Updated April 2024

What is Sildenafil?

Download button - information sheetSildenafil (brand name: Revatio®) belongs to a group of medicines called phosphodiesterase inhibitors. It works by relaxing the smooth muscles of the blood vessels in your body. This increases blood flow and reduces blood pressure to your body organs. It is used to treat pulmonary hypertension (increased pressures in arteries supplying the lungs) and to manage ulcers on the fingers and toes in Raynaud’s phenomenon associated with scleroderma. Sildenafil is the most common type of phosphodiesterase inhibitor prescribed with others including tadalafil.

Sildenafil is also used in other conditions such as erectile dysfunction.

Important things to remember

  • While taking sildenafil you must see your specialist regularly to ensure the treatment is working and to minimise any possible side effects.
  • If you are worried about any side effects, you should contact your specialist as soon as possible.
  • It is important to tell your doctor if you are prescribed other medicines such as nitrates or are being treated for chest pain as some medicines can interact with sildenafil to cause serious side effects.

What benefit can you expect from your treatment?

Sildenafil is a medicine used to treat pulmonary hypertension. Sildenafil lowers the blood pressure by relaxing the blood vessels in the lungs. You may notice improvement in breathlessness, palpitations and/or exercise tolerance within a few weeks of starting treatment with sildenafil although in some cases it can take longer. 
Sildenafil may prevent ulcers or improve healing of ulcers on fingers and toes.
Benefits of continuing sildenafil will be reviewed at each clinic appointment, and it is important to let your treating specialist know of any new medicines or conditions at each visit.

Stopping sildenafil

If you stop or delay your sildenafil treatment, your condition may get worse. Keep taking sildenafil, unless advised by your specialist to stop or unless serious side effects occur (see side effects).
If you stop sildenafil for any reason, you must contact your specialist. 

How will your condition be monitored?

You will be assessed by your specialist to decide if the treatment is working. Before starting the treatment of pulmonary hypertension, you may have to undergo testing in the form of an echocardiogram (ultrasound scan of the heart), a 6-minute walk test and right heart catheterisation. These may be repeated to monitor your condition.

How is sildenafil given?

Sildenafil is taken by mouth in tablet form swallowed whole with a glass of water. Do not crush, break or chew the tablet, unless advised to by your doctor or pharmacist. It can be taken with or without food.

What is the dosage?

The usual dose given to treat pulmonary hypertension is 20mg three times daily, however your treating specialist may decide to give you higher doses.

Can other medicines be taken with Sildenafil?

Sildenafil is usually given alongside other medicines to treat pulmonary hypertension. Some medicines if taken with sildenafil may cause serious side effects (see precautions).

Are there any side effects?

You might experience side effects with your treatment. Tell your doctor if you notice any side effects that you think might be caused by sildenafil.

Most common possible side effects

Most commonly reported side effects are headache (1 in 10 people), dizziness/light headedness, facial flushing, blurred vision, stuffy nose, nausea.

Less common or rare possible side effects

Less commonly reported side effects include rash or allergic reaction causing swelling of eyes, lips or throat (1 in 100), vomiting, rapid heartbeat, low blood pressure, ringing in the ears, dry mouth, blood in the urine and nosebleed. 

Rare, reported side effects (less than 1 in 1000) include stroke, heart attack, loss of vision or bleeding at back of eye, loss of hearing, sustained penile erection, fits or seizures, severe peeling and swelling of skin and eyes.

What precautions are necessary?

Precautions with other diseases

Do not take sildenafil if you have:

  • angina (chest pain), severe heart or liver problem
  • recently had a stroke or heart attack
  • low blood pressure causing fainting
  • rare inherited eye condition (such as retinitis pigmentosa)
  • ever had vision loss due to a condition called non-arteritic anterior ischemic optic neuropathy.
  • allergy to sildenafil.

Talk to your doctor before taking sildenafil if you have sickle cell anaemia, leukemia (cancer of blood cells), multiple myeloma or structural deformity of penis.

Precautions with other medicines

Do not take sildenafil if you are:

  • Taking medicine called nitrates used to treat angina or amyl nitrite (“poppers”) as combination may lead to a dangerous fall in blood pressure or lead to an angina attack.
  • Taking riociguat to treat pulmonary hypertension as the combination may cause low blood pressure.

Talk to your doctor if you are taking a protease inhibitor (used to treat HIV) as the dose of sildenafil may need to be lowered, alpha-blockers used to treat high blood pressure or prostate enlargement may cause dizziness or light headedness.  

Use with alcohol

You are advised not to drink excessive amounts of alcohol while taking sildenafil.

Driving and using machines Sildenafil can cause dizziness and can affect vision. You should be careful before you drive or use machines when starting sildenafil.

Use in pregnancy and when breastfeeding 

Any woman who is taking sildenafil to treat pulmonary hypertension and is planning pregnancy should speak to her treating specialist to discuss her medicine. While breastfeeding, very small amounts of sildenafil may pass into breastmilk, however it is unlikely to cause any side effects in babies. Speak to your specialist for further information.

How to store sildenafil

Store sildenafil in a cool dry place, away from reach of children. Do not store above 30°C.