How much Viagra® (sildenafil) should I take?

If you’re interested in giving Viagra a try to treat erectile dysfunction, getting the dose just right can be challenging. Too much, and you run the risk of side effects. Too little, and you may not reap the benefits. Viagra is available in three doses: 25mg, 50mg, and 100mg. While 50mg is the standard dosage, your healthcare provider will weigh factors including age, weight, health status, lifestyle, and more to determine the safest and most effective Viagra dosage for you. 

Continue reading to learn more about Viagra dosage.

Viagra is the brand name of sildenafil, an oral medication used to treat erectile dysfunction (ED). It's part of a group of drugs known as PDE-5 inhibitors. Viagra, released by Pfizer in 1998, was the first oral medication to be FDA-approved for treating erectile dysfunction. Other ED medications include Cialis (tadalafil) and Levitra (vardenafil).

There are three brand-name Viagra dosages: 25mg, 50mg, and 100mg. Generic sildenafil can also be prescribed in 20 mg, 25 mg, 50 mg, and 100 mg dosages. The maximum daily dose is 100 mg.

Your healthcare provider will prescribe the starting dose they believe is best for you. The Viagra dosage prescribed depends on the following:

• Age

• Overall and cardiovascular health

• Medical conditions

• Your reaction to the first dose

• How frequently you use the medication

Your healthcare provider may not get your Viagra dosage right on the first try. But it’s better to start with too little than too much. If you’re taking Viagra exactly as instructed and still don’t achieve the desired results, talk to your healthcare provider about changing your dosage.

Contrary to popular belief, the goal of ED medication is not to find the highest dose of Viagra you can handle, but to find a safe and effective dose. Your healthcare provider will strive to find the smallest amount of medicine necessary to achieve satisfactory erections, to reduce your risk of side effects.

Additionally, ED meds aren't one-size-fits-all. People have different needs, so talk with your healthcare provider about your expectations for Viagra, and be honest about how you and your partner(s) plan to use it. Be prepared to answer questions like:

• How many times a week do you plan to have sex?

• Are you willing to take Viagra at the appropriate time for the medication to work effectively?

• Are you concerned about any side effects of viagra?

For some, the 25 mg Viagra dosage is enough to have a great experience in the bedroom. Others need the maximum dose (100 mg) to achieve the same result. Work with your doctor to find the right dose based on your expectations, medical history, and symptoms, and report any side effects.

And above all—be honest about your medical history and always follow your healthcare provider's instructions. Don't change your dose without talking to your healthcare provider. More Viagra doesn't always mean a stronger erection, and higher doses can come with more side effects.

Viagra works by blocking phosphodiesterase type-5 (PDE-5), an enzyme that causes an erection to subside by encouraging blood to flow out of the penis. When PDE-5 is inhibited, the smooth muscles in the penis can relax, and the blood vessels can widen (a process known as vasodilation). That allows blood to flow more freely to the penis, improving erectile function.

Sildenafil is also sold as a drug for pulmonary hypertension under the brand name Revatio (generic name: sildenafil), although the doses of Revatio are different from Viagra.

You should take Viagra one to four hours before sexual activity. It won’t just give you an erection from nothing—you must be sexually aroused for it to help produce an erection.

As with any medication, you should always take Viagra or sildenafil as directed by your healthcare provider. You can take Viagra anywhere from 30 minutes to four hours before sexual activity. Don’t take Viagra more than once in a 24-hour period, or combine it with other PDE5 inhibitors. Taking too much increases your risk of side effects. 

You can take Viagra with or without food. However, avoid eating high-fat meals before taking the pill–research suggests fatty foods may impact how your body absorbs the medication, causing it to take longer to work.

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Common side effects of Viagra include:

• Dizziness

• Headache

• Flushing

• Upset stomach or indigestion

• Abnormal vision (such as increased sensitivity to light, blurred vision, or blue-tinted vision)

• Nasal congestion or runny nose

• Back pain

• Rash

• Muscle pain

Serious but less common adverse effects of Viagra include:

• Priapism (a prolonged erection that won't go away)

• Heart attack-like symptoms, such as chest pain

• Eye problems, such as sudden vision loss (a condition called non-arteritic ischemic optic neuropathy or NAION)

• Ringing in ears or hearing loss

• Seizures

• Swelling in your arms or legs 

If you experience any of these serious side effects, you should seek medical advice right away.

Some over-the-counter and prescription drugs can cause dangerous drug interactions with Viagra. For example, people taking nitrates for certain heart conditions should not take Viagra. Both nitrates (like nitroglycerin) and sildenafil affect nitric oxide levels, and the combination can lead to a potentially dangerous drop in blood pressure. Poppers, or amyl nitrites, should also be avoided when taking Viagra. 

If you take medications that affect the breakdown of sildenafil (like ritonavir, erythromycin, itraconazole, and ketoconazole), you may need a lower dose of sildenafil or Viagra.

Not everyone should take Viagra. Viagra lowers your blood pressure. If you already have low blood pressure or take medications to treat high blood pressure (like alpha-blockers), you may need to adjust your Viagra dose to avoid side effects.

Certain health conditions may impact your ability to absorb Viagra. Those include liver or kidney disease. If you have those conditions, you might need a smaller dose to take Viagra safely.

When it comes to medication, more is not necessarily better (or safer). If you’re concerned about erectile dysfunction, make an appointment with your healthcare provider. Take your Viagra as prescribed, and adjust as needed under the supervision of your healthcare provider, not on your own. 

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

April 07, 2023

Written by

Michael Martin

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.