Viagra® Dosage Guide: How to Find the Right Dosage for You

Struggling to get an erection after taking Viagra? Viagra (sildenafil) is available in three different doses. If you aren’t getting results from your current dose, talk to your doctor to see if switching to a higher dose could help you get and maintain a firmer, better erection. 

And if you’re experiencing side effects from Viagra, your doctor might recommend switching you to a lower dose.  

Below, we’ve listed the three available Viagra dosages. We’ve also listed what you can expect with each dosage, from erectile dysfunction treatment benefits to potential side effects. 

Viagra 50mg: A Typical Dose of Viagra®

The typical starting dose of Viagra for most patients is fifty milligrams. If you have erectile dysfunction and want to start using Viagra, this is probably the dose that your doctor will recommend and prescribe. 

In clinical trials, 74 percent of men who took a 50mg dose of Viagra experienced improved erections. If you have mild to moderate erectile dysfunction, this dose of Viagra may provide firmer, more reliable and longer-lasting erections when you’re sexually aroused.

It’s important to remember that Viagra only helps to treat erectile dysfunction when you have feelings of sexual arousal. Viagra is not meant to affect your sex drive when taken at 50mg or any other dosage.

Regardless of dosage, Viagra, on average, takes 30 to 60 minutes to start working. If you’ve been prescribed Viagra at a 50mg dose, it’s usually recommended that you take it about one hour before sexual activity. I

t’s possible to experience some side effects from Viagra — the most common ones include facial flushing, an upset stomach, nasal congestion, abnormal vision and headaches

For many men, the 50mg dose of Viagra will help provide relief from ED and improvement in sexual performance.

Viagra 100mg: Maximum Strength Viagra®

The maximum dose of Viagra approved by the FDA is 100mg, and your doctor may prescribe the 100mg dose if you have problems getting and maintaining an erection with the typical 50mg dose of the medication.

In clinical trials, 82 percent of men who took Viagra at a 100mg dose experienced improved erections. This dosage of Viagra is normally used if you have moderate to severe ED, or if you don’t respond to lower doses of the medication. 

Just like with the 50mg dose, it’s possible to experience side effects from 100mg Viagra, including facial flushing, an upset stomach, nasal congestion, abnormal vision, vasodilation and headaches. 

Even if you’re prescribed the 100mg version of Viagra, you should never take more than 100mg of Viagra in a single day. Exceeding the maximum recommended dosage of Viagra can increase your risk of experiencing cardiovascular side effects from the medication. 

Viagra 25mg: The Lowest Dose of Viagra®

At 25mg, this is the lowest FDA approved dose of Viagra. If you are unable to tolerate a higher dose, your doctor may prescribe you this lower dose. For instance, if you’re currently on medications that may reduce PDE5 metabolism, your doctor may determine that it is better for you to be on a lower dose of Viagra.

More specifically, Viagra 25mg may be prescribed for men that use antiretroviral drugs for HIV, alpha blockers for hypertension or other prescription drugs that can interact with Viagra and cause severe side effects at higher dosages.  

If you are over 65 years old or have liver cirrhosis or severe kidney impairment, your doctor may also start you on the 25mg dose. 

Frequently Asked Questions About Viagra® Dosages

Is Viagra® Safe to Use More Than Once a Day?

The maximum dosing frequency for Viagra (and generic medication containing sildenafil) is one time per day. Viagra is not designed for use more than once per day and can cause a range of health issues if overused. 

How Long Does Viagra® Last?

Viagra lasts for about four hours, although it’s usually recommended to take it about an hour before anticipated sexual activity. We’ve covered this topic in more detail in our guide to how long Viagra and other ED medications last

Do Lower Doses of Viagra® Stop Working Faster?

Sildenafil, the active ingredient in Viagra, has a terminal half-life of four hours, meaning it takes four hours for your body to metabolize half of the medication. This half-life does not change at a lower dose, meaning even the 25mg dose of Viagra should last for about four hours.

However, due to the age related changes in your body, you might notice the effects of the 25mg and 50mg doses of Viagra fading away earlier than the higher 100mg dose. If the effects of Viagra don’t last long enough, talk to your doctor about switching to a longer-lasting ED drug such as Cialis® (tadalafil).  

Does Age Affect Viagra®?

Age does not generally affect Viagra’s effectiveness. However, if you are older than 65 years old, your doctor may prescribe you a lower dose of Viagra, since there is evidence that after taking Viagra, older men will have higher amounts of it in their blood.  

Is Viagra® Affected by Weight?

While obesity and erectile dysfunction do appear to have a positive correlation, Viagra efficacy does not appear to be affected by weight, meaning you shouldn’t need to take a higher dose if you’re tall or have a heady build. Most of the time, your doctor will prescribe the 50mg dose of Viagra to start with even if you have an above-average BMI.

Is it Possible to Overdose on Viagra®?

Taking too much Viagra can cause your blood pressure to decrease significantly, which may result in fainting. If you’ve accidentally taken more than the recommended dose of Viagra, seek emergency medical care immediately. 

Viagra® Doesn’t Work For Me. Should I Increase the Dosage?

A variety of factors can cause Viagra to not work, from the severity of your erectile dysfunction to other health issues. If the 25 or 50mg dose of Viagra doesn’t work for you, talk to your doctor to see if changing to a higher dose is an option. 

Do not increase your Viagra dosage on your own. Instead, follow the instructions provided by your doctor. 

Learn More About Treating Erectile Dysfunction

Tired of dealing with erectile dysfunction? Viagra is one of four brand drugs approved by the FDA to treat ED. The others are Cialis® (tadalafil), Levitra® (vardenafil) and Stendra® (avanafil).

Our guide to using erectile dysfunction medication goes into more detail on how drugs like Viagra work, as well as what you can expect when you use them to treat erectile dysfunction and improve your sexual performance. 



This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.