Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 1/21/2021
Sildenafil, the active ingredient in Viagra®, is an FDA-approved medication for treating erectile dysfunction (ED).
Although sildenafil doesn’t cure erectile dysfunction, it does make it easier to get and maintain an erection. Sildenafil and other medications for ED work by increasing blood flow to the penis when you feel sexually aroused.
Like many other medications for ED, sildenafil comes in several different dosages. Finding the right dosage for you will help you get the best results from sildenafil while reducing your risk of experiencing side effects.
Below, we’ve explained how sildenafil works to treat ED and listed the most common dosages for this medication. We’ve also provided actionable tips to help you choose the most effective sildenafil dosage for your needs.
Sildenafil is the active ingredient in Viagra. It’s available under a variety of brand names and as a generic medication(e.g.generic Viagra) for erectile dysfunction and pulmonary arterial hypertension (PAH).
Sildenafil comes in several dosages, from 20mg all the way up to a maximum dosage of 100mg per tablet.
It generally takes between 30 minutes and 60 minutes for sildenafil to work, with the effects of the medication usually lasting for four hours or longer.
Since ED can vary in severity, there’s no one-size-fits-all dosage for sildenafil and other ED medications. If you have mild to moderate ED, you may notice major improvements in your sexual performance from a relatively low dosage of sildenafil.
On the other hand, if you have severe ED, or ED that’s caused by a medical condition that affects your blood flow, you may need to use a higher dosage.
While a higher dosage of sildenafil may be the most effective, taking too much sildenafil can also increase your risk of experiencing side effects.
Sildenafil belongs to a class of medications referred to as PDE5 inhibitors. It works by blocking the actions of cGMP-specific phosphodiesterase type 5 — an enzyme that regulates the flow of blood to certain tissue in your body, including your penis.
Erections are all about blood flow. When you’re sexually aroused, your nervous system signals to the muscles of your penis. As these muscles relax, blood flows to the corpora cavernosa — a pair of sponge-like masses of erectile tissue that allow you to get an erection.
As blood flows in, the tunica albuginea — a type of membrane that surrounds the erectile tissue of your penis — contracts, trapping blood inside your erectile tissue and allowing you to maintain an erection during sex.
By inhibiting the action of PDE5, medications like sildenafil improve blood flow to your penis and make it easier to get and stay hard when you’re sexually aroused.
Sildenafil is available in several different dosages. The standard dosage for ED is usually 50mg taken about one hour before sexual activity. This may be adjusted to 25mg or 100mg based on the severity of your ED and your response to sildenafil.
Some versions of sildenafil come in 20mg tablets. This dosage was originally developed to treat pulmonary arterial hypertension (PAH), but is sometimes used off-label to treat ED.
There’s no “ideal” dosage of sildenafil for everyone. If you only have mild ED, you may find that a low dosage is more than enough to improve your symptoms and help you have sex without worrying your erection issues.
If you have more severe or persistent ED, your healthcare provider may prescribe sildenafil at a higher dosage.
We’ve listed the most common dosages of sildenafil below, along with more information on the effects you can expect from each one.
A dosage of 50mg sildenafil is typical for erectile dysfunction. If you sometimes find it difficult to get or sustain an erection during sex, your healthcare provider may recommend starting sildenafil at this dosage.
Most men with ED notice improvements in their erections and sexual performance from a 50mg dosage of sildenafil.
For example, a series of two studies looked at the effects of 50mg sildenafil in men with erectile dysfunction.
After taking sildenafil at this dosage, 71 percent of the men that took part in the study developed an erection in 30 minutes or less. After 45 minutes had passed, 82 percent of the men achieved an erection.
On average, the men’s erections lasted for a median time of 19.5 minutes after using sildenafil, compared to zero minutes for men that received a non-therapeutic placebo.
100mg is the maximum recommended dosage of sildenafil for ED. Your healthcare provider may prescribe sildenafil at this dosage if you have severe, persistent ED that doesn’t improve when you use sildenafil at a lower dosage.
