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 is part of a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors. They work 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, sildenafil 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:

• cure erectile dysfunction (ED)
• increase your sexual desire
• protect from sexually transmitted infections (STIs)
• serve as contraception

What is sildenafil used for?

Sildenafil (Viagra) is used to try to address the symptom of erectile dysfunction.

Sildenafil (under another trade name, Revatio) is used to treat pulmonary arterial hypertension (high blood pressure in your lungs).

What forms of sildenafil are available?

Sildenafil (Viagra) is available as a tablet. Different doses are available. Your doctor will prescribe you the appropriate dose for your situation.

What are the possible side effects or risks of sildenafil?

The most common side effects of sildenafil include:

• headache
• indigestion or heartburn
• dizziness
• back pain
• muscle aches
• flushed skin
• stuffy or runny nose

These side effects usually go away after a few hours.

More serious side effects include:

• migraines
• vision impairment or loss
• loss of consciousness or seizures
• hearing loss
• allergic reaction

If you notice any unusual symptoms or side effects that worry you, tell your doctor.

Very occasionally, sildenafil causes a painful erection or an erection that won't go away (priapism).

How do I take sildenafil?

You should take sildenafil exactly as your doctor has prescribed. Take the tablet with a glass of water.

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

The time it takes for sildenafil to start working varies between people. It usually starts working in 30 to 60 minutes. The effects of the medicine can last for up to 4 hours. This means that the ability to have an erection can occur during this 4 hour period, but the actual erection will only last for a normal period of time.

You may find that it takes longer to work if you have a full stomach.

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.

Who shouldn't take sildenafil?

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

• a past history of stroke or heart attack in the last 6 months
• heart disease
• retinitis pigmentosa (an eye disease)

It can also interact with many other medicines, particularly:

• nitrates (used to treat chest pain)
• amyl nitrite
• blood pressure medicines

Taking sildenafil while taking these medicines can cause a sudden drop in your blood pressure that is hard to treat. People who use nitrates in any form or are being treated for pulmonary hypertension should not take sildenafil.

Let your doctor know about any medical conditions and/or medicines that you are taking.

When should I see my doctor?

You need a prescription from a doctor to get 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.

If you have any concerns or questions about taking sildenafil, speak to your doctor or pharmacist. If you are not finding sildenafil effective in treating your erectile dysfunction, speak to your doctor about changing the dose or treatment option.

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 an approved prescription medicine in Australia. This medicine can interact with other medicines and supplements, causing potentially serious side effects.

Are there any alternatives to this medicine?

There are many other treatments for erectile dysfunction, including medicines and medical devices. This also includes other medicines in the PDE5 inhibitor class.

You can read more about 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.

Resources and support

It is important to ask about your treatment or medicine, to help you understand your options. Read our guide to important questions to ask your pharmacist or doctor before taking a medicine.

You can also check the healthdirect's medicines section for more information about sildenafil.

• See the Healthy Male website for more information about erectile dysfunction and its treatment.
• Mensline is a free telephone and online counselling service. Call 1300 78 99 78 for help 24 hours a day, 7 days a week, or chat online.
• Read more on male sexual health on the Sexual Health Australia website.
• The Australian Government provides information on how smoking affects erectile dysfunction.

Do you prefer to read in languages other than English?

True provides multilingual information on men's sexual and reproductive health.

Looking for information for Aboriginal and/or Torres Strait Islander people?

The Australian Indigenous HealthInfoNet has sexual health information and resources.