If you have erectile dysfunction (ED), your doctor might suggest Viagra (sildenafil) as a treatment option for you. As a result, you could be looking for more information about the drug, such as details about dosage.

Viagra is a prescription medication that’s used to treat ED in adult males.* A person who has this condition can’t get or keep an erection.

This medication comes as a tablet that you’ll take by mouth.

Viagra belongs to a group of drugs called phosphodiesterase 5 (PDE5) inhibitors. It treats ED by relaxing your blood vessels and increasing blood flow to your penis.

This article describes the dosages of Viagra, including its form, strengths, and how to take it. To learn more about Viagra, see this in-depth article.

Note: This article covers Viagra’s typical dosages, which are provided by the drug’s manufacturer. But when using Viagra, always take the dosage that your doctor prescribes.

* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

This section covers common questions about the dosage of Viagra.

What is Viagra’s form?

You may have heard Viagra described as the “little blue pill.” Viagra comes as a tablet that you swallow. It’s a blue tablet that has a rounded diamond shape.

What strengths does Viagra come in?

Viagra is available in three strengths: 25 milligrams (mg), 50 mg, and 100 mg.

What are the typical dosages of Viagra?

Typically, your doctor will start you on the recommended dosage. Then they’ll adjust your dosage over time to reach the right amount for you. Your doctor will ultimately prescribe the smallest dosage that provides the desired effect.

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

Dosage for erectile dysfunction

The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before sexual activity. And you shouldn’t take more than one dose per day.

After you try the 50-mg dose, you can let your doctor know how your body responded. This includes whether your erectile function improved or if you had any side effects.

Depending on how Viagra worked, your doctor may suggest decreasing your dose to 25 mg or increasing it to 100 mg. Or they may have you continue taking the 50-mg dose.

You’ll continue to take Viagra only as needed. The maximum dosage is once per day.

That said, the drug isn’t meant for daily dosing. If you’re interested in a once-daily treatment for ED, such as tadalafil (Cialis), talk with your doctor.

Maximum Viagra dosage

For most people, the maximum recommended dosage of Viagra is 100 mg once per day.

This dosage may be too high for people who have certain medical conditions or take certain medications. So it’s important not to take more Viagra than your doctor prescribes for you.

If your current dosage isn’t working well for your ED, talk with your doctor about increasing your dosage.

Is Viagra used long term?

Yes, Viagra is typically used as needed for ED. If you and your doctor determine that Viagra is safe and effective for you, you’ll likely use it as long as you have ED.

Dosage adjustments

A lower dosage of Viagra is safer for some people. This is typically due to certain factors, such as having specific medical conditions. These factors include:

  • being 65 years or older
  • having kidney or liver problems
  • taking a certain type of drug called an alpha-blocker that treats high blood pressure or prostate disease, such as tamsulosin (Flomax), doxazosin (Cardura), or prazosin (Minipress)
  • taking ritonavir (Norvir), an HIV medication

If any of the above factors applies to you, talk with your doctor. They may adjust your dosage of Viagra.

Get answers to some frequently asked questions about Viagra.

Is Viagra’s dosage based on weight?

No, the dosage of Viagra isn’t based on a person’s weight. Instead, Viagra’s dosage is based on your age, how well your kidneys and liver are working, and how well the drug works for your erectile dysfunction.

Does age affect Viagra dosage? If so, what would the dosage be for a 70-year-old vs. a 30-year-old?

Yes, your age is a factor in what dosage of Viagra is right for you.

As people get older, their heart, liver, and kidneys don’t work as well as they once did. This can cause an older adult’s body to break down drugs slower than a younger adult’s body. As a result, drugs stay longer in the body, which can raise the risk of side effects.

If you’re 65 years or older, your doctor may start you on a lower dosage of Viagra. The typical starting dosage of Viagra for a 70-year-old would be 25 milligrams (mg). For a 30-year-old who has no other medical conditions, the typical starting dosage would be 50 mg.

Regardless of your age, you’ll take your prescribed dose about an hour before sex.

If the prescribed dosage of Viagra works well for you and doesn’t cause bothersome side effects, you’ll likely continue taking it. If a dosage works well but causes bothersome side effects, your doctor may suggest a lower dosage. If a dosage doesn’t work to help you get or maintain an erection, your doctor may increase your dosage.

What would happen if I took a larger dose of Viagra than my doctor prescribed — for example, 150 mg or 200 mg?

You shouldn’t take more Viagra than your doctor prescribes. The maximum recommended dosage of Viagra is 100 mg per day. Taking higher doses of Viagra can increase your chances of having severe side effects, such as:

The dosage of Viagra you’re prescribed may depend on several factors. These include:

  • your age
  • the severity of your erectile dysfunction (ED)
  • how well Viagra works for your ED
  • other medications you take, if any
  • other conditions you may have (see “Dosage adjustments” under “What is Viagra’s dosage?”)

You’ll take Viagra by mouth about 1 hour before sexual activity. Viagra tablets may be cut in half, crushed, or swallowed whole.

You can take Viagra with or without food. But the drug may not work as quickly if you take it with foods containing a lot of fat, such as fried foods. In this case, Viagra could take up to an hour longer to start working.

Viagra is a medication that you’ll only take when you need it, about 1 hour before sexual activity. You don’t have to take it regularly for it to be effective.

If you forget to take Viagra an hour before sex, you can take it as soon as you remember. It starts working to improve erectile function as soon as 30 minutes after you take your dose. Its effects usually last about 4 hours.

If you need help remembering to take your dose of Viagra before sex, try setting an alarm or downloading a reminder app. Or ask your partner to remind you to take your dose about an hour before sex.

Don’t use more Viagra than your doctor prescribes. Using more than this can lead to serious side effects.

What to do in case you take too much Viagra

Call your doctor right away if you think you’ve taken too much Viagra. You can also call 800-222-1222 to reach the American Association of Poison Control Centers or use its online resource. But if you have severe symptoms, call 911 (or your local emergency number) immediately or go to the nearest emergency room.

The sections above describe the typical dosages provided by the drug’s manufacturer. If your doctor recommends Viagra for you, they will prescribe the dosage that’s right for you.

Remember, you shouldn’t change your dosage of Viagra without your doctor’s recommendation. Only take Viagra exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage.

Here are some questions you may want to discuss with your doctor:

  • How long should I give Viagra to work before my dosage should be increased?
  • Should I take a lower dosage of Viagra because of my other medications?
  • Can I take Viagra every day?
  • Would a higher dosage of Viagra increase my risk for side effects?

If you want up-to-date information about men’s health topics, including lifestyle tips, sign up for Healthline’s online newsletter.

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 another 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.