually starts working about 30 to 60 minutes after taking it.

Viagra requires a prescription; it is not available over-the-counter.

Vitals

  • Viagra (sildenafil) is a medication used to treat erectile dysfunction (ED).
  • Side effects are possible with Viagra, as with any drug.
  • In clinical trials, about 2% of Viagra users experienced side effects.
  • Viagra can cause drug interactions, and people who are taking certain medications or have certain health conditions shouldn’t use Viagra.

What is the typical dose of Viagra?

According to the FDA-approved Prescribing Information, the recommended dose of Viagra for most people is 50 mg taken as needed (although some do better with 25 mg and some do better with 100 mg). Your doctor will decide what dosage is right for you based on your medical history, symptoms, and preferences. If you experience unwanted side effects on the dose your doctor prescribes, talk to your doctor before changing your dose.

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Potential side effects of Viagra

More common side effects of Viagra include dizziness, headache, flushing, upset stomach or indigestion, increased sensitivity to light, blurred vision, “blue-tinted” vision, a stuffy or runny nose, insomnia, rash, and muscle pain.

Less common side effects of Viagra include priapism (a prolonged erection that won’t go away), heart attack-like symptoms, eye problems such as sudden vision loss, ringing in ears or hearing loss, seizures, or swelling in the extremities.

Potential considerations when taking Viagra

Viagra might cause adverse reactions when taken with other medications (including Revatio), similar PDE-5 inhibitor drugs (such as Cialis, Levitra, or Stendra), antibiotics, antifungals, antiretrovirals, nitrates (a medication for high blood pressure or heart disease), or treatments for BPH.

Viagra can cause low blood pressure, usually within one to two hours after taking it. If you already have low blood pressure, talk with your healthcare provider about whether you should take Viagra.

Do NOT take Viagra if you:

  • Take nitrates
  • Take riociguat for pulmonary arterial hypertension
  • Are allergic to sildenafil or any of the inactive ingredients in Viagra
  • Are not healthy enough for sexual activity

Taking Viagra along with amyl nitrate (poppers) can lead to a dangerous, even fatal, drop in blood pressure.

How common are Viagra side effects?

In clinical trials, the most common side effects occurred in more than 2% of participants, but whether an individual will experience side effects depends on a number of factors personal to them. Before taking Viagra, or any ED medication, talk to your doctor about possible side effects and whether you’re healthy enough for sex.

What to do if you experience side effects

If you experience side effects while taking Viagra, talk to your doctor right away. You should stop using Viagra and seek immediate medical help if you experience any of the following serious side effects:

  • Sudden vision loss in one or both eyes
  • Sudden decrease or loss in hearing
  • Chest pain, dizziness, or nausea during sex
  • An erection lasting longer than four hours (priapism)

To learn more about the side effects of Viagra, see Important Safety Information, or read the full Prescribing Information and Patient Information, which contain information about Viagra that is approved by the FDA.