Sildenafil will be prescribed for you by a specialist doctor.
Every time you collect a supply, check that you have been given the same brand of tablets as before. If the appearance is not the same as usual, please speak with your doctor or pharmacist.
Do not drink grapefruit juice while you are on sildenafil.
The most common side-effects are headache, sickness, flu-like infections, diarrhoea and nosebleeds.
About sildenafil for pulmonary arterial hypertension (PAH)
|Type of medicine||A vasodilator antihypertensive medicine|
|Used for||Pulmonary hypertension|
|Also called||Revatio®; Granpidam®|
|Available as||Tablets and oral liquid medicine|
Pulmonary arterial hypertension (PAH) is a condition where there is too high a blood pressure in the arteries which supply blood to your lungs from your heart. The arteries become narrowed so your heart has to work harder to pump blood to your lungs.
Sildenafil relaxes the muscles in the walls of the arteries, allowing the blood vessels to become wider. This reduces the pressure in the arteries and allows blood to flow more easily through them. In turn, this increases the supply of blood to your lungs and improves your ability to do physical activities. Sildenafil will be prescribed for you by a doctor who is a specialist.
Another brand of sildenafil tablets called Viagra® is used by men for a completely different condition called erectile dysfunction. There is another medicine leaflet called Sildenafil for erectile dysfunction which gives more information about this.
Before taking sildenafil for PAH
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking sildenafil it is important that your doctor knows:
- If you are pregnant or breastfeeding.
- If you have any other heart or blood vessel disease.
- If you have low blood pressure.
- If you have a condition which causes bleeding, such as a stomach ulcer.
- If you have had an eye condition causing loss of vision.
- If you have any problems with the way your liver works, or any problems with the way your kidneys work.
- If you have had a stroke or a heart attack.
- If you have any disease, injury or deformity of your penis.
- If you have sickle cell disease.
- If you have ever had bone marrow cancer or leukaemia.
- If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines. It is important that your doctor knows if you are using a nitrate medicine to treat angina pain, or if you are using a recreational drug called a 'popper'.
- If you have ever had an allergic reaction to a medicine.
How to take sildenafil tablets for PAH
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack, along with any information you have been given by your hospital. The manufacturer’s leaflet will give you more information about Revatio® and will provide you with a full list of the side-effects which you may experience from taking it.
- Take sildenafil exactly as your doctor tells you to. The usual dose for adults is one 20 mg tablet three times daily (6-8 hours apart), but your doctor will tell you what dose is right for you. Try to take your doses at the same times of day each day, as this will help you to remember to take the tablets regularly.
- Swallow the tablet with a drink of water. You can take sildenafil either before or after food.
- If you forget to take a dose, take it as soon as you remember. Try to take the correct number of doses each day but do not take two doses at the same time to make up for a missed dose.
- If you are giving sildenafil liquid medicine to your child, shake the bottle well before you measure out the dose. Use the oral dose syringe provided in the pack to give the correct dose. The mixture will have been made up freshly by your pharmacy when it is supplied to you. Store the bottle in a refrigerator. It will keep for four weeks.
Instructions for using the dosing syringe with Revatio® oral suspension
- Shake the bottle well for at least 10 seconds.
- Remove the bottle cap and make sure the plastic adaptor is fitted into the top of the open bottle.
- Insert the tip of the dosing syringe into the adapter.
- Turn the bottle (with the syringe connected to it) upside down.
- Gently pull out the plunger of the syringe so that the solution fills the syringe to the mark which corresponds to your dose.
- Turn the bottle the correct way up again and remove the syringe from the bottle.
- Put the tip of the syringe into your (or your child's) mouth and gently push the plunger so that the liquid is released.
Getting the most from your treatment
- Try to keep your regular appointments with your doctor so your progress can be checked.
- Do not drink grapefruit juice while you are on sildenafil. This is because a chemical in grapefruit juice is thought to increase the amount of sildenafil in your bloodstream. This makes side-effects more likely.
- Each time you collect a new supply of tablets from your pharmacy, check to make sure that the tablets look to be the same as you have had before. There is another brand of sildenafil tablets available for a different condition and these are not suitable for you. If you are unsure about your supply, please ask your pharmacist to check the tablets for you.
- Treatment with sildenafil for PAH is usually long-term. Continue to take the tablets unless you are advised otherwise by your doctor. Stopping treatment suddenly can cause problems, so if it becomes necessary for you to stop taking sildenafil, your doctor may want you to reduce your dose gradually.
- If you are due to have an operation or some other medical treatment, it is important that you tell the person carrying out the treatment that you are on sildenafil.
- If you buy any medicines 'over the counter', always check with a pharmacist that they are suitable for you to take with sildenafil.
Can sildenafil cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with sildenafil. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Common sildenafil side-effects||What can I do if I experience this?|
|Headache, muscle aches and pains||Ask your pharmacist to recommend a suitable painkiller|
|Diarrhoea||Drink plenty of water to replace any lost fluids|
|Indigestion, stomach discomfort||Stick to simple meals - avoid rich or spicy foods|
|Dry mouth||Try chewing sugar-free gum or sucking sugar-free sweets|
|Eyesight problems, feeling dizzy||If this happens, do not drive or use tools or machines. If the problems with your eyesight start suddenly or continue, speak with your doctor for advice|
|Cough, cold and flu-like infections, high temperature, flushing, swollen feet or ankles, difficulties sleeping, feeling anxious, tingling skin or burning sensations, feeling shaky, hair loss, anaemia, nosebleeds||If any of these become troublesome, speak with your doctor for advice|
Important: there are some other side-effects which occur less commonly than those listed above, but if you experience them, you should contact a doctor for advice as soon as possible. These are:
- Any sudden problems with your hearing or eyesight.
- If you have an erection which lasts for four hours or more.
If you experience any other symptoms which you think may be due to sildenafil, please speak with your doctor or pharmacist for further advice.
How to store sildenafil
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
- If you have been given liquid medicine, this will have been made up by the pharmacy and lasts for four weeks stored in a fridge. Make sure you check the expiry date on the bottle and do not use it after this date.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Revatio® 20 mg film-coated tablets; Pfizer Limited, The electronic Medicines Compendium. Dated April 2018.
Manufacturer's PIL, Revatio® 10 mg/ml powder for oral suspension; Pfizer Limited, The electronic Medicines Compendium. Dated April 2018.
British National Formulary, 75th Edition (Mar 2018); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.