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Generic Name:

sildenafil, Oral tablet

Viagra

Viagra

Generic Name: sildenafil, Oral tablet

All Brands

  • Viagra
SECTION 1 of 4

Highlights for Viagra

Oral tablet
1

Viagra is used to treat erectile dysfunction (ED). ED is also called impotence. This drug helps men with ED get and keep an erection.

2

Viagra comes in the form of a tablet you take by mouth. The usual dose is 50 mg, as needed, about 1 hour before sexual activity. Viagra should not be taken more than once per day.

3

• Viagra is available as a brand-name drug. It’s also available as a generic drug.

4

The more common side effects of Viagra can include headache, flushing (sudden reddening of the face), upset stomach, or vision problems.

5

In some cases, Viagra can cause serious side effects. These can include sudden vision loss, hearing loss, or an erection lasting more than 4 hours.

IMPORTANT INFORMATION

Priapism (an erection that will not go away)

If you have an erection that lasts more than 4 hours, call 9-1-1 or go to the nearest emergency room. If it’s not treated right away, this condition can cause permanent damage to your penis.

Sudden vision loss in one or both eyes

Sudden vision loss in one or both eyes can be a sign of a serious eye problem. If this occurs, stop taking Viagra and call your doctor right away.

Sudden hearing decrease or hearing loss

Some people may have tinnitus (ringing in their ears) or dizziness. If you have these symptoms, stop taking Viagra and call your doctor right away.

Sexually transmitted diseases

The use of Viagra does not offer protection against sexually transmitted diseases or HIV (human immunodeficiency virus). Use a condom during sex, or talk with your doctor about other ways to protect yourself from these diseases.

What is Viagra?

Viagra is a prescription drug. It comes in the form of a tablet you take by mouth.

Viagra is available as a brand-name drug. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name version.

Why it's used

Viagra is used to treat erectile dysfunction (ED). ED is also called impotence. With this condition, men cannot get or keep an erection. Viagra helps men with ED get and keep an erection. 

Viagra only works when you are sexually excited. You won’t get an erection just by taking this drug.

How it works

Viagra belongs to a class of drugs called phosphodiesterase-5 (PDE5) inhibitors. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions. 

Viagra works by increasing blood flow to the penis. This allows you to get and keep an erection.

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SECTION 2 of 4

Viagra Side Effects

Oral tablet

More Common Side Effects

Click here to learn more about how this drug affects the body.

The more common side effects of Viagra can include:

  • headache

  • flushing (sudden reddening of the face)

  • upset stomach

  • abnormal vision, such as:

    • changes in color vision (including seeing a blue tinge)
    • blurred vision
  • stuffy or runny nose

  • back pain

  • muscle pain

  • nausea

  • dizziness

  • rash

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Priapism (an erection that won’t go away). Symptoms can include:

    • an erection that lasts more than 4 hours
  • Vision problems. Symptoms can include:

    • sudden vision loss in one or both eyes
  • Hearing problems. Symptoms can include:

    • sudden hearing decrease or hearing loss
    • tinnitus (ringing in the ears)
    • dizziness
Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

Viagra does not cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 4

Viagra May Interact with Other Medications

Oral tablet

Viagra can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Food interactions

If you take Viagra after a high-fat meal, it may take up to an hour longer to start working.

Alcohol interaction

Viagra can cause low blood pressure. The use of drinks that contain alcohol raises your risk of this side effect. If you drink alcohol, talk to your doctor. Your blood pressure may need to be monitored.

Medications that might interact with this drug

Drugs you should not use with Viagra

Do not take these drugs with Viagra. Doing so can cause dangerous effects in the body. Examples of these drugs include:

  • Nitrates, such as isosorbide dinitrate, isosorbide mononitrate, or nitroglycerin.
    • Using these drugs with Viagra can cause your blood pressure to drop suddenly to an unsafe level.
  • Guanylate cyclase stimulators, such as riociguat.
    • Using these drugs with Viagra can cause your blood pressure to drop suddenly to an unsafe level.

Interactions that increase your risk of side effects

Side effects from Viagra: Taking Viagra with certain medications raises your risk of side effects from Viagra. This is because the amount of Viagra in your body may be increased. Examples of these drugs include: 

  • HIV protease inhibitors, such as ritonavir, indinavir, saquinavir, or atazanavir.
    • Increased side effects can include low blood pressure, dizziness, vision problems, or long-lasting erection. Your doctor may decrease your dosage of Viagra.
  • Certain antibiotics, such as clarithromycin, telithromycin, or erythromycin.
    • Increased side effects can include low blood pressure, dizziness, vision problems, or long-lasting erection. Your doctor may decrease your dosage of Viagra.
  • Certain antifungals, such as ketoconazole or itraconazole.
    • Increased side effects can include low blood pressure, dizziness, vision problems, or long-lasting erection. Your doctor may decrease your dosage of Viagra.

