Leukotriene Pathway Modifiers for Long-Term Control of Asthma

Example(s): Singulair (montelukast),Accolate (zafirlukast),Zyflo (zileuton)

Leukotriene Pathway Modifiers for Long-Term Control of Asthma


Generic Name Brand Name
montelukast Singulair
zafirlukast Accolate
zileuton Zyflo

These medicines are available as pills and chewable

How It Works

Leukotriene pathway modifiers improve
lung function and reduce
asthma symptoms.

Why It Is Used

The U.S. National Asthma
Education and Prevention Program (NAEPP) recommends leukotriene pathway
modifiers as an alternative treatment for people who have mild or persistent asthma.
Preferred medicines are inhaled corticosteroids with or without long-acting
beta2-agonists.footnote 1

These medicines may be used along with
corticosteroids to control
mild persistent and moderate persistent asthma. They
may be especially helpful for people whose asthma is triggered by exercise,
aspirin, or allergies.

Different types of medicines are often
used together in the treatment of asthma. Treatment for asthma
depends on a person's age, his or her type of asthma, and how well the
treatment is controlling asthma symptoms.

  • Children up to age 4 are usually treated a
    little differently than those 5 to 11 years old.
  • The least amount
    of medicine that controls the asthma symptoms is used.
  • The amount
    of medicine and number of medicines are increased in steps. So if asthma is not
    controlled at a low dose of one controller medicine, the dose may be increased.
    Or another medicine may be added.
  • If the asthma has been under
    control for several months at a certain dose of medicine, the dose may be
    reduced. This can help find the least amount of medicine that will control the
  • Quick-relief medicine is used to treat asthma attacks. But
    if you or your child needs to use quick-relief medicine a lot, the amount and
    number of controller medicines may be changed.

Your doctor will work with you to help find the number and
dose of medicines that work best.

How Well It Works

Research shows that compared
with a
placebo, leukotriene pathway modifiers:

  • Reduced symptoms in adults.footnote 2
  • Improved lung function in children. There are
    conflicting reports on whether they improved symptoms.footnote 3

But leukotriene pathway modifiers do not work as well
as inhaled corticosteroids. And adding leukotrienes to inhaled corticosteroids
is probably not as effective as adding long-acting beta2-agonists to inhaled
corticosteroids.footnote 2, footnote 3

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Common side effects of this medicine include:

  • Vomiting and diarrhea.
  • Headaches.

Leukotriene pathway modifiers can cause more serious problems such as mood changes, depression, hallucinations, and suicidal thinking. But this is rare.

In rare cases, zafirlukast and zileuton cause
liver damage. If the liver is being affected by zafirlukast or zileuton, liver
function tests
will show increased liver enzyme levels in the blood, usually
within the first 2 months of treatment.

Montelukast causes fewer
side effects than other leukotriene pathway modifiers. It is less likely to
affect the liver. So liver function monitoring is not needed.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

People who take
zafirlukast and medicine (called a blood thinner) that prevents blood clots need to
have their clotting times checked regularly. When used with blood-thinning
medicine, zafirlukast can increase the risk of bleeding. Zafirlukast also may
cause problems when taken with other medicines, such as blood pressure
medicines, aspirin, and some seizure medicines. Before you take zafirlukast, make sure your doctor knows
that you are taking any of those medicines.

People who are taking zafirlukast or
zileuton need to have liver function tests several times during the first 6
months of treatment. People who are taking theophylline along with zileuton may
need to take less theophylline.

People who take leukotriene
pathway modifiers may be more likely to take their medicine regularly, because
it can be taken orally and has a more immediate effect on symptoms than some
other medicines such as inhaled corticosteroids.

pathway modifiers are not used to treat
asthma attacks.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breastfeeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breastfeeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF) ( What is a PDF document? ) to help you understand this medication.



  1. National Institutes of Health (2007). National Asthma Education and Prevention Program Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma (NIH Publication No. 08–5846). Available online: ://www.nhlbi.nih.gov/guidelines/asthma/index.htm.
  2. Dennis RJ, Solarte I (2011). Asthma in adults (chronic), search date April 2010. BMJ Clinical Evidence. Available online: ://www.clinicalevidence.com.
  3. Turner ST, et al. (2012). Asthma and other recurrent wheezing disorders in children (chronic), search date June 2010. BMJ Clinical Evidence. Available online: ://www.clinicalevidence.com.


ByHealthwise StaffPrimary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine Adam Husney, MD - Family Medicine Specialist Medical Reviewer Elizabeth T. Russo, MD - Internal Medicine

Current as ofDecember 6, 2017