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Sildenafil (Viagra)

4-minute read

Key facts

  • Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence).
  • Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection.
  • You should take sildenafil about an hour before planned sexual activity, so it has time to work.
  • Sildenafil is a prescription medicine, and not suitable for people with certain medical conditions — ask your doctor before taking this medicine.

What is sildenafil (Viagra)?

Sildenafil is a medicine used to treat erectile dysfunction (ED, also called impotence). It is sometimes known by its generic name sildenafil, and sometimes known by its trade name Viagra. Other brands of the same medicine are also available.

How does sildenafil work?

Sildenafil works by helping the blood vessels in the penis to relax. This allows more blood to flow in and cause an erection. If you have ED, this can make it easier to get an erection.

Sildenafil doesn’t cause erections on its own — sexual stimulation is still needed.

Sildenafil also does not:

How do I use sildenafil?

If you plan to use sildenafil, you should take it about an hour before planned sexual activity.

You can get an erection for up to 4 hours after taking sildenafil — meaning the ability to have an erection may last this long, but the actual erections will only last for a normal period of time.

You should not take any more than one sildenafil tablet in 24 hours. Do not take sildenafil if you are taking other medicines for ED.

Does sildenafil have side effects?

The most common side effects of sildenafil include:

These side effects usually go away after a few hours.

Very occasionally, sildenafil can cause a painful erection or an erection that won’t go away (priapism).

If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department. Prolonged erections can be dangerous.

Who shouldn’t take sildenafil?

Sildenafil may not be safe to take for people with certain medical conditions including:

It can also interact with many other medicines, particularly nitrates (used in heart disease), amyl nitrite and blood pressure medicines. People who use nitrates in any form or are being treated for pulmonary hypertension should not take sildenafil.

How can I buy sildenafil?

You need a prescription from a doctor to obtain sildenafil. You can buy it from a store-based pharmacy or reputable online pharmacy with a prescription.

Some people buy sildenafil online without a prescription. This isn’t a good idea, as you can’t be sure whether these pills contain the medicine or are counterfeit. Counterfeit medicines can be very dangerous.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

What is ‘Viagra for women’?

Viagra is not for use by females. If you have heard about ‘female Viagra’, it is probably referring to a medicine called flibanserin (also known by its brand name, Addyi). This medicine has been approved in the United States to treat premenopausal females who have low sexual desire.

Flibanserin is not approved in Australia. This medicine can interact with other medicines and supplements, causing potentially serious side effects. It is not recommended for use in Australia.

What alternatives can I use for erectile dysfunction?

There are many other treatments for erectile dysfunction.

If you are having problems with your sexual function, see your doctor for a diagnosis and to make sure there’s nothing else going on with your health. Your doctor will discuss the best treatment plan for you.

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Last reviewed: March 2023


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