Singulair (montelukast)

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Singulair® (montelukast) is a leukotriene modifier that may help to improve symptoms of asthma and inflammation of the lining of the nose (allergic rhinitis, or hay fever). Singulair is typically prescribed as add-on therapy when inhalers do not adequately control asthma. Singulair is used to:1

  • Prevent asthma attacks and for the long-term treatment of asthma in adults and children ages 12 months and older.
  • Prevent exercise-induced asthma in people ages 6 years and older.
  • Treat seasonal hay fever in people ages 2 years and older who have not responded to or cannot take other treatments.
  • Treat year-round hay fever in people ages 6 months and older who have not responded to or cannot take other treatments.

Singular should not be used to treat a sudden asthma attack. Use your rescue inhaler medicine for an asthma attack.1

Singulair is taken by mouth. It comes as tablets, chewable tablets, and oral granules.1

What are the ingredients in Singulair?

The active ingredient in Singulair is montelukast sodium.1

How does Singulair work?

Singulair works by blocking a chemical called leukotriene. Leukotriene plays a role in triggering asthma and hay fever symptoms, including:1

  • Inflammation and swelling in the lungs and airways
  • Narrowing of the airways
  • Swelling in the nasal passages
  • Increased mucus production and buildup

By blocking leukotriene, Singulair helps to prevent asthma and hay fever symptoms.1

What are the possible side effects?

The most common side effects of Singulair include:1

  • Upper respiratory tract infection
  • Fever
  • Headache
  • Sore throat
  • Cough
  • Stomach pain
  • Diarrhea
  • Earache or ear infection
  • Flu
  • Runny nose
  • Sinus infection

In rare cases, Singulair may also cause:1

  • Increase in certain white blood cells (eosinophils)
  • Possible inflamed blood vessels throughout the body (systemic vasculitis)

This may happen in people who also take a steroid medicine by mouth that is being stopped or the dose is being lowered. Tell your doctor right away if you have any of the following symptoms while taking Singulair:1

  • A feeling of pins and needles or numbness in arms or legs
  • A flu-like illness
  • Rash
  • Severe pain and swelling of the sinuses (sinusitis)

Singulair has a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). It has this warning because it may cause mood or behavior changes including:1

  • Agitation or irritability
  • Anxiety
  • Attention problems
  • Bad or vivid dreams
  • Seeing or hearing things that are not really there (hallucinations
  • Depression
  • Confusion
  • Memory problems
  • Sleep problems and sleepwalking
  • Stuttering
  • Tremor
  • Uncontrolled muscle movements
  • Thoughts or acts of self-harm

Because of these possible changes, the benefits of Singulair may not outweigh the risks for some people. Singulair should only be used by people with hay fever who have not responded to or cannot take other treatments.1

If you have any mood or behavior changes when taking Singulair, stop taking the drug and contact your doctor right away.1

These are not all the possible side effects of Singulair. Talk to your doctor about what to expect when taking Singulair. You also should call your doctor if you have any changes that concern you when taking Singulair.

Other things to know

Take Singulair exactly as prescribed by your doctor. Your doctor will tell you how much Singulair to take and when to take it. If you miss a dose of Singulair, take the next dose at your regular time. Do not take 2 doses at the same time. If you take too much Singulair, call your doctor right away.1

If you have asthma and aspirin makes your asthma symptoms worse, avoid taking aspirin or other medicines called non-steroidal anti-inflammatory (NSAIDs) while taking Singulair.1

Before taking Singulair, tell your doctor if you:1

  • Are allergic to aspirin.
  • Have phenylketonuria. Singulair chewable tablets contain aspartame, a source of phenylalanine.
  • Have or have had mental health issues.

There is not enough data to know if Singulair is safe to take while pregnant or breastfeeding. Before taking Singulair, tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.1

Before beginning treatment with asthma, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

For more information, read the full prescribing information of Singulair.

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