A tablet to help prevent asthma symptoms
Zileuton
A tablet used to help prevent asthma symptoms, used mainly outside the UK.
What is Zileuton?
Zileuton is a tablet used to help prevent asthma symptoms over the long term. It is a 5-lipoxygenase inhibitor, which lowers the levels of inflammatory chemicals called leukotrienes that narrow the airways. It is a preventer and does NOT treat a sudden asthma attack, for which a reliever inhaler is needed. Its most important risk is liver injury, so liver blood tests are checked regularly. It can also affect mood and behaviour. It is mainly a United States product and is not a usual UK medicine.
Education and reference only. This is a plain-language guide to Zileuton — 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
Zileuton is a medicine used to help prevent asthma symptoms. It works on the leukotriene pathway, which is involved in airway inflammation, by blocking an enzyme called 5-lipoxygenase. It is taken as a tablet by mouth. It is a preventer, taken regularly to keep asthma under control, and is not a treatment for a sudden asthma attack. It is mainly used in the United States and is not a standard UK medicine, where other preventers, including inhaled steroids and other leukotriene medicines, are normally used instead.
How it works
In asthma, the airways become inflamed and narrowed, partly because of chemicals called leukotrienes, which are made by an enzyme called 5-lipoxygenase. Zileuton blocks this enzyme, so fewer leukotrienes are produced, which reduces airway inflammation and helps keep the airways open over time. Because it works gradually to keep inflammation down, it is taken regularly as a preventer rather than for quick relief, and it does not open the airways fast enough to treat a sudden asthma attack.
Company & origin
Originated / developed by: Various manufacturers.
An asthma-prevention tablet used mainly in the United States; it is not a usual UK product.
What it treats
Conditions Zileuton is used for
Practical use
How to take Zileuton
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it regularly as prescribed to prevent asthma symptoms, not just when you feel wheezy.
- Keep using your fast-acting reliever inhaler for sudden symptoms, as this tablet does not treat an asthma attack.
- Attend your liver blood test appointments, which are needed regularly because it can affect the liver.
- Report promptly any yellowing of the skin or eyes, dark urine, severe tiredness or tummy pain, which may signal liver problems.
- Tell your prescriber about any new low mood, agitation, sleep problems or unusual thoughts.
Weighing it up
Advantages & disadvantages of Zileuton
Advantages
- Helps prevent asthma symptoms by reducing airway inflammation.
- Taken as a tablet, which some people prefer to inhalers.
- Works on the leukotriene pathway, offering a non-steroid preventer option.
Disadvantages
- Does not treat a sudden asthma attack, so a reliever inhaler is still essential.
- Can cause liver injury, so regular liver blood tests are needed.
- Can affect mood and behaviour, and is mainly a United States product not usually used in the UK.
Practical use
Good to know
Two things matter most with zileuton. First, it is a preventer, not a reliever: it does not treat a sudden asthma attack, so you must keep and use a fast-acting reliever inhaler for that and seek urgent help if your breathing suddenly worsens. Second, it can affect the liver, sometimes seriously, so regular liver blood tests are done, usually more often at the start of treatment, and any yellowing of the skin or eyes, dark urine, severe tiredness or tummy pain should be reported promptly. It can also affect mood and behaviour, so any new low mood, agitation, sleep problems or unusual thoughts should be reported. It is mainly a United States medicine and is not a usual UK choice, where other asthma preventers are normally used.
Who should not take it / use with caution
- People who have had a serious allergic reaction to zileuton should not take it.
- It is not used in people with active liver disease or with raised liver enzymes on blood tests.
- It is used with care in people with a history of mental-health problems, because it can affect mood.
- It is used with caution alongside heavy alcohol use, which also affects the liver.
Monitoring
- Regular liver blood tests, more often when treatment first starts.
- Reviewing how well asthma is controlled and how often the reliever inhaler is needed.
- Watching for mood or behaviour changes and signs of liver problems.
Side effects
- Changes in liver blood tests, and rarely serious liver injury.
- Headache, tummy pain, nausea or muscle aches.
- Mood or behaviour changes, such as low mood, agitation, sleep problems or unusual thoughts.
- Rarely but seriously, signs of liver damage such as yellowing of the skin or eyes, which need urgent attention.
Key interactions
- It can raise the levels of some other medicines, such as the blood thinner warfarin and the asthma medicine theophylline, so doses may need adjusting.
- Alcohol and other medicines that affect the liver add to the risk of liver problems.
- Tell your prescriber about all your medicines, as zileuton can change how some of them work.
Available as: Tablets taken by mouth.
Answers
Zileuton: frequently asked questions
What is zileuton used for?
It is a tablet used to help prevent asthma symptoms by lowering inflammatory chemicals called leukotrienes that narrow the airways.
Can it treat an asthma attack?
No. Zileuton is a preventer; it does not treat a sudden asthma attack, so you must keep and use a fast-acting reliever inhaler and seek urgent help if your breathing worsens.
Why do I need liver blood tests?
Zileuton can affect the liver, sometimes seriously, so liver blood tests are done regularly, usually more often at the start, to catch any problems early.
Can it affect my mood?
It can cause mood or behaviour changes, such as low mood, agitation or sleep problems, so report any such changes to your prescriber promptly.
Is it used in the UK?
It is mainly a United States product and is not a usual UK medicine; in the UK other asthma preventers, including inhaled steroids and other leukotriene medicines, are normally used.
The wider class
About Leukotriene pathway medicine (5-lipoxygenase inhibitor)
Zileuton belongs to the leukotriene pathway medicine (5-lipoxygenase inhibitor) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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