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Mucus (sputum) is made in the lungs. Mucolytics are medicines that make the mucus less thick and sticky and easier to cough up. They are usually prescribed for people who have a long-term (chronic) cough. They work best if taken regularly.

Mucolytics are medicines that make mucus less thick and sticky and easier to cough up. They are helpful where there is a long-term (chronic) cough .

The term 'expectorant' is a general term used to describe a type of cough medicine which reduces the thickness or stickiness of mucus so it can be removed from the lung more easily by coughing.

Mucolytics work by breaking down the structure of the molecules that form the mucus.

There are a number of mucolytics available to prescribe in the UK. These include carbocisteine and erdosteine. Both are available as capsules. Carbocisteine is also available as an oral liquid.

Two other types of mucolytic are available to prescribe. They are called dornase alfa and mannitol. These medicines are inhaled but are usually only prescribed for people with cystic fibrosis.

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The mucus (sputum) in the lungs is held together by certain bonds. Mucolytics work by breaking these bonds. When these bonds are broken, the mucus becomes less sticky and less thick and is therefore easier to cough up. This may also result in making it harder for germs (bacteria) to infect the mucus and cause chest infections.

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They are normally prescribed for people with a long-term (chronic) productive cough. People with a productive cough make a lot of mucus (sputum) in their lungs . Examples of people who may have a chronic productive cough include people with chronic obstructive pulmonary disease (COPD) and people with cystic fibrosis.

They are most likely to help in people with moderate or severe COPD who have frequent or significant flare-ups (exacerbations). The number of flare-ups of symptoms tends to be less in people who take a mucolytic.

Dornase alfa is usually only prescribed for people with cystic fibrosis who have a reduced lung capacity. It helps to make it easier to cough up thick mucus and is thought to improve how well the lungs work. It also limits any further damage to the lungs. This medicine is usually started by a doctor who specialises in treating patients with cystic fibrosis. Mannitol is an alternative for people with cystic fibrosis who can't take dornase alpha.

Mucolytics work best when they are taken regularly.

Carbocisteine and erdosteine are usually taken twice a day (but up to four times a day) by adults. These medicines may be stopped if they have been taken for one month and don't seem to be helping symptoms. Children may need to take these medicines three or four times a day.

Dornase alfa is taken by breathing it directly into the lungs once or twice a day, using a machine called a nebuliser. Mannitol is taken by breathing it in from a hand-held inhaler.

Side-effects of treatment with mucolytics occur rarely but some people have reported bleeding from the gut (gastrointestinal tract). . Black tarry stools are a sign of bleeding from the gut - although this is a very rare side effect, people who develop this should stop their carbocisteine or erdosteine and seek medical advice

Most people are able to take a mucolytic; however, they should not be used in people who have a stomach ulcer.

No, they require a prescription.

Medical advice should be sought for a cough that has persisted without improving for more than three weeks. Treatment will depend on the cause.

Some people need help with a long-term cough for which no cause can be found. A steamy shower or steam from a humidifier can help to loosen phlegm. Simple linctus and cough sweets can be soothing.

Cough suppressant medicines may help, especially for a night-time cough, but these usually contain codeine which can cause constipation if taken excessively.

For more information, see the separate leaflet called Chronic Persistent Cough in Adults.

How to use the Yellow Card Scheme

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • The person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.

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