Sildenafil for pulmonary hypertension

This leaflet is for parents and carers about how to use this medicine in children. Our information may differ from that provided by the manufacturers, because their information usually relates to adults. Read this leaflet carefully. Keep it somewhere safe so that you can read it again.

Name of medicine


Brand names: Viagra, Revatio

Why is it important for my child to take Sildenafil?

Pulmonary hypertension means high blood pressure in the lungs, which often occurs after heart surgery. Taking sildenafil will reduce the blood pressure in the lungs, so that they can work properly. Sometimes babies on ventilators need it in the neonatal unit.

What is Sildenafil available as?

  • Tablets: 20 mg (white, these contain small amounts of lactose), 25 mg, 50 mg, 100 mg (blue)
  • Liquid medicine can be ordered specially from your pharmacist (e.g. 50 mg in 5 mL)

When should I give Sildenafil

  • Sildenafil is usually given four times a day. This is usually first thing in the morning, at about midday, late in the afternoon and at bedtime. Ideally, these times should be about 4 hours apart (e.g. 8 am, midday, 4 pm, 8 pm).
  • Sildenafil is sometimes given three times a day. This should be once in the morning, once in the early afternoon and once in the evening. Ideally, these times are at least 6 hours apart, for example 8 am, 2 pm and 8 pm.

Give the medicine at about the same times each day so that this becomes part of your child’s daily routine, which will help you remember.

How much should I give?

Your doctor will work out the amount of Sildenafil (the dose) that is right for your child. The dose will be shown on the medicine label.

Your doctor may suggest that your child starts with a low dose. They may then increase the dose as your child gets used to the medicine and depending on how they respond to it. Your doctor will explain what to do. If you are not sure how much to give, check with your doctor, nurse or pharmacist.

It is important that you follow your doctor’s instructions about how much to give.

How should I give Sildenafil?


  • Tablets should be swallowed with a glass of water, squash or juice. Your child should not chew the tablet.

Dispersible Tablets

  • You can crush the tablet and mix it with a small amount of soft food such as yogurt, jam or mashed potato. Make sure your child swallows it straight away, without chewing.
  • You can dissolve the tablet in a small glass of water and add some juice/squash to hide the taste. Your child should drink it all straight away. Then add some more water or juice to the glass, swirl it round and ask your child to drink it. This makes sure they get all the medicine.

Liquid medicine

  • Shake the medicine well. Measure out the right amount using an oral syringe or a medicine spoon. You can get these from your pharmacist. Do not use a kitchen teaspoon as it will not give the right amount.

When should the medicine start working?

Your child will usually start the medicine while in hospital. It will start to work within a few days, although you may not notice any difference in your child. Your doctor will check that it is helping.

What if my child is sick (vomits)?

  • If your child is sick less than 30 minutes after having a dose of Sildenafil, give them the same dose again.
  • If your child is sick more than 30 minutes after having a dose of Sildenafil, do not give them another dose. Wait until the next normal dose.

If your child is sick again, seek advice from your family doctor, nurse, pharmacist, or hospital. They will decide what to do based on your child’s condition and the specific medicine involved.

What if I forget to give it?

If you miss a dose, wait until the next normal dose. Do not give the missed dose.

Never give a double dose of Sildenafil.

What if I give too much?

You are unlikely to cause harm if you give an extra dose of Sildenafil by mistake. If you are concerned that you may have given too much, contact your doctor or local NHS services (details at end of leaflet). Have the medicine or packaging with you if you telephone for advice.

Are there any possible side effects?

We use medicines to make our children better, but sometimes they have other effects that we don’t want (side effects).

Other side-effects you need to know about

  • Your child may feel light-headed or dizzy when they stand up, or may faint. Encourage them to stand up slowly, and to sit or lie down if they feel dizzy or lightheaded. If this happens often, contact your doctor to check your child’s blood pressure, as it may be too low.

  • Your child’s hair may become thinner and some may fall out. It should grow back when the medicine is stopped. Discuss this with your doctor at your next visit.

  • They may have a dry mouth. Eating citrus fruits (e.g. oranges) and taking sips of water may help. If this is still a problem after 2 weeks, contact your doctor for advice.

  • They may get a headache, feel tired, or become easily breathless. If this is still a problem after 2 weeks, or you are concerned, contact your doctor for advice.

  • Your child’s eyesight may become blurry or double and their eyes may become red and painful or sensitive to bright light. If this is still a problem after 2 weeks, or you are worried, contact your doctor.

  • They may get mild indigestion or stomach pain, or may feel sick (nausea) or be sick (vomit). If this is still a problem after two weeks, or you are worried, contact your doctor.

There may sometimes be other side effects that are not listed above. If you notice anything unusual and are concerned, contact your doctor. You can report any suspected side effects to a UK safety scheme at

Can other medicines be given at the same time as Sildenafil?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
  • Sildenafil should not be taken with some medicines. Tell your doctor or pharmacist about any other medicines your child is taking before giving Sildenafil.
  • Check with your doctor or pharmacist before giving any other medicines to your child. This includes herbal and complementary medicines.

Is there anything else I need to know about this medicine?

  • Do not suddenly stop giving sildenafil to your child as their symptoms may come back.
  • The liquid medicine does not keep for long once it has been opened. Write the date that you start it on the bottle and make sure you do not keep it past the expiry date given on the bottle.
  • You may have heard that Viagra (which is one of the brands for sildenafil) is used to treat erectile dysfunction (impotence). However, your child will be taking a much lower dose of it for pulmonary hypertension. Sildenafil may cause erections but this is rare and is nothing to worry about.

General advice about medicines

  • Try to give medicines at about the same times each day, to help you remember.
  • Only give this medicine to your child. Never give it to anyone else, even if their condition appears to be the same, as this could do harm.
  • If you think someone else may have taken the medicine, contact a doctor straight away.
  • Make sure that you always have enough medicine. Order a new prescription at least 2 weeks before you will run out.
  • Make sure that the medicines you have at home have not reached the ‘best before’ or ‘use by’ date on the packaging. Give old medicines to your pharmacist to dispose of.
  • If you are not sure a medicine is working, contact your doctor but continue to give the medicine as usual in the meantime. Do not give extra doses, as you may do harm.

Where should I keep this medicine?

  • Keep the medicine in a cupboard, away from heat and direct sunlight.
  • It does not need to be kept in the fridge.
  • Make sure that children cannot see or reach the medicine.
  • Keep the medicine in the container it came in.

Who to contact for more information?

Your doctor, pharmacist or nurse will be able to give you more information about Sildenafil and about other medicines used to treat pulmonary hypertension.

England: NHS 111

Tel 111

Scotland: NHS 24

Northern Ireland: NI Direct

Wales: NHS Direct

Tel 111 (free) or 0845 46 47 (2p per minute)

British Lung Foundation

Copyright disclaimer

Version [1]. © NPPG, RCPCH and WellChild, all rights reserved. Review by January 2014.

The primary source for the information in this leaflet is the British National Formulary for Children. For details on any other sources used for this leaflet, please contact us through our website,

We take great care to make sure that the information in this leaflet is correct and up-to-date. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something. This leaflet is about the use of these medicines in the UK, and may not apply to other countries. The Royal College of Paediatrics and Child Health (RCPCH), the Neonatal and Paediatric Pharmacists Group (NPPG), WellChild and the contributors and editors cannot be held responsible for the accuracy of information, omissions of information, or any actions that may be taken as a consequence of reading this leaflet.