ED Pills

How Long Does Sildenafil Last: Effects in Your System and More

January 28, 2022

Medically reviewed by

David Culpepper, MD

Sildenafil citrate, more commonly known under the brand name Viagra®, is one of the most widely used and effective prescription medications for erectile dysfunction. It's been approved and on the market for over twenty years, and the name has become synonymous with sex.

In most cases, a single tablet of sildenafil (generic name) or Viagra is all it takes to improve blood circulation enough for a normal and easily sustained erection.

Just like all drugs, the active ingredient sildenafil has a specific active time in the body and half-life that determines how long it lasts, which can be influenced by age, diet, and health. Sildenafil's effects last about 4 hours for most men.

What Is Sildenafil?

Sildenafil is the generic name and active ingredient found in Viagra, an oral medication used to treat erectile dysfunction. It's part of a class of drugs called PDE5 inhibitors, along with tadalafil (Cialis®) and vardenafil (Levitra®).

In 1998, the pharmaceutical company Pfizer released Viagra after its approval by the Food and Drug Administration as the first oral medication for erectile dysfunction. Sildenafil can also be found under the brand name Revatio® (also sold by Pfizer) to treat a certain type of high blood pressure in the lungs called pulmonary hypertension.

How Does Sildenafil Work?

Sildenafil works by stopping a normal chemical reaction that causes blood to leave an erect penis.

Sildenafil is effective at blocking phosphodiesterase type 5 (PDE5), which is an enzyme that slows blood vessel dilation and essentially encourages blood to flow out of the penis.

Excess blood flowing into the penis is what causes an erection. The penis can hold 7 time its normal blood capacity during an erection. When sex or intimacy is over, the body normally allows PDE5 to help reverse an erection. It does this by breaking down cGMP, a key substance to attaining an erection.

When PDE5 is inhibited, levels of cGMP can remain elevated in the penis, which helps to relax the smooth muscles and arteries of the penis and encourage blood flow. This process is known as vasodilation.

What Are The Sildenafil Doses?

Sildenafil comes in doses of 25, 50 and 100 mg. All of these are taken in the 1-4 hours before sex, and your doctor will help determine what dose is right for you to start at. Most men will begin at 50 mg.

Does Sildenafil Start Working Immediately?

The amount of time that it takes for sildenafil to start working can depend on several factors, such as your own body's specific response to the drug, the size of the dose you take, and how much you've eaten before taking a tablet.

For the most part, sildenafil starts to work about 30 minutes after taking it. If you've taken the right dose for your situation, a majority of guys can successfully get an erection on sildenafil.

Sildenafil typically starts working much faster when it's taken on an empty stomach, as there is less chance of your digestive system slowing its absorption.

It’s important to note that taking sildenafil does not result in an erection alone and does require a source of sexual stimulation. Sildenafil helps men to develop and sustain erections, but only after they're aroused.

What Factors Affect Sildenafil?

There are a few external factors that can have a significant effect on how well sildenafil works and for how long it remains active in your body. Some of them include:

Taking It On A Full Stomach

Your diet can affect the amount of time that sildenafil lasts, as well as the amount of time that can take for sildenafil to start working.

If you eat a large meal with high-fat foods before taking sildenafil, it can slow down the absorption process and delay the effects of sildenafil. In fact, the FDA lists this as a caution in the official Viagra prescription label.

Drinking Alcohol or Taking Drugs

Drinking alcohol can also affect sildenafil. Since alcohol has a negative effect on the vascular system, drinking wine, beer, spirits, or other alcoholic beverage can result in sildenafil being less effective and even increase the risk of potential side effects.

Along with alcohol worsening the symptoms of erectile dysfunction, so too can other illicit drugs and marijuana. Chronic heavy drinking can result in damage to the liver, heart, and nerves while also reducing testosterone, all of which can contribute to erectile dysfunction.

