Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is approved for this use in males ages 18 years and older.
Viagra contains the drug sildenafil. Viagra works by increasing blood flow to your penis, which helps you have and keep an erection. But this drug only works if you’re sexually aroused.

• Brand Name(s): Viagra and Revatio
• Generic Name: Sildenafil (oral)
• Drug Class: Treats Erectile Dysfunction

Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, sildenafil works by increasing blood flow to the penis to help a man get and keep an erection.

This drug does not protect against sexually transmitted diseases (such as HIV, hepatitis B, gonorrhea, syphilis). Practice "safe sex" such as using latex condoms. Consult your doctor or pharmacist for more details.

IMPORTANT THINGS YOU SHOULD KNOW WHEN STARTING VIAGRA

• VIAGRA can cause your blood pressure to drop suddenly to an unsafe level if taken with certain other medicines. Do not take VIAGRA if you take any other medicines called "nitrates." Nitrates are used to treat chest pain (angina). A sudden drop in blood pressure can cause you to feel dizzy, faint, or have a heart attack or stroke.
• Do not take VIAGRA if you take medicines called guanylate cyclase stimulators which include:
  –Riociguat (Adempas®) a medicine that treats pulmonary arterial hypertension and chronic-thromboembolic pulmonary hypertension.
• Tell all your healthcare providers that you take VIAGRA. If you need emergency medical care for a heart problem, it will be important for your healthcare provider to know when you last took VIAGRA.
• Stop sexual activity and get medical help right away if you get 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. Ask your doctor if your heart is healthy enough to handle the extra strain of having sex.
• VIAGRA does not protect you or your partner from getting sexually transmitted diseases, including HIV—the virus that causes AIDS.

How to use Viagra

Read the Patient Information Leaflet provided by your pharmacist before you start taking sildenafil and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

To treat erectile dysfunction-ED, take this drug by mouth as directed by your doctor, usually as needed. Take sildenafil at least 30 minutes, but no more than 4 hours, before sexual activity (1 hour before is the most effective). Do not take more than once daily.

A high-fat meal may delay how quickly the drug begins to work.

The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Viagra dosage

The Viagra dosage your doctor prescribes will depend on several factors. These include:

• your age
• whether you have liver or kidney problems
• other medical conditions you may have
• other medications you may be taking

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Viagra comes as tablets that are taken by mouth. It’s available in three strengths: 25 mg, 50 mg, and 100 mg. Dosage for ED

The typical dose of Viagra for erectile dysfunction (ED) is 50 mg. You can take this dose 30 minutes to 4 hours before you plan to have sexual activity. But for most people, it’s recommended that you take your dose about an hour before having sex. Don’t take Viagra more than once a day.

Your doctor may prescribe a different dosage of Viagra for you depending on several factors. These factors may include whether you have liver or kidney problems, or if you’re taking certain other medications. If any of these factors apply to you, your starting dose might be 25 mg, which is lower than the typical recommended dose.
If you have questions about the Viagra dosage that’s right for you, talk with your doctor.

And keep in mind that if Viagra isn’t working for you, your doctor may increase your dose of the drug. But the maximum dose of Viagra is 100 mg.

Dosage questions

Below, we answer some common questions related to Viagra’s dosage.

Is Viagra’s dosage based on age or weight?

Your dosage of Viagra won’t be based on your weight, but it may be based on your age.

For example, people ages 65 years and older tend to get higher levels of Viagra in their blood after taking a dose. So, if you’re over 65 years of age, your doctor will usually recommend a starting dose of Viagra for you that’s lower than the typical starting dose. For example, they may recommend that you take 25 mg of the drug rather than 50 mg.

Can I take Viagra just for fun, even if I don’t have ED? If so, how much is safe to take?

No, you shouldn’t take Viagra if you don’t have ED. Viagra is a prescription medication that can have serious side effects. And it’s approved only to treat ED, not to be used recreationally.
You should only take Viagra if it’s been prescribed to you by a doctor who knows your medical history.

Will I need to use this drug long term?

Maybe. If you and your doctor determine that Viagra is safe and effective for you, you can likely take it for as long as you continue to need it.