Leukotrine receptor antagonists (LTRAs)

You may have been prescribed a medicine called Leukotriene Receptor Antagonists (LTRAs).

LTRAs in brief

  • Some people with asthma are prescribed leukotriene receptor antagonists (LTRAs) as an 'add on' treatment by their GP, asthma nurse or hospital doctor. LTRAs are sometimes called preventer tablets. They are not steroids.
  • LTRAs relax the airways in your lungs to make breathing easier and to help prevent asthma attacks. They also reduce your body's response to allergens (substances that cause you to have an allergic reaction) and to certain situations which trigger asthma attacks (for example, exercise).
  • To get all the benefits, take LTRAs exactly as they're prescribed, usually once or twice a day.
  • It can take one or two weeks before you feel the full benefits of LTRAs. If they've had no effect after six weeks, they're probably not the right medicine for you.
  • Your LTRAs will not help during an asthma attack. Keep your fast-acting reliever inhaler with you at all times so you can use it if you have any asthma symptoms, such as coughing, wheezing, shortness of breath and tightness in the chest.

How do LTRAs help with asthma?

LTRAs relax the airways in your lungs to make breathing easier and to help prevent asthma attacks. They also reduce your body's response to allergens (a substance that causes you to have an allergic reaction) and to certain situations which trigger asthma attacks (for example, exercise).

LTRAs are sometimes called preventer tablets. They are not steroids.

The most common type is Montelukast (sometimes called by the brand name Singulair). Occasionally people with asthma are prescribed Zafirlukast (sometimes called by the brand name Accolate).

LTRAs are an 'add-on' to your usual medicine anddo not take the place of any other treatment you're taking. If you find that your asthma improves after you start taking this medicine, it is important that you don't stop taking any of your other medicines, as this will cause your symptoms to get worse again.

Who might get benefits from LTRAs?

If you've been taking inhaled steroids and your asthma still isn't well managed, your GP or asthma nurse will talk to you about the things that trigger your symptoms and may prescribe LTRAs to use alongside your inhaled steroids.

Children under five years who are unable to take inhaled steroid medicines, may be prescribed LTRAs to help prevent asthma symptoms.

LTRAs are sometimes prescribed for people with exercise-induced asthma.

If you have hay fever as well as asthma, your GP or asthma nurse may prescribe you LTRAs.

Is there anyone who shouldn't take LTRAs?

LTRAs are not suitable for everyone, including people with certain health conditions or people who are taking some medicines. It is very important that the person prescribing you medicines to help manage your asthma knows your full medical history.

How do LTRAs work?

LTRAs block the effects of chemicals in your body called 'leukotrienes'. Your body releases these chemicals during an allergic reaction and they cause your airways to become inflamed. Blocking the effects of these chemicals stops the inflammation and swelling. This in turn can improve your asthma symptoms and reduce the risk of a potentially fatal asthma attack.

LTRAs have been shown to reduce airway sensitivity to cold air, which is why they're sometimes prescribed as an add-on therapy for people with exercise-induced asthma.

LTRAs will not be useful during an asthma attack. Make sure you keep your fast-acting reliever inhaler with you at all times so you can use it if you have an asthma attack.

How often do you need to take LTRAs?

You usually take LTRAs once or twice a day. Your GP or asthma nurse will tell you how often you need to take them and write it on your written asthma action plan. This information is also written on the prescription label on the box of your medicine. If you're unsure, make an appointment to see your GP as soon as possible so you can ask. You can also ask your pharmacist.

It is very important that you take this medicine exactly as its prescribed. If you don't, you may not be getting all its benefits.

What kind of benefits can you expect?

Research shows that LTRAs can significantly reduce asthma symptoms both during the day and at night, helping to lower the risk of a potentially fatal asthma attack. In one 12-week trial of patients aged two to five, those taking it had more days without any asthma symptoms and needed lower doses of inhaled steroids. In another clinical trial carried out in adults, LTRAs reduced symptoms and lowered the need for higher doses of inhaled steroids.

