How Long Does it Take Viagra to Work?

By Sarah Malka, MD
Medically reviewed
November 9, 2021

If you suffer from erection problems, you are not alone.

As many as one-third of men suffer from erectile dysfunction—impotence, or the inability to get or keep an erection.

Older men with heart disease, hypertension, or diabetes, or who take certain medications like antidepressants, are at a greater risk of erection problems, however anyone at any age can experience them.

One study from 2013 found that around 25 percent of erectile dysfunction (ED) patients were 40 or younger

Viagra (sildenafil) is a brand-name prescription drug approved by the FDA that is primarily used to treat ED.

In some circumstances, Viagra is prescribed for pulmonary arterial hypertension.

Sildenafil citrate is the generic version of Viagra. It is identical in chemistry to viagra and works exactly the same.

For ED sufferers, Viagra can be taken before sex to help overcome ED.

In this article, I’ll explain how long it takes for Viagra to start working, and how long it stays in your system.

I’ll also discuss when you should talk to a doctor about your ED.

When Does Viagra Start Working?

Viagra is one of four FDA-approved, brand-name prescription medications for treating ED in men.

The active ingredient in Viagra is sildenafil citrate, a phosphodiesterase-5 inhibitor (PDE-5 inhibitor) that blocks a particular enzyme from breaking down a molecule called cyclic guanosine monophosphate (cGMP).

Basically, Viagra works by expanding the blood vessels that go to the penis.

This increases blood flow, improving your ability to get and maintain an erection when you’re sexually aroused.

If you are taking Viagra to treat ED, follow your prescriber’s instructions.

Take it as needed before sexual stimulation, and avoid taking it more than once within 24 hours.

After taking Viagra, you can expect the medication to take effect in 30-60 minutes.

Though you can take Viagra any time from four hours to 30 minutes before sexual activity, patients see the best results when they take Viagra about an hour before sexual stimulation.

If you take Viagra with a heavy, high-fat meal, the medication may take longer to start working in your system, or may not work as well.

It is best consumed with water on an empty stomach.

Drinking alcohol with Viagra may make it less effective.

If you have certain health conditions or are taking other medications, your provider may recommend you take Viagra less frequently.

It is not recommended for men who have low blood pressure, uncontrolled high blood pressure, chest pain, or heart problems of any kind, or who are taking certain cardiac medications.

How Long Does Viagra Stay in Your System?

How long Viagra lasts will depend on your dose.

Viagra is available as a pill in 25 mg, 50 mg, and 100 mg doses.

All three strengths are only available by prescription after consultation with a licensed prescriber.

Your dosage will depend on your age and overall health, the severity of your condition, how well you respond to the drug, as well as any other medications you take.

A “normal” Viagra dose is 50 mg, which resulted in improved erections for 74 percent of men in clinical trials.

A 25 mg pill is an adequate dose for many patients, though.

On average, Viagra stays in your system for 4-8 hours, and it is most effective within the first 1-4 hours after taking it. 

Erections lasting longer than four hours can be a sign of a serious side effect—if Viagra is working for that long, visit and urgent care center or emergency room.

Take Viagra only as directed by your provider.

Do not take more or less than your allocated dose and never more frequently than as prescribed—this can cause serious or even life-threatening side effects. 

Get an erectile dysfunction prescriptions for as low as $0.90 per dose.

Get Started

When to See a Doctor or Healthcare Professional

Before taking Viagra or sildenafil, consult with a licensed healthcare provider to determine if this is the right medication for you.

There are several medications available for erectile dysfunction and it is important your provider is aware of any underlying health conditions you may have including any medicines you are currently taking to help you pick the safest and most effective option.

If you’re taking Viagra, you should visit a healthcare professional immediately if you experience serious side effects such as vision problems or an erection that lasts longer than four hours.

You should also visit an urgent care or ER right away if any of the following, more rare symptoms manifest:

  • Difficulty breathing
  • Clumsiness or unsteadiness
  • Ear pain 
  • Buzzing or ringing in the ears
  • Redness, swelling, or sores on the mouth, tongue, or lips
  • Rectal bleeding
  • Trembling and shaking 
  • Vomiting 
  • Exhaustion
  • Painful urination

More common mild to moderate side effects of Viagra include:

How K Health Can Help

Since Viagra is a brand-name medication, it costs more than sildenafil, the generic option.

Viagra costs approximately $70 per pill, while sildenafil costs around $40 per pill at your local pharmacy.

They are chemically the same and are equally effective.

You can get sildenafil from K Health for as low as $1.80 per pill.

Need a prescription?

K Health can help you get a prescription for Viagra today.

Download K to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

Frequently Asked Questions

When should I take Viagra for best results?
Take Viagra 30-60 minutes before sexual stimulation for best results. Take it on an empty stomach with a glass of water. You can expect the drug to work effectively with sexual arousal within 30 minutes to four hours of taking it.
Can Viagra keep you hard after ejaculating?
No, but Viagra can reduce the refractory period, meaning it can help you get an erection again faster after orgasm.
Can you make Viagra kick in faster?
There is no way to speed up the amount of time it takes Viagra to kick in, but there are certain things you can do to improve its absorption in your bloodstream. Take Viagra on an empty stomach or with a light meal for best results.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.