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  1. About carbocisteine
  2. Key facts
  3. Who can and cannot take carbocisteine
  4. How and when to take it
  5. Side effects
  6. How to cope with side effects
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions

1. About carbocisteine

Carbocisteine is a type of medicine called a mucolytic.

A mucolytic helps you cough up phlegm (also called mucus or sputum). It works by making your phlegm less thick and sticky.

This can help if you have a condition that affects your lungs, including:

Carbocisteine is available on prescription only.

It comes as capsules and as a syrup or a liquid that you drink.

2. Key facts

  • Carbocisteine can be taken by adults and children from the age of 2 years.
  • You usually take this medicine 3 or 4 times a day.
  • You can take it with or without food.
  • Most people have no side effects when taking this medicine.
  • Carbocisteine is known by the brand name Mucodyne.

3. Who can and cannot take carbocisteine

Carbocisteine can be taken by adults and by children aged 2 years and older.

Carbocisteine is not suitable for some people. Tell your doctor before taking this medicine if you:

  • have had an allergic reaction to carbocisteine or any other medicines in the past
  • have a stomach ulcer, or you've had stomach ulcers before
  • are pregnant, planning to get pregnant, or are breastfeeding

4. How and when to take it

Carbocisteine usually comes as capsules.

It also comes as a liquid and as a syrup for children and people who find it difficult to swallow pills.

The liquid comes in individual sachets containing one dose. This is for adults and for children aged 15 and older.

The syrup comes with a plastic syringe or spoon to help you measure out the right dose. Do not use a kitchen spoon as this will not give you the correct amount.

You can take carbocisteine with or without food.

Dosage for adults

Capsules: two 375mg capsules, taken 3 times a day. When your symptoms improve, your doctor may recommend one 375mg capsule, taken 4 times a day.

Syrup: 15ml, taken 3 times a day. When your symptoms improve, your doctor may recommend 10ml, taken 3 times a day.

Liquid: 1 sachet, taken 3 times a day, reduced when symptoms improve to 1 sachet taken twice a day.

Dosage for children

2 to 4 years: 1.25ml to 2.5ml of syrup, given 4 times a day

5 to 11 years: 5ml of syrup, given 3 times a day

12 to 17 years: 15ml of syrup, given 3 times a day

What if I forget to take it?

If you forget a dose, take it as soon as you remember. If your next dose is due in less than 2 hours, skip the missed dose and take your next one as normal.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you forget doses often, it may help to set an alarm to remind you. You could also ask a pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Taking too much carbocisteine is unlikely to harm you or your child. In most cases you will not have any symptoms.

Immediate action required: Call 999 or go to A&E now if:

You take too much carbocisteine and you:

  • have an upset stomach
  • are vomiting

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the carbocisteine packet, or the leaflet inside it, plus any remaining medicine with you.

5. Side effects

Like all medicines, carbocisteine can cause side effects, although not everyone gets them.

Common side effects

If you're taking carbocisteine capsules or liquid you're unlikely to have side effects.

However, with the carbocisteine sachets, common side effects can happen to 1 in 10 people. Tell your doctor if these bother you or do not go away:

  • diarrhoea
  • feeling or being sick

Serious side effects

Serious side effects are rare.

Urgent advice: Contact 111 for advice now if:

  • you have blood in your vomit
  • your poo is black and tarry

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to carbocisteine.

Immediate action required: Call 999 or go to A&E now if:
  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of carbocisteine. For a full list see the leaflet inside your medicine packet.


You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects

What to do about:

  • diarrhoea – drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor. If this continues, speak to your doctor. They may recommend taking syrup or capsules instead of sachets.
  • feeling or being sick – stick to simple meals and do not eat rich or spicy food. It might help to take your medicine after you've eaten. If you're being sick, try small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. If this continues, speak to your doctor. They may recommend taking syrup or capsules instead of sachets.

If you are still being sick after more than a few days, or if your vomit contains blood, stop taking the medicine and see your doctor.

7. Pregnancy and breastfeeding

Carbocisteine is not generally recommended when pregnant. This is because there is very little information to say whether it is safe. Depending on why you need a mucolytic, your doctor might recommend an alternative medicine.

Carbocisteine and breastfeeding

It is generally OK to take carbocisteine while breastfeeding, as the amount that passes into breast milk is unlikely to harm your baby.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

8. Cautions with other medicines

Carbocisteine does not mix well with some medicines.

Tell your doctor or a pharmacist it you're taking any medicines that can cause bleeding or ulcers in your stomach. These include:

Mixing carbocisteine with herbal medicines

There is very little information about taking carbocisteine with herbal remedies and vitamin or mineral supplements. Not enough research has been done to say whether it is safe.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions

How does it work?

Carbocisteine works by making phlegm (mucus) less sticky. This makes it easier for you to cough up.

If you have a condition such as chronic obstructive pulmonary disease (COPD) or cystic fibrosis, your body can make too much phlegm and it can be thick and sticky.

Taking carbocisteine can ease some of your symptoms by making it easier to cough up any phlegm.

How long does it take to work?

It may take up to 4 weeks before you notice your symptoms improving. It can take time for the medicine to work and for phlegm to break up.

Keep taking your medicine even if you do not notice any improvement straightaway.

How long will I take it for?

Usually, treatment with carbocisteine is for life.

However, your doctor may stop you taking it if carbocisteine does not seem to be helping your symptoms after a month or so.

Is it safe to take long term?

There is no evidence to suggest that carbocisteine is harmful, even if you take it for a long time.

Are there similar medicines to carbocisteine?

There are a few other medicines that are prescribed for lung problems.

Erdosteine – this is an oral mucolytic medicine that works in a similar way to carbocisteine. It is usually prescribed for a short time if your chronic bronchitis is getting worse.

Dornase alfa and mannitol – these medicines are prescribed only for cystic fibrosis. You take them using an inhaler or nebuliser.

Can I drink alcohol with it?

Yes, you can drink alcohol while taking carbocisteine.

Are there foods and drinks I need to avoid?

You can eat and drink normally while taking carbocisteine.

Will it affect my contraception?

Carbocisteine does not affect any type of contraception, including the combined pill and emergency contraception.

However, if taking carbocisteine sachets makes you vomit or have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Read more about what to do if you're on the pill and you're being sick or have diarrhoea.

Will it affect my fertility?

There is no firm evidence that carbocisteine affects male or female fertility.

Can I drive or ride a bike?

Yes, you can drive or ride a bike while taking carbocisteine.

Page last reviewed: 6 January 2020
Next review due: 6 January 2023