If Viagra doesn’t work as it should or stops working, you can take some steps to give the drug its best chance to work. Lifestyle changes and working with a therapist may also help.

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Viagra is a medication designed to help you get and maintain an erection if you have erectile dysfunction (ED).

The active drug is sildenafil, which is classified as a phosphodiesterase-5 inhibitor (PDE5 inhibitor) medication. PDE5 inhibitors are the first-line treatment for ED and may help approximately 3 out of 4 people with ED.

However, you may find that Viagra never works or it gradually stops working after you’ve used it successfully. If this happens, you’re not alone.

Keep reading to learn more about why Viagra may no longer be working and what you can do about it.

How does Viagra work?

Erections occur when there’s an increase in blood flow to your penis. If this blood flow is restricted or limited, however, you may experience erectile dysfunction (ED).

During sexual arousal, a protein called cyclic guanosine monophosphate (cGMP) is released. This increases blood flow to your penis to get or maintain an erection.

Once this is released, another protein called phosphodiesterase-5 (PDE5) breaks down cGMP, limiting blood flow to the penis. If you have ED, PDE5 may be breaking down cGMP too quickly.

Viagra works by temporarily inhibiting PDE5 from breaking down cGMP. This could help increase blood flow to maintain a stronger erection during sexual intercourse.

Here are some of the more common physical and emotional reasons why Viagra may not be working for you.

Improper dosing

The first thing to check if Viagra isn’t working is appropriate dosing. The most common dose of Viagra for ED is 50 milligrams (mg) which you take 1 hour before sexual activity.

However, this may not be enough for some people.

A healthcare professional could help you determine whether a higher dose of 100 mg suits you.

Learn more about Viagra dosage.

Malfunction of nerves

Dr. Myles Spar, who is chief medical officer at Vault Health, said that Viagra not working could mean that the issue isn’t vascular. This means that increasing blood flow isn’t helping.

“This can happen because of neuropathy or other issues,” he said.

Some neurological conditions that may affect the efficacy of Viagra may include:

Atherosclerotic heart disease

Viagra not working could mean there is a significant obstruction to the blood flow in your penile artery.

This may be a symptom of atherosclerosis or plaque in your arterial system, a risk factor for heart attack and stroke.

People with atherosclerotic heart disease have arteries that are plugged with cholesterol plaques or have lost their elasticity, according to S. Adam Ramin, MD, urologist and medical director of Urology Cancer Specialists.

In this situation, the arteries won’t respond to Viagra because it’s a vasodilator (a chemical that causes dilation) or because of the widening of the artery.

A healthcare professional will most likely perform a lipid screen if you have ED, even if you have no history of heart disease. The connection between atherosclerotic heart disease and ED is strong.

Penile erectile body disease

If you have a penile injury or Peyronie’s disease, the erectile body may not be able to accommodate increased blood flow, Ramin said.

Venous leak

If you have leaky valves, Ramin said, the blood may flow at an increased rate to your penis, but it will all leak out and not stay long enough to cause an erection.

It’s also possible that you can get an erection, but the venous leak means you’re unable to maintain it.

One cause of venous leak ED is Peyronie’s disease, which affects the connective tissue of the penis.

Psychological issues

Viagra may not work for everyone due to psychological issues, such as:

Other risk factors

For Viagra and other ED treatments to work, it’s important to address all of the risk factors that may be contributing to ED. These may include:

According to the American Urological Association (AUA), incorrect use of PDE5 inhibitors accounts for 56% to 81% of treatment failures.

Here are common mistakes to avoid and what you can do to help ensure Viagra has the best chance to work.

1. Avoid taking Viagra with a large meal or high fat meal

Viagra levels in your blood peak 1 hour after you swallow the tablet on an empty stomach.

If you eat a large or high fat meal and then take Viagra, the medication will lose its effectiveness. It may take longer to start working, according to Ramin.

2. Avoid taking Viagra with alcohol

Drinking alcohol, especially chronic (long-term) use, may contribute to ED. If Viagra is losing its effectiveness, you may want to consider limiting or eliminating alcohol to see if that helps.

3. Don’t expect Viagra to work just minutes before sex

“If you take Viagra and immediately try to have sex, it won’t work,” Ramin said.

“The most optimal way to take this medication is on an empty stomach, with no alcohol in your system, 1 hour before sex,” Ramin explained.

4. Don’t expect Viagra to work alone

Although many people may find Viagra highly effective, it can’t cause an erection on its own. For it to work, your body must be sexually aroused.

5. Make sure your testosterone levels get checked

Viagra and other PDE5 inhibitors won’t work well if your testosterone levels are too low.

If you have low testosterone, testosterone therapy alongside a PDE5 inhibitor may be a more effective treatment for ED, according to the AUA.

It’s important not to take exogenous (synthetic) testosterone if your natural levels are normal, as this may suppress the function of the testicles to produce the hormone. A doctor can test testosterone levels and evaluate this for you.

Be sure to use Viagra in several different scenarios

If you’ve taken Viagra in the most optimal situation more than five times and it hasn’t worked, then it may not be the right treatment for you, according to Ramin.

Before you decide Viagra isn’t for you, though, Dr. Myles Spar recommends using it at least once when masturbating to make sure it isn’t an issue with the person you’re with.

You may need to try Viagra up to 10 times to get comfortable with the steps of using it and how it makes you feel, as well as to understand how it may be affecting you.

Speak with a healthcare professional about your treatment so they can adjust dosing, make suggestions, and help you find what works.

Over time, Viagra may not be as effective in helping you get or maintain erections due to changes in your body or health.

If this happens, Spar said, you can try switching to another ED medication in the same class.

Other PDE5 medications approved by the Food and Drug Administration (FDA) for ED include:

The best alternative if Viagra isn’t working for you may be tadalafil (Cialis). It has a longer window of activity, meaning you can take it in a daily dose.

This can remove some of the psychological aspects and uncertainty of timing a pill before sex. Also, it can help you determine if PDE5 inhibitors suit your condition.

Doctors sometimes prescribe a combination of sildenafil and tadalafil if single-drug therapy isn’t working.

Several lifestyle changes may help relieve ED symptoms, such as:

If Viagra and other ED medications don’t work, consider working with a urologist or mental health specialist. They may recommend other ED treatment options, including:

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Does Viagra lose its effectiveness over time?

You may need to increase your dosage of Viagra over time due to changes in your body and health that may contribute to the progression of ED.

Can you build a tolerance to Viagra?

According to a 2015 review, it may be possible to build a tolerance (become less responsive to a drug) to Viagra. However, the authors note that the waning effects of Viagra may be due to a progression of ED rather than medication tolerance. More research is needed.

Viagra is a type of PDE5 inhibitor medication. PDE5 inhibitor medications are used as first-line treatment for ED.

Although PDE5 inhibitors tend to work well, they may not be effective for everyone. This may be due to underlying health conditions and lifestyle factors, among others.

Consider speaking with a healthcare professional if Viagra isn’t helping your symptoms of ED. They may recommend an alternative treatment that’s best for you.