Viagra (sildenafil)

Viagra is a brand-name oral tablet prescribed for erectile dysfunction (ED). Viagra contains the active ingredient sildenafil.

Drug details

You’ll find key information about Viagra below.

• Drug class:phosphodiesterase type 5 (PDE5) inhibitor
• Drug form: oral tablet
• Generic available? yes
• Prescription required? yes
• Controlled substance? no
• Year of FDA approval: 1998

Does Viagra work to treat ED?

Yes, it does. In several clinical studies, Viagra was effective in treating erectile dysfunction (ED). In these studies, males who used the drug had an improved ability to have and keep erections during sexual activity. To learn more about Viagra’s effectiveness, see the “Viagra uses” section below.

Note: Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Viagra typically starts to work between 30 and 60 minutes after you take a dose of the drug. But Viagra itself doesn’t give you an erection. You’ll need to be sexually aroused in order for the drug to work.

Viagra keeps working in your body for up to 5 hours. This means that if you’re aroused, you should still be able to get an erection up to 4 hours after taking a dose of Viagra.

Even though Viagra keeps working in your body for several hours, your erection shouldn’t last this long. In fact, in rare cases, Viagra can cause priapism (a long-lasting and sometimes painful erection).

Priapism is a medical emergency that needs to be treated right away. If it’s not treated, the condition can damage the tissues in your penis and cause irreversible erectile dysfunction.

If you have an erection that lasts longer than 4 hours, go to the nearest emergency room or call 911.

What can I do to make Viagra work faster?

Viagra may work faster if you take it on an empty stomach. If Viagra is taken with food, especially with a high fat meal, it will take longer to start working. And in this case, it could even be less effective for you.

Viagra is approved to treat erectile dysfunction (ED) in males. With ED, you have trouble getting and keeping an erection that’s firm enough to allow you to have sex.

What causes an erection?

When you’re sexually aroused, your brain sends messages to your penis. These messages cause certain chemicals to be released in your penis.

One of these chemicals, called cyclic GMP, relaxes and widens certain blood vessels in your penis. Cyclic GMP also relaxes the muscles around the erectile tissue in your penis that’s called the corpus cavernosum. These actions allow blood to flow into the corpus cavernosum, which causes your penis to get hard and become erect.

What happens with ED?

ED can occur if you have certain problems that affect your body’s ability to have an erection. The condition can result from problems with messages being sent from your brain. ED can also result from problems with blood flow into your penis.

What does Viagra do for ED?

Viagra works to treat ED by helping you get and maintain an erection. The drug does this by improving blood flow into your penis when you’re sexually aroused.

Viagra is a type of drug called a phosphodiesterase type 5 (PDE5) inhibitor. It works by inhibiting (blocking) the action of an enzyme called PDE5. (An enzyme is a protein that helps chemical reactions to happen inside your body.)

Usually, an erection goes away when PDE5 breaks down the cyclic GMP in your penis. But Viagra blocks the action of PDE5, so it allows cyclic GMP to keep working for a longer period of time than usual. This action improves blood flow to your penis and helps you get and keep an erection.

Does Viagra increase a man’s sex drive?

No, Viagra doesn’t directly increase your sex drive. And it doesn’t make you sexually aroused. However, some people find that if Viagra works to treat their erectile problem, it also increases their sexual confidence. And this may lead to an increased sex drive.

How can I tell if Viagra’s not working?

Viagra may not work for everyone, and it may not work every time you take it.

If you’re sexually aroused, Viagra should work to help you get or keep an erection within 30 minutes to 2 hours. But if you don’t get an erection within 4 hours after taking a dose, Viagra didn’t work for you this time.

If the drug doesn’t work for you, you shouldn’t take another dose until at least 24 hours later. And talk with your doctor if you feel Viagra isn’t helping to treat your ED. They may recommend that you try a different medication for your ED.

How can I get Viagra to work?

It’s important to remember that Viagra only works if you’re already sexually aroused. Arousal may involve having sexual thoughts, looking at sexual images, masturbating, or engaging in foreplay.

But if you feel anxious, nervous, depressed, or stressed, your body may not respond well to sexual stimulation. If this is the case, try to relax, make yourself comfortable, and take your time. In addition, if you drink alcohol, it’s best to avoid drinking a lot of it. This is because consuming large amounts of alcohol can make it more difficult to get an erection.

If you’re having trouble getting an erection, even while using Viagra, talk with your doctor.

Is Viagra a blood thinner?

No, Viagra isn’t a blood thinner. Instead, it belongs to a group of drugs called phosphodiesterase type 5 (PDE5) inhibitors. Viagra works by blocking the action of a certain enzyme in your body.

Since Viagra has been released onto the market, there have been a few reports of bleeding in people who have taken the drug. However, there’s no evidence that Viagra caused these bleeding problems.

It’s not known if Viagra is safe for use in people with a bleeding problem. If you have any bleeding problems, talk with your doctor about whether Viagra is safe for you.

After taking a dose of Viagra, the drug’s level in your body will gradually decrease over a period of a few hours. You’ll have low levels of the drug in your body after about 4 hours. (And at this point, the drug won’t be working any longer.) But it can actually take about 24 hours for Viagra to be completely removed from your body.

If you have other questions about how long Viagra works, talk with your doctor.

Viagra can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Viagra. These lists don’t include all possible side effects.

For more information on the possible side effects of Viagra, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to report to the FDA a side effect you’ve had with Viagra, you can do so through MedWatch.