25mg is a relatively low dosage of sildenafil. Your healthcare provider may prescribe sildenafil at this dosage if you only have mild erectile dysfunction, or if you experience side effects when you take sildenafil at a higher dosage.
Some forms of sildenafil come as a 20mg tablet. These are often generic forms of Revatio® — a version of sildenafil used to treat pulmonary arterial hypertension (PAH).
Sildenafil is a safe and effective medication for most people. However, like other medications, it can cause side effects. The most common side effects of sildenafil are headache, nausea, rash, dizziness, nasal congestion, flushing, abnormal vision and indigestion.
Data from clinical trials shows that the risk of experiencing side effects from sildenafil increases with dosage.
For example, headache (the most common side effect of sildenafil) was reported by 16 percent of people at a dosage of 25mg, 21 percent at a dosage of 50mg and 28 percent at a dosage of 100mg in clinical trials.
Other side effects, such as flushing, indigestion, nasal congestion and others also occurred at a higher rate as dosage increased.
Our guide to sildenafil side effects goes into more detail on the side effects you may experience while using this medication. If you’re prone to side effects from sildenafil, taking a lower dosage, such as 25 or 50mg, may be the best option for you.
In addition to using the correct dosage, there are several things that you can do to improve your results from sildenafil. Try to:
Try to take sildenafil an hour before sex. Sildenafil usually starts to work in 30 minutes to 60 minutes. For best results, try to take your dosage of sildenafil around one hour before you plan to have sex.
Avoid high-fat foods while you use sildenafil. You can take sildenafil with food or on an empty stomach. However, it’s best to avoid taking it with a high-fat meal, as this can slow down absorption and make sildenafil take longer to work.
Limit your alcohol consumption. Although it’s generally safe to drink a small amount of alcohol before taking sildenafil, drinking excessively may reduce the effectiveness of sildenafil and increase your risk of experiencing side effects.
Our full guide to sildenafil and alcohol goes into more detail on the effects of alcohol on ED medications.
Take other steps to improve your erectile health. Erections are closely linked to good cardiovascular health. In addition to using sildenafil, it’s important to prioritize habits that keep your body in good condition.
From maintaining a healthy body mass index to avoiding nicotine and alcohol, our guide to naturally improving your erections lists a variety of steps that you can take to improve your erectile health the natural way.
Consider reducing your porn consumption. If you’re young and physically healthy but still occasionally get erectile dysfunction, it’s possible that your consumption of porn may play a part.
While research is limited, some studies have found that regular use of porn may cause a form of ED called porn-induced erectile dysfunction.
If you watch porn often, try taking a break from porn to see if your erections and real-life sexual performance improve.
In addition to sildenafil, several other medications are approved by the FDA for treating erectile dysfunction. Some of these last longer than sildenafil, while others are less likely to cause side effects. Other medications for ED include:
Vardenafil. The active ingredient in Levitra®, vardenafil typically lasts for slightly longer than sildenafil.
Beyond using medication, making changes to your habits and lifestyle can help to improve your blood flow and erectile health. We’ve talked more about lifestyle and natural options for treating ED in our guide to ED home remedies.
If you’re one of the tens of millions of men affected by erectile dysfunction, using medication like sildenafil can help to improve your erections, enhance your sexual performance and give you a noticeable confidence boost in the bedroom.
Since ED can vary in severity, there’s no “right” dosage of sildenafil for everyone. Instead, your healthcare provider will choose a dosage based on the severity of your ED, your general health and other factors.
Most of the time, your healthcare provider will prescribe sildenafil at a dosage of either 25, 50 or 100mg.
If the initial dosage you’re prescribed isn’t effective, or if you experience side effects, make sure to talk to your healthcare provider. It’s common and normal to adjust your sildenafil dosage over time to provide the best results with as few side effects as possible.