Dornase alfa for cystic fibrosis

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

Dornase alfa (often referred to as DNase)

Brand names: Pulmozyme® 

This leaflet is about the use of dornase alfa for cystic fibrosis.

Why is it important for my child to take dornase alfa?

In cystic fibrosis, the mucus that lines the lungs is thicker than normal and is difficult to clear. Bacteria may become trapped in the mucus and cause infection. Dornase alfa helps to break down the thick mucus and will help your child’s lungs to work better.

What is dornase alfa available as?

Dornase alfa has to be inhaled into the lungs (breathed in). A special device called a jet nebuliser is used. The medicine comes in plastic ampoules containing 2.5 mL of solution (2.5 mg dornase alfa) for use in the nebuliser.

When should I give dornase alfa

Dornase alfa is usually given once each day, at least one hour before physiotherapy. Your child may only need to take dornase alfa every other day (alternate days).

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

How much should I give?

Your doctor will work out the amount of dornase alfa (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 dornase alfa?

Solution for use in a nebuliser

Your doctor, physiotherapist, specialist nurse or pharmacist will show you how to use the jet nebuliser. This machine makes the medicine into a mist that your child needs to breathe into their lungs. It is important that the medicine in the nebuliser is not mixed with other medicines, liquids or water. Always use dornase alfa exactly as your doctor has told you.

When should the medicine start working?

It usually takes about 2 weeks for dornase alfa to work but it may take 6–12 weeks if the mucus in your child’s lungs is very thick. Continue to give the medicine to your child during this time. Your doctor will decide whether it is helping once your child has been taking it for a few weeks. 

What if my child is sick (vomits)?

You do not need to worry if your child is sick, as the medicine will still work.

What if I forget to give it?

Give the missed dose when you remember during the day as long as this is at least 12 hours before the next dose is due.

What if I give too much?

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

If you are concerned that you may have given too much, contact your hospital 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 are rare with dornase alfa.

Side effects you must do something about

Rarely, dornase alfa can cause chest pain or increased difficulty with breathing. If these happen contact your doctor straight away.

Other side-effects you need to know about

Your child may get one of the following side-effects, but they are usually mild:

  • a stomach upset (indigestion)

  • fever (temperature above 38°C)

  • a sore throat or changes to their voice, such as hoarseness, or temporary voice loss

  • a skin rash or sore or irritated eyes (conjunctivitis)

Contact your doctor if you are worried, but continue to give dornase alfa.

Can other medicines be given at the same time as dornase alfa?

  • 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.

Your child should continue their regular medical care and chest physiotherapy while taking dornase alfa.

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

Your child may produce more mucus when they first start taking dornase alfa and so their breathing may be a little more difficult. However, this normally improves with time and the lungs will start to work better.

If dornase alfa does not seem to be helping your child’s breathing, contact your doctor for advice. Do not give extra doses of dornase alfa unless your doctor tells you to.

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?

  • Make sure that children cannot see or reach the medicine.
  • Keep the medicine in the container it came in.
  • Keep the medicine ampoules in a fridge in their original packaging to protect them from light. Do not use an ampoule that has been out of the fridge for more than 24 hours.

Who to contact for more information?

Your doctor, pharmacist or nurse will be able to give you more information about dornase alfa and about other medicines used to treat cystic fibrosis.

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)

Cystic Fibrosis Trust

Copyright disclaimer

Version [1]. © NPPG, RCPCH and WellChild, all rights reserved. Review by September 2013.

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.