The Use of Singulair (Montelukast) for Allergies

Singulair (montelukast) is an an oral medicine that is often prescribed for asthma and may also be used to treat allergies, or allergic rhinitis. Singulair treats allergy symptoms like sneezing, coughing, nasal congestion, and itchiness by blocking leukotrienes—chemicals in your body that cause inflammation.

Singulair may cause side effects, including rash, headache, stomach pain, diarrhea, ear infection, and others. The risk of mental health concerns the drug poses make Singulair an option that is typically only prescribed after other allergy treatments have failed.

This article takes a closer look at Singulair, including its uses and side effects. It also covers how it works differently than medicines typically used to treat allergic rhinitis.

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Singulair has a boxed warning from the U.S. Food and Drug Administration (FDA) due to potential

mental health side effects, including suicidal thoughts or actions.

If you or someone you know are having suicidal thoughts, dial 988 to contact the 988 Suicide & Crisis Lifeline and connect with a trained counselor. For more mental health resources, see our National Helpline Database.

Singulair Uses

Singulair is prescribed to prevent symptoms of chronic asthma. In some people, the drug might even prevent exercise-induced asthma.

It is also used to treat allergic rhinitis (allergies). There are two main types of allergic rhinitis:

  • Seasonal allergic rhinitis. Pollen from trees, grasses, and weeds can trigger seasonal allergic rhinitis. Seasonal allergies are typically highest in the spring and summer when pollen levels are high. Symptoms can occur in the fall, especially for people who are allergic to weed pollen.
  • Perennial allergic rhinitis. This form of allergic rhinitis causes symptoms all year. Common triggers are indoor allergens, dust mites, cockroaches, mold, or animal dander.

Off-Label Uses of Singulair

Off-label use of a prescription medicine means the Food and Drug Administration (FDA) hasn't approved the drug for that use, but it can still be an effective treatment.

Some health professionals use Singulair off-label to treat chronic urticaria (recurrent hives) or atopic dermatitis.

What to Know Before Using Singulair

Symptoms of allergic rhinitis include:

  • Sneezing
  • Runny nose
  • Nasal congestion
  • Itchy eyes, nose, throat, and inner ear
  • Feeling weak or tired
  • Cough

Allergic rhinitis can also affect other areas of your life. Research shows that allergic rhinitis negatively impacts:

  • Sleep
  • Quality of life
  • Concentration
  • Productivity at school or work

You can control allergic rhinitis by avoiding allergens and taking medicine. If you choose to take medicine, your healthcare professional may recommend a step-up approach. That means that you'll start with a medication that has a low risk of side effects. If that doesn't work or symptoms get worse, your healthcare professional might prescribe a different drug.

Here's an example of treatments that might be recommended:

If you've tried other treatments for allergic rhinitis and they don't work, your healthcare provider may prescribe Singulair. But it's usually not the first-line treatment.

How Singulair Works

Cells in your body react to allergens by making a chemical called histamine. This chemical is involved in the body's immune response, and it triggers the symptoms known as allergies.

Many of the medications that are commonly used to treat allergic rhinitis are antihistamines. These drugs block the effects of histamine. Popular antihistamines include Claritin or Allegra.

Singulair isn't an antihistamine. Instead, Singulair blocks leukotrienes, which are another type of chemical involved in the inflammation associated with allergic rhinitis and asthma.

How Long Does It Take Singulair to Work?

Singulair is taken once a day. It may take several weeks before a significant improvement in breathing measurements, such as forced expiratory volume (FEV1) takes effect.

Taking certain types of medications with Singulair may decrease its effectiveness.

Dosage of Singulair For Allergies

The typical dosages of Singulair for allergies are:

  • Adult and adolescent patients 15 years of age and older: one 10 mg tablet once daily
  • Pediatric patients 6 to 14 years of age: one 5 mg chewable tablet once daily
  • Pediatric patients 2 to 5 years of age: one 4 mg chewable tablet or one packet of oral granules once daily

The safety of Singulair in babies 12 to 23 months of age has not been determined.

Side Effects of Singulair

Overall, Singular is a safe medicine, but side effects may occur.

Some common side effects include: 

  • Skin rash
  • Mood changes
  • Headache or dizziness
  • Stomach pain
  • Heartburn or indigestion
  • Nausea, diarrhea, or constipation
  • Toothache or infection
  • Ear pain or infection
  • Muscle weakness
  • Conjunctivitis (pink eye)
  • Fatigue
  • Flu-like symptoms

Because of the risk of severe mental health side effects, talk to your healthcare professional if you take Singulair and experience any symptoms that worry you.

A rare side effect of Singulair is a severe allergic reaction to the drug. If you start to feel swelling in your throat or have difficulty breathing, get medical treatment right away.


Singulair is most commonly used to prevent asthma symptoms. While it isn't the first-line treatment for seasonal or year-round allergies, it is sometimes prescribed to treat them as well.

Keep in mind that the FDA has included a boxed warned for Singulair due to possible severe mental health side effects.

If you have allergies, know that Singulair isn't your only option. You can take antihistamines or nasal sprays before trying Singulair.

Frequently Asked Questions

  • Is Singulair an antihistamine?

    No. Singular blocks leukotrienes, not histamines. Leukotrienes cause allergy symptoms like coughing, inflammation in the airways, and trouble breathing.

  • Is Singulair usually recommended for seasonal allergies?

    No. The FDA recommends trying other medications before turning to Singulair (montelukast) for allergic rhinitis or mild asthma symptoms. It can increase the risk of agitation, depression, sleeping problems, and suicidal thoughts and actions. In 2020, Singulair added a black box warning label to call out these risks.

  • Can montelukast be used to treat COVID?

    Maybe. Some evidence shows that montelukast can help prevent people hospitalized with COVID-19 from developing more serious symptoms. But more research needs to be done.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.