Singulair

Written by Sarah Lewis, PharmD
Medically reviewed by Rosanna Sutherby, PharmD
Updated on June 28, 2023

The Food and Drug Administration (FDA) has approved montelukast sodium to:

• treat and prevent asthma in adults and certain children
• prevent exercise-induced bronchoconstriction (tightening of the lung’s airways) in adults and certain children
• treat allergies, such as hay fever, in adults and certain children

These approved uses differ based on the form of montelukast sodium your doctor prescribes.

This article describes montelukast sodium’s uses, side effects, and more. You’ll also find some coupon options to help save on the cost of montelukast sodium.

Boxed warning: Risk of serious behavior or mood changes

Montelukast sodium has a boxed warning about the risk of serious behavior or mood changes. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA).

For details, see the “Interactions and warnings for montelukast sodium” section.

Below you’ll find answers to a few commonly asked questions about montelukast sodium.

Is montelukast sodium similar to levocetirizine or fexofenadine?

No, montelukast sodium is different than levocetirizine or fexofenadine. Montelukast sodium belongs to a group of drugs called leukotriene receptor antagonists. Levocetirizine and fexofenadine are antihistamines.

Doctors may prescribe these drugs for similar purposes. All three drugs may be options for people who have allergies, such as hay fever. But only montelukast sodium is approved to treat lung conditions, such as asthma.

Talk with your doctor or pharmacist for more information.

How does montelukast sodium work? And how long does it take to start working?

Montelukast sodium binds to sites on cells called leukotriene receptors. These sites are found on cells in the airways and on cells involved in inflammation (swelling). By binding to these sites, the drug reduces inflammation. It also helps relax and open airways, including the nasal passages.

Montelukast sodium starts working within a few hours of taking the drug. It may take a few days for asthma and allergy symptoms to improve.

If you’d like to know more about this, talk with your doctor or pharmacist.

The Food and Drug Administration (FDA) approves prescription drugs such as montelukast sodium for certain conditions. Approved uses for montelukast sodium are described below. These uses differ based on the form your doctor prescribes.

Use for allergies

Doctors may prescribe montelukast sodium oral tablet, oral granule, or chewable tablet to treat allergies. It’s used for this purpose in adults and certain children. Doctors usually prescribe it as a long-term treatment.

The oral tablet treats allergies in adults and children 15 years and older. The oral granule and chewable tablet treat seasonal allergies in adults and children 2 years and older. Adults and children 6 months and older can use these forms for year-round allergies.

With allergies, your body’s immune system releases chemicals in response to allergens. Examples of allergens include:

• animal dander
• dust mites
• mold spores
• plant pollen

Leukotrienes are a type of chemical that play a role in allergies. They can cause cough, extra mucus, and swelling in the airways, including the nasal passages. Montelukast sodium helps relieve these symptoms.

Doctors may not prescribe montelukast sodium in certain situations, such as for people who haven’t tried other allergy treatments. Doctors usually prescribe this drug for allergies only when previous treatments haven’t helped.

Use for breathing problems

Doctors may prescribe montelukast sodium oral tablet, oral granule, or chewable tablet to treat or help prevent certain breathing problems. This includes asthma and exercise-induced bronchoconstriction (EIB), which is tightening of the lung’s airways. It helps treat breathing problems in adults and certain children. Doctors usually prescribe it as a long-term treatment.

Doctors may prescribe the oral tablet for breathing problems in adults and children 15 years and older. They may prescribe the oral granule and chewable tablet to treat and prevent asthma in adults and children 12 months and older. They may prescribe the chewable tablet to treat EIB in adults and children 6 years and older.

With asthma and EIB, leukotrienes play a role in swelling and tightening of the lung’s airways. This can cause difficulty breathing and other symptoms, such as wheezing. Montelukast sodium helps with these symptoms.

It’s important to know that montelukast sodium is not a rescue medication for asthma or EIB. Instead, it helps manage these conditions long term and prevent attacks.

Montelukast sodium may cause mild or serious side effects. The drug’s more common mild side effects and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about montelukast sodium’s side effects, ask your doctor or pharmacist. You can also refer to the drug’s prescribing information in the “Article resources” section.

Mild side effects

More common mild side effects reported with some forms of montelukast sodium are listed below.

