An inhaled enzyme that thins lung mucus
Dornase alfa
An inhaled (nebulised) enzyme that thins sticky lung mucus in cystic fibrosis so it can be cleared more easily.
What is Dornase alfa?
Dornase alfa is a medicine you breathe in using a nebuliser to thin the thick, sticky mucus in the lungs of people with cystic fibrosis. It is an enzyme that breaks down material in the mucus, making it less sticky so it clears more easily and helping protect lung function. Common effects include a change in your voice and a sore throat, which are usually mild. It should not be mixed with other nebuliser solutions in the same chamber. It is part of specialist cystic fibrosis care, used alongside physiotherapy.
Education and reference only. This is a plain-language guide to Dornase alfa — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Dornase alfa is a mucolytic, a medicine that thins mucus, used in cystic fibrosis. Cystic fibrosis is a lifelong inherited condition in which the lungs fill with thick, sticky mucus that is hard to clear and tends to trap infection. Dornase alfa is an enzyme, given as a liquid that you breathe in through a nebuliser, which breaks down DNA released from cells inside the mucus, making it runnier. It is used regularly as part of a cystic fibrosis team's care plan.
How it works
Thick mucus in cystic fibrosis lungs contains a lot of sticky material, including DNA from dead inflammatory cells, which makes it stringy and hard to shift. Dornase alfa is an enzyme that breaks down this DNA, so the mucus becomes thinner and less sticky. Breathing it in as a fine mist through a nebuliser delivers it straight to the airways. With the mucus easier to clear, especially when combined with physiotherapy, lung function can improve and chest infections may become less frequent.
Company & origin
Originated / developed by: Roche.
A nebulised mucus-thinning medicine used in the UK to help people with cystic fibrosis clear sticky lung secretions.
Practical use
How to take Dornase alfa
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Breathe it in through your nebuliser as directed, usually once a day, using the device your team has set up.
- Do not mix it with other medicines in the same nebuliser chamber; take your nebulised treatments separately in the order your team advises.
- Follow it with your airway-clearance physiotherapy so the loosened mucus can be cleared.
- Clean and look after your nebuliser equipment exactly as instructed to keep it working safely.
- Store it as advised, often in the fridge and away from light, and check the appearance before use.
- Tell your team if your voice change, sore throat or breathing symptoms become troublesome.
Weighing it up
Advantages & disadvantages of Dornase alfa
Advantages
- Thins sticky lung mucus so it is easier to clear, which can improve breathing.
- Can help reduce chest infections and protect lung function over time.
- Delivered straight to the lungs by nebuliser, with few effects on the rest of the body.
Disadvantages
- Needs daily nebuliser treatment and time for cleaning the equipment.
- Can cause voice changes, a sore throat and sometimes a temporary dip in breathing.
- Must not be mixed with other nebuliser solutions, so treatments have to be spaced and ordered carefully.
Practical use
Good to know
Dornase alfa is breathed in through a nebuliser, usually once a day, and works best when followed by your airway-clearance physiotherapy so the loosened mucus can be moved out. A key practical point is that it should not be mixed with, or diluted by, other medicines in the same nebuliser chamber, as this can stop it working — your team will tell you the order to take your nebulised treatments. Common effects are a change in your voice (it may sound hoarse), a sore throat, and sometimes a temporary dip in breathing; these are usually mild. The nebuliser equipment needs cleaning as instructed to keep it safe and effective. It is part of specialist cystic fibrosis care and does not replace your other treatments.
Who should not take it / use with caution
- Anyone who has had a serious allergic reaction to dornase alfa.
- It is used with care, and the response checked, in people whose breathing worsens after using it.
- It should not be mixed with other medicines in the nebuliser, as this can make it ineffective.
Monitoring
- Reviewing lung function and how easily mucus is being cleared.
- Checking for voice changes, sore throat or any worsening of breathing.
- Making sure nebuliser technique and equipment cleaning are being kept up.
Side effects
- Voice changes (hoarseness) and a sore throat are among the most common effects.
- A temporary dip in lung function or chest discomfort in some people.
- Less commonly, sore eyes, a rash or a raised temperature.
Key interactions
- It must not be mixed or diluted with other medicines in the same nebuliser chamber, as this can stop it working.
- No major interactions with tablets are expected, but tell your team about all your treatments.
- Your team will advise on the order of your nebulised medicines and physiotherapy.
Available as: A solution breathed in (nebulised) through a nebuliser.
Answers
Dornase alfa: frequently asked questions
How does dornase alfa help my chest?
It is an enzyme that breaks down material in sticky mucus, making it thinner so it clears more easily and helping protect your lungs.
Can I mix it with my other nebuliser medicines?
No, it must not be mixed with other medicines in the same chamber; take your nebulised treatments separately in the order your team advises.
Why has my voice changed?
A hoarse voice and sore throat are common with this medicine and are usually mild; tell your team if they become troublesome.
When should I do my physiotherapy?
It usually works best to follow the medicine with your airway-clearance physiotherapy, so the loosened mucus can be moved out.
Does it replace my other cystic fibrosis treatments?
No, it is part of your overall care and should be used alongside your other treatments, not instead of them.
Authoritative sources
- BNF
- NICE CKS
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