Mild side effects

Mild side effects of Viagra can include:*

• headache
• flushing
• indigestion
• mild and temporary vision changes, such as a blue tinge in your vision, blurred vision, and sensitivity to light
• nasal congestion (stuffy nose)
• back pain
• muscle pain
• nausea
• dizziness
• rash

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Viagra. To learn about other mild side effects, talk with your doctor or pharmacist, or view the drug’s prescribing information.

Serious side effects

Serious side effects from Viagra aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

• Non-arteritic anterior ischemic optic neuropathy (NAION), which is an eye condition that causes damage to your optic nerve. This is a medical emergency that should be treated right away. Symptoms can include:
  • sudden decrease in vision in one or both of your eyes
  • sudden loss of vision in one or both of your eyes
  • tinnitus (ringing or buzzing in your ears)
  • dizziness
  • an erection that won’t go away, and may not be fully firm
  • pain in the penis

  Other serious side effects, which are explained in more detail below in “Side effect details,” include:

  • allergic reaction
  • low blood pressure, if Viagra is taken with certain other medications
  • cardiovascular problems, such as heart attack, irregular heartbeat, or stroke, all of which occur mainly in people with heart disease

  Side effect details

  You may wonder how often certain side effects occur with this drug. Here’s some detail on several of the side effects this drug may cause.

  Note: You can also refer to this in-depth article for details about Viagra’s side effects.

  Allergic reaction

  As with most drugs, some people can have an allergic reaction after taking Viagra.

  Symptoms of a mild allergic reaction can include:

  A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

  Call your doctor right away if you have a severe allergic reaction to Viagra. But call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

  Low blood pressure

  Viagra can temporarily lower your blood pressure after you take the drug. This occurred in clinical trials but was not significant enough to cause problems for most people.

  But keep in mind that a sudden drop in your blood pressure could be dangerous if you have certain heart conditions. Sudden low blood pressure may also be dangerous if you’re taking certain other medications.

  For example, you should not take Viagra if you take nitrate medications to treat chest pain. You should also avoid taking Viagra if you take a drug called riociguat (Adempas). Taking Viagra with these medications can cause a dangerous drop in your blood pressure that leads to heart attack or stroke.

  If you have low blood pressure, taking Viagra could make you feel dizzy or lightheaded, or cause you to faint. You’re also more likely to have these problems if you take Viagra with certain drugs used to treat high blood pressure or enlarged prostate. If you feel dizzy or faint after taking Viagra, lie down until this feeling passes.

  If you have a heart problem or low blood pressure, talk with your doctor about whether Viagra is safe for you.

  For more information about taking Viagra with other medications, see the “Viagra interactions” section below. And for more information about taking Viagra if you have heart or blood pressure problems, see the “Viagra precautions” section below.

  Heart attack, irregular heartbeat, and stroke

  On rare occasions, some people taking Viagra have had a heart attack, stroke, or an irregular heartbeat. These conditions mainly occurred in people who already had a heart problem. But sometimes these conditions occurred in people who didn’t have a heart problem. It’s not known for sure if Viagra caused the side effects.

  If you have chest pain after taking Viagra, you should stop sexual activity right away. But call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

  And if you have a heart problem, talk with your doctor before starting Viagra. They can discuss with you whether it’s safe for you to use this drug. For more information about taking Viagra if you have heart problems, see the “Viagra precautions” section below.

  Headaches

  Headaches are a common side effect of Viagra. Headaches, as well as flushing and dizziness, occur because Viagra widens certain blood vessels in your body. (The drug doesn’t just affect the blood vessels in your penis.)

  If you have a headache after taking Viagra, it should go away fairly quickly. But if it’s bothersome, you can take a pain reliever containing acetaminophen or ibuprofen. Ask your doctor or pharmacist to recommend a medication that’s safe for you to use.

  If you have a severe headache or a headache that won’t go away, call your doctor. They’ll help determine the best treatment for your headache.

  How to relieve Viagra side effects

  Most of the mild side effects of Viagra either tend to go away within a few hours of taking your dose or can be easily relieved.

  For example, headaches, flushing, and dizziness can often be eased by lying down and resting. Avoiding alcohol will also help reduce these side effects. Headaches and sensitivity to light can also be improved by turning off any bright lights around you. If you have bothersome headaches with Viagra, ask your doctor or pharmacist to recommend a pain reliever that’s safe for you to use.

  If you get indigestion after taking Viagra, try taking your dose of Viagra with a snack or light meal. Just be aware that if you do this, Viagra may take slightly longer to start working for you. (This is especially true if you eat a high fat meal with your dose.) If your indigestion is bothersome, ask your doctor or pharmacist to recommend medication to help reduce your discomfort.

  Also keep in mind that certain side effects occur more often with higher doses of Viagra. These side effects include headaches, flushing, indigestion, nasal congestion, and changes in your vision. So if these side effects are a problem for you, talk with your doctor about taking a lower dosage of Viagra.

  When to call your doctor

  Some of Viagra’s rare side effects need immediate medical attention. For example, you should call your doctor or go to the nearest emergency room right away if you have:

  • an erection that doesn’t go away and lasts for more than 4 hours
  • chest pain, dizziness, or nausea while you’re having sex, and these symptoms don’t go away when you stop having sex and begin to rest
  • sudden loss of vision in one or both of your eyes
  • sudden decrease or loss of hearing