This article doesn’t include all possible mild side effects of the drug. To learn more about montelukast sodium’s side effects, refer to the drug’s prescribing information in the “Article resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Montelukast sodium’s mild side effects include:

• belly pain
• cough
• diarrhea
• headache
• mild allergic reaction*

* For details about this side effect, see the “Interactions and warnings for montelukast sodium” section.

Serious side effects

Serious side effects of montelukast sodium are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about montelukast sodium’s side effects, refer to the drug’s prescribing information in the “Article resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, montelukast sodium’s serious side effects include:

• high eosinophil counts (a type of white blood cell), which can sometimes occur with inflamed blood vessels
• high liver enzyme levels, which can be a sign of liver problems
• low platelet levels*
• boxed warning: risk of serious behavior or mood changes†
• severe allergic reaction†

† This side effect wasn’t reported in montelukast studies, but people have reported it since the drug’s been available.
* For details about this side effect, see the “Interactions and warnings for montelukast sodium” section.

Suicide prevention

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

• Call the 988 Suicide and Crisis Lifeline at 988.
• Text HOME to the Crisis Textline at 741741.
• Not in the United States? Find a helpline in your country with Befrienders Worldwide.
• Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you are not in the same household, stay on the phone with them until help arrives.

Below, you’ll find information about montelukast sodium’s possible interactions and warnings.

Interactions of montelukast sodium

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take montelukast sodium, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for montelukast sodium” section below.

Warnings for montelukast sodium

Some people should not take montelukast sodium, and others should take it cautiously.

Boxed warning: Risk of serious behavior or mood changes

Montelukast sodium has a boxed warning about the risk of serious behavior or mood changes. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA).

With this risk, mental health problems can occur while taking montelukast sodium or after stopping it. This has happened in people of all ages and in those with and without mental health problems in the past.

Due to this risk, doctors will closely monitor you for symptoms of serious behavior or mood changes. They usually do not prescribe montelukast sodium for allergies unless other treatments haven’t worked.

Symptoms may include:

• hostile or aggressive behavior
• bad or vivid dreams
• depression
• hallucinations (seeing or hearing things that aren’t real)
• difficulty remembering things
• suicidal thoughts or actions

If you any of these symptoms, tell your doctor right away. They’ll likely recommend that you stop taking montelukast sodium immediately.

To learn more, talk with your doctor or pharmacist.

Other warnings

Montelukast sodium could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether montelukast sodium is a safe option for you.

Ask your doctor about specific warnings for montelukast sodium, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Montelukast sodium can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to montelukast sodium or any of its ingredients, your doctor will likely not prescribe montelukast sodium. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• severe skin rashes that may blister and peel
• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to montelukast sodium, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of montelukast sodium

You should not take more montelukast sodium than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much montelukast sodium, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and montelukast sodium

Information about montelukast sodium and pregnancy and breastfeeding is described below.

Montelukast sodium and pregnancy

In general, montelukast sodium is considered safe to take during pregnancy. That said, ask your doctor about whether they feel it’s safe for you.

Montelukast sodium and breastfeeding

In general, montelukast sodium is considered safe to take while breastfeeding. That said, ask your doctor about whether they feel it’s safe for you.

This article describes montelukast sodium’s uses and side effects, ways to save on cost, and more. Let your doctor know if you have questions about montelukast sodium or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• What’s the most important information to know about montelukast sodium?
• How should I take montelukast sodium?
• Is there anything I should avoid while taking montelukast sodium?

• Fexofenadine — fexofenadine tablet. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/d35a5ce4-cd83-5b1f-e053-2995a90a24db/spl-doc?hl=fexofenadine
• Levocetirizine dihydrochloride tablets, for oral use. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/1b593c65-2866-45d9-9c94-ac181f4cbc51/spl-doc?hl=levocetirizine
• Montelukast sodium oral granules for oral use. (2021). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/9a3bfc59-0ca6-4433-abf5-41659bfe0a8f/spl-doc
• Montelukast sodium chewable tablets, for oral use. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/c43d1edb-c162-4317-9a89-d84e4eff5512/spl-doc
• Montelukast sodium tablets, for oral use. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/fdc5e630-3a01-4db6-8107-0e220dca2ba1/spl-doc
• Orange Book: Approved drug products with therapeutic equivalence evaluations. (2023) https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.