Singulair (montelukast) is an an oral medicine that may 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 spur inflammation.

This can may particularly helpful to those who also have asthma, another indication for this drug. While not as effective as a steroid inhaler, Singulair can help reduce airway narrowing.

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.

Singulair Uses

Doctors can prescribe Singulair to prevent symptoms of chronic asthma. In some people, the drug might even prevent exercise-induced asthma.

Singulair can also relieve symptoms of allergic rhinitis.

There are two main types of allergic rhinitis: seasonal and perennial:

  • 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 causes symptoms all year. Common triggers are indoor allergens: dust mites, cockroaches, mold, or animal dander.

Off-Label Uses of Singulair

Doctors might prescribe Singulair for off-label use for some conditions. Off-label means the Food and Drug Administration (FDA) hasn’t approved the drug for that use, but it can still be an effective treatment.

For example, some people use Singulair off-label to treat chronic urticaria (recurrent hives) or hives caused by using non-steroidal anti-inflammatory drugs (NSAIDs).

What to Know Before Using Singulair

Symptoms of allergic rhinitis include:

  • SneezingRunny noseNasal congestionItchy eyes, nose, throat, and inner earFeeling weak or tiredCough

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

  • SleepQuality of lifeConcentrationProductivity at school or work

You can control allergic rhinitis by avoiding allergens or taking medicine. If you choose to take medicine, doctors often recommend a step-up approach. That means that you’ll start with less powerful medicine with a low risk of side effects. If that doesn’t work or symptoms get worse, your doctor might prescribe a different medicine.

Here’s an example of treatments that your doctor might recommend:

  • Antihistamines
  • Nasal steroid sprays
  • Both an antihistamine and nasal steroid

If you’ve tried other treatments for allergic rhinitis and they don’t work, your doctor might prescribe Singulair. But it’s usually not the first-line treatment. That’s because it might cause mental health side effects in some people, including suicidal thoughts and actions.

Due to these side effects, the FDA usually recommends using Singulair for allergic rhinitis only if other treatments don’t work. That said, some people respond well to Singulair, and it may be the most effective treatment for their allergies or asthma. 

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 of allergic rhinitis and asthma.

Side Effects off Singulair

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

Some common negative effects are: 

  • 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

Talk to your doctor 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.

Summary

Singulair can be used to prevent asthma symptoms. Some doctors might prescribe it to treat seasonal or year-round allergies. But it’s usually not the first choice because it can cause serious 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.

A Word From Verywell

Talk to your doctor about your treatment plan. Tell them if your symptoms aren’t getting better or if they affect your quality of life. There are many ways to treat allergies. Rest assured that you can find a therapy to help you feel better. But it may take some trial and error to find the best treatment for you. 

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.
  • Learn More:
  • What Is Allergic Asthma?
  • 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.
  • Learn More:
  • What You Should Know About a Black Box Warning
  • 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.
  • Learn More:
  • COVID-19 Treatments

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

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.

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.