Side effects from other drugs: Taking Viagra with certain medications raises your risk of side effects from these drugs. Examples of these drugs include:

  • Alpha-blockers, such as terazosin, tamsulosin, doxazosin, alfuzosin, or silodosin.
    • Increased side effects can include a drop in blood pressure, or fainting. 
  • Blood pressure drugs, such as amlodipine.
    • Increased side effects can include a decrease in blood pressure to an unsafe level.
  • Other drugs or treatments for ED, such as avanafil or tadalafil.
    • Increased side effects can include low blood pressure, fainting, vision problems, or long-lasting erection.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Viagra warnings
heart problems
People with heart problems

Viagra can lower your blood pressure. If you’ve had certain heart problems during the last 6 months, talk with your doctor about whether this drug is safe for you. These problems include a heart attack, stroke, or life-threatening heart rhythm problem. Also talk with your doctor if you have a low or high resting blood pressure, or a history of heart failure or coronary artery disease.

eye problems
People with eye problems

Viagra may cause sudden loss of vision in one or both eyes. This may be a sign of a condition called non-arteritic anterior ischemic optic neuropathy (NAION). If you’ve already had NAION, or if you have a condition called crowded optic disc, your risk of NAION and vision changes is increased. If you have a sudden loss of vision, stop taking this drug and call your doctor right away.

kidney problems
People with kidney problems

If you have kidney problems or a history of kidney disease, you may not be able to clear Viagra from your body well. This may increase the levels of this drug in your body and cause more side effects. Your doctor will likely start you on a lower dose of this medication.

liver problems
People with liver problems

If you have liver problems or a history of liver disease, your body may not be able to process Viagra well. This may increase the levels of this drug in your body and cause more side effects. Your doctor will likely start you on a lower dose of this medication.

seniors
For seniors

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

children
For children

This medication has not been studied in children. It should not be used in people younger than 18 years.

call the doctor
When to call the doctor

Call your doctor right away if you have symptoms such as chest pain, dizziness, or nausea during sex. Sexual activity can put an extra strain on your heart, especially if your heart is already weak from a heart attack or heart disease. Before taking Viagra, ask your doctor if your heart is healthy enough to handle the extra strain of having sex.

allergies
Allergies

Viagra can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your throat or tongue 

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

SECTION 4 of 4

How to Take Viagra (Dosage)

Oral tablet

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Erectile dysfunction (ED)

Brand: Viagra

Form: Oral tablet
Strengths: 25 mg, 50 mg, 100 mg

Generic: Sildenafil

Form: Oral tablet
Strengths: 25 mg, 50 mg, 100 mg
Adult dosage (ages 18–64 years)
  • Typical starting dosage: 50 mg as needed, about 1 hour before sexual activity. Viagra may be taken anywhere from 30 minutes to 4 hours before sexual activity. Don’t take it more than once per day.
  • Maximum dosage: Your doctor may increase your dose to a maximum of 100 mg. This depends on how the drug is working for you and if you’re having any side effects.
Child dosage (ages 0–17 years)

This medication has not been studied in children. It should not be used in people younger than 18 years.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dose of 25 mg. This can help keep levels of this drug from building up too much in your body.

Special considerations

Kidney disease: If you have severe kidney disease, your doctor may start you on a lowered dose of 25 mg. This can help keep levels of this drug from building up too much in your body.

Liver disease: Your doctor may start you on a lowered dose of 25 mg. This can help keep levels of this drug from building up too much in your body.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

Viagra comes with serious risks if you don’t take it as prescribed.

If you take too much

You could have dangerous levels of the drug in your body. Symptoms of an overdose of Viagra can include:

  • an erection that lasts longer than 4 hours
  • low blood pressure
  • fainting
  • dizziness
  • vision changes, such as blurred vision or changes in color vision (including a blue tinge)
  • pain in the abdomen (stomach area)
  • muscle pain

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

How to tell if the drug is working

You should be able to get and keep an erection when sexually excited. 

Viagra is used for short-term treatment.

You can take Viagra with or without food

If you take this drug after a high-fat meal, it may take up to an hour longer to start working.

Take Viagra about 1 hour before sexual activity

If needed, you can take this drug from 30 minutes to 4 hours before sexual activity. Don’t take it more than once per day.

Store this drug carefully

  • Store this drug at room temperature between 59°F and 86°F (15°C and 30°C).
  • Keep this medication away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

You and your doctor should monitor certain health issues. This can help make sure you stay safe while you take Viagra. These issues include:

  • Kidney function. Blood tests can check how well your kidneys are working. If your kidneys aren’t working well, your doctor may decide to lower your dose of this drug.
  • Liver function. Blood tests can check how well your liver is working. If your liver isn’t working well, your doctor may decide to lower your dose of this drug.
  • Blood pressure. Your doctor may monitor your blood pressure and pulse often if you’re taking other medications that may lower blood pressure.

Hidden costs

You may need to have blood tests during your treatment with Viagra. The cost of these tests will depend on your insurance coverage.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor may need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.


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Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on April 16, 2016

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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