In people with exercise-induced asthma, LRTAs have been shown to improve lung function, reduce symptoms, and reduce the use of reliever medicine. This medicine has also been shown to increase physical activity and improve quality of life.

Bear in mind, though, that it can take one or two weeks before you feel the full benefits of this medicine. But if LTRAs have had no effect after you've been taking them for six weeks, then they are probably not the right medicine for you. You and your GP or asthma nurse will need to discuss other treatment options.

The key things you need to know:

  • Over time, it is possible that LTRAs can become unsuitable for some people even if they have been suitable in the past. If you think that taking this medicine is causing you to become unwell, speak to your GP or asthma nurse straight away. They may be able to change the dose or way you take it (so you take the granules instead of a tablet, for example). Or they may need to change your prescription.
  • If you suddenly stop taking LTRAs, your asthma symptoms may return, which could lead to a potentially fatal asthma attack. If you're having any problems, it's important to speak to your GP or asthma nurse.
  • Tell your GP or asthma nurse if you are pregnant, planning to get pregnant or breast feeding as LTRAs may not be suitable for you.
  • In very rare cases, this medicine might affect your ability to drive or operate machinery. You should see how it affects you before you judge whether you are safe to drive or operate machinery. If you're in any doubt, talk to your GP, asthma nurse or pharmacist.

Possible side effects of LTRAs

Like all medicines, LTRAs can cause side effects. The important thing to remember is that a medicine is only ever available if clinical trials have shown that the benefits of taking it outweigh the risks. And although there's a long list of potential side effects, which can seem worrying when you read through it, everyone who takes LTRAs will respond to them differently. You may get some. You may get none.

The most common side effect of LTRAs is frequent sore throats and infections. More than one in ten people who take them will experience this. If you do, speak to your GP or asthma nurse.

Important: if you're taking LTRAs and you get any of the following symptoms, you should let your GP know straight away:

  • Continually feeling or being sick, jaundice (yellowing of your skin or the whites of your eyes), and generally feeling unwell. These can be signs of a liver problem and your GP will want to check for this.
  • Flu-like symptoms, numbness in your arms or legs, difficulties breathing, and a skin rash. These may be a sign of a rare but serious disorder called Churg-Strauss syndrome.

Other potential side effects include:

  • diarrhoea
  • fever
  • headaches
  • nausea
  • skin rash or rashes
  • stomach pain

For children who take LTRAs, side effects can also include:

  • vomiting
  • irritability
  • nightmares

If you or your child does get any side effects, or you're worried about anything at all, speak to your GP, asthma nurse or pharmacist as soon as possible. You may find that there are some simple things you can do to help prevent or reduce these side effects. We also have a useful Q&A about the common concerns you might have about taking asthma medicines here.

Get the best from your LTRAs

It is very important that you take LTRAs exactly as they're prescribed. If you don't, you may not be getting all the benefits. Here's how to get the best out of this medicine:

  • Get into a good routine so that you don't forget to take it at the right time(s) every day. You can try linking it to a habit - for example, if you need to take it twice a day you can keep it next to your toothbrush and take it when you clean your teeth in the morning and before bed. Or if you need to take it once a day in the evening, take it when you're putting on your pyjamas, for example. You might also find it helpful to set a reminder in your phone or make a note in your diary or on your calendar.
  • Montelukast is available as tablets to swallow with water, chewable tablets and granules to mix with water. This medicine must be taken every evening, after food. 
  • Zafirlukast comes as tablets. You should take these 'on an empty stomach', which means you need to take them about an hour before a meal, or wait for two hours after eating. This is because your body absorbs less Zafirlukast after a meal, which means the medicine is less effective.
  • If you forget to take a dose, take it as soon as you remember (unless it is nearly time for your next dose, in which case leave out the missed dose). Do not take two doses together to make up for a forgotten dose.
  • Book an annual asthma review (or every six months for children) with your GP or asthma nurse so they can check how you're doing.

Last updated May 2016

Next review due May 2019