Zafirlukast for asthma prevention (prophylaxis)

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.

Zafirlukast should not be used during an acute asthma attack (sudden onset of wheezing and breathlessness). Use your child’s reliever medicine (usually a blue salbutamol inhaler).

In an acute asthma attack – if your child’s asthma symptoms are not getting better or they are still struggling to breathe after taking their blue salbutamol inhaler, take them to hospital straight away.

Name of medicine


Brand name: Accolate®

This leaflet is about the use of zafirlukast for the treatment of asthma. It is taken regularly in order to prevent attacks. (This is sometimes called asthma prophylaxis.)

Why is it important for my child to take Zafirlukast?

Zafirlukast belongs to a family of medicines called leukotriene receptor antagonists. Leukotrienes can cause inflammation in the lungs, which can act as a trigger for asthma. Zafirlukast blocks this effect and so should reduce the number of attacks of wheezing or coughing. Your doctor will probably recommend that you continue to give your child their steroid inhaler.

Zafirlukast will not reduce wheezing or breathlessness during an acute asthma attack – your child should use their ‘reliever’ inhaler for this (this is often a blue salbutamol inhaler).

What is Zafirlukast available as?

Tablets: 20 mg; these contain small amounts of lactose

When should I give Zafirlukast

Zafirlukast is usually given twice each day, once in the morning and once in the evening. Ideally, these times are 10–12 hours apart, for example some time between 7 and 8 am, and between 7 and 8 pm.

How much should I give?

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

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

How should I give Zafirlukast?


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

When should the medicine start working?

Zafirlukast usually needs to be given with your child’s steroid inhaler to prevent asthma and wheeze. It does not work straight away but your child should start to wheeze less and to need less reliever medicine a few weeks after starting treatment. Continue to give the medicine twice each day, as told to by your doctor or nurse, even if your child does not have any wheeze or symptoms of asthma.

If your child’s asthma does not seem to be getting any better or they still need to use their reliever medicine often, contact your doctor or asthma nurse.

What if my child is sick (vomits)?

If your child is sick less than 30 minutes after having a dose of Zafirlukast, give them the same dose again.

If your child is sick more than 30 minutes after having a dose of Zafirlukast, you do not need to give them another dose. Wait until the next normal dose.

What if I forget to give it?

If you remember up to 4 hours after you should have given a dose, give your child the missed dose. For example, if you usually give a dose at about 7 am, you can give the missed dose at any time up to 11 am. If you remember after that time, do not give the missed dose. Wait until the next normal dose.

Never give a double dose of Zafirlukast.

What if I give too much?

You are unlikely to do harm if you give an extra dose of zafirlukast by mistake.

If you think you may have given your child too much zafirlukast, contact your doctor or NHS Direct (111 in England and Scotland; 111 or 0845 4647 in parts of Wales). 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).

Side effects you must do something about

If your child is more short of breath or is wheezing more than usual, or their face, lips or tongue start to swell, or they develop a rash, they may be allergic to Zafirlukast. Take your child to hospital or call an ambulance straight away.

Other side-effects you need to know about

The following side-effects should get better after a week. If they don’t, or you are worried, contact your doctor:

  • Your child may get stomach ache or stomach cramps or feel sick (nausea) or be sick (vomit). Giving the medicine with some food or milk may help.

  • Your child may get a headache (they may say their head is painful or pounding).

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 Zafirlukast?

  • You can give your child medicines that contain paracetamol or ibuprofen, unless your doctor has told you not to.
  • 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?

If your child has also been prescribed a steroid inhaler, it is important that they continue to use this as your doctor has told you to, while taking zafirlukast.

General advice about medicines

  • Try to give medicines at about the same times each day, to help you remember.
  • 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.
  • 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.
  • 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 think someone else may have taken the medicine by accident, contact your doctor straight away.

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 child’s doctor, pharmacist or nurse will be able to give you more information about Zafirlukast and about other medicines used to manage asthma.

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)

Asthma UK

0300 222 5800

Copyright disclaimer

Version [1]. © NPPG, RCPCH and WellChild, all rights reserved. Review by November 2015.

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.