Your Age

Your age can also have an effect on sildenafil’s activity. Older men may find that sildenafil remains active for much longer than the typical two to four hours, as their liver and metabolic system has become less effective at metabolization over the years.

The Dose

The dose of sildenafil you take will also play a role in its active life in your body. Most of the time, taking a higher dose of sildenafil (the largest available dose is 100 mg) will produce a more noticeable and longer lasting effect than taking a smaller dose of 25 or 50 mg.

Your Overall Health

Sildenafil is most effective when taken by a healthy individual. A healthy body, particularly a healthy heart and vascular system, is the best asset in helping to overcome erectile dysfunction. This is because for sildenafil to be most effective, your body still has to do some work.

The best way to get longer lasting and stronger erections is by improving blood flow and overall cardiovascular health. Some of the best ways to do that include:

Getting enough cardiovascular exercise. A sedentary lifestyle is a major risk factor for erectile dysfunction. According to one study, men who were inactive or moderately active (30 to 149 minutes of physical activity a week) had 40% to 60% higher odds of experiencing erectile dysfunction when compared to active men who were getting more than 150 minutes of physical exercise weekly.
Maintaining a healthy weight and avoiding or managing diabetes. In a 2012 study of 409 men between the ages of 40 and 91, researchers found that 74.5% of men in the largest waist group (39.4 inches or higher) had erection problems when compared to 50% of men in the middle group (35.4 to 39 inches) and 32% of the smallest group (35.4 inches of smaller). Weight and obesity is an ED risk factor.
Tobacco smoke contains dozens of toxins, such as acetone, arsenic, and carbon monoxide, that can cause damage to the linings of blood vessels throughout the body, including in the penis. In addition, nicotine is a known vasoconstrictor, a substance that reduces blood flow throughout your body. This means that even nicotine gum, patches, and smokeless tobacco will still have harmful effects and may result in erectile dysfunction.
There are some medications that list erectile dysfunction as a possible side effect. If you're experiencing ED while taking other medications for high blood pressure or antidepressants, talk with your doctor about whether it’s possible to switch to a different drug.

How Long Will The Effects Last?

Similar to the amount of time required for sildenafil to start working, the amount of time that it lasts depends on a few factors.

Most men will feel the effects of sildenafil for one to four hours. The drug may work for up to five hours, although it usually becomes less effective after three hours.

Below is a "pharmacokinetics" chart for Viagra, showing how long it remains in the system, on average. While it stays in the body for half a day, its effects typically dissipate by hours four or five.

A chart of Viagra's pharmacokinetics

Sildenafil vs. Other Medication

Although Viagra is still the most popular medication to treat erectile dysfunction, it's not the only option available. Other common drugs for erectile treatment include Cialis (tadalafil) and Levitra (vardenafil), both of which have similar effects as Viagra (sildenafil).

Sildenafil and vardenafil have essentially the same half-life. Both take about 30 minutes to begin working, and once the drug is absorbed by the body the effects usually last for roughly 4 hours.

Tadalafil, however, lasts for a substantially longer time than either sildenafil or vardenafil.

In most cases, one dose of tadalafil will take effect in roughly 30 minutes and provide noticeable effects for as long as 36 hours. As a result, tadalafil is the only prescribed medication that is suitable for taking in a lower daily dose (2.5 and 5 mg) as opposed to being taken as needed, at 5, 10 and 20 mg.

The Takeaway:

Sildenafil is the active ingredient in the widely popular brand name Viagra. In most cases, it can stay active in your blood for 4-5 hours. Sildenafil begins working in about 30 minutes. These timeframes are influenced by diet, age, and overall health.

The best way to increase the effectiveness and duration of sildenafil is by improving your diet, addressing underlying conditions like diabetes, and getting more exercise. For the most part, erectile dysfunction is the result of issues with blood flow in the body. Losing weight and improving cardiovascular health can help to overcome erectile dysfunction. They can also help to make prescription medications such as sildenafil more effective and longer lasting.