Singulair is a common prescription medication that helps to prevent asthma attacks in people aged 12 months and over. It is also known as montelukast.

However, Singulair has severe side effects related to mood, which have caused controversy in recent years.

The drug can also provide relief for seasonal, indoor, and outdoor allergies. It can also prevent exercise-induced bronchospasm in adults and children aged 6 years or older.

Doctors prescribe Singulair on a long-term basis to treat asthma, and it can help relieve symptoms of allergic rhinitis, such as sneezing, stuffy and runny noses, and nasal itching.

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Singulair can offer protection or relief from asthma and allergy symptoms.

Singulair blocks the action of leukotrienes.

Leukotrienes are fatty signaling molecules that the body produces when there is inflammation. They are thought to play a key role in triggering asthma and hay fever symptoms.

These molecules contribute to the way asthma develops, causing a range of effects including:

  • inflammation and swelling in the airways
  • airflow obstruction
  • airway constriction
  • increased secretion and build-up of mucus

When a person inhales asthma triggers, such as pollen, the body reacts by releasing leukotrienes.

Leukotrienes cause swelling and redness in the lungs and airways. The muscles in the airways tighten, resulting in asthma symptoms, including:

  • shortness of breath
  • wheezing
  • coughing

When Singulair blocks leukotrines, it helps to prevent asthma symptoms.

The producers of Singulair advise taking the drug once a day, in the evening.

The drug is available in the following ways:

  • in granules for infants aged 12 to 23 months
  • a cherry-flavored chewable tablet for children aged 24 months to 14 years
  • a tablet that can be swallowed whole, starting at a 4-milligram (mg) dose for infants and rising to 10 mg for those aged 15 years and over

For people who are using Singulair to prevent exercise-induced asthma, it should be taken 2 hours before exercise. Keep a rescue inhaler on hand in case of a severe reaction. People who are already taking a daily dose should not take an additional prevention dose.

People taking Singulair to prevent asthma during physical activity should speak to their doctor before use.

Singulair does not act fast enough to treat an asthma attack immediately, so do not use it to treat sudden asthma attacks. Instead, use a rescue inhaler. These have a much quicker effect.

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Common side effects of taking Singulair include developing a cough or sore throat.

The most common side effects include:

  • a cough
  • diarrhea
  • ear infection
  • earache
  • sinus infection
  • sore throat
  • stomach pain
  • upper respiratory infection

Report the following adverse effects to a doctor:

  • a skin rash or hives
  • bruising
  • pain or muscle weakness
  • bleeding
  • red or pinpoint spots under the skin

Singulair has been linked to behavior and mood changes, including:

Children and younger people using the medication are particularly at risk of these side effects. In March 2020, the FDA strengthened their warning about the adverse effects.

The FDA also caution people not to stop taking Singulair without first discussing this with their healthcare provider.

Less common side effects include a possible increase in certain white blood cells and a risk of inflamed blood vessels throughout the body.

This can lead to numbness and tingling, flu-like symptoms, a rash, and inflamed sinuses.

Report any worsening asthma symptoms to a doctor. If Singulair triggers an allergic reaction, seek immediate medical assistance.

The chewable tablets contain a component of aspartame called phenylalanine. Some people are allergic to this substance and should not use Singulair.

Singulair, or montelukast, is a drug that gradually reduces the risk of asthma flare-ups by blocking the action of leukotrienes. These are fatty signaling molecules, which the body uses during inflammation and allergic reactions.

It is available as chewable tablets, granules, and regular tablets, depending on the age of the person with inflammation or asthma.

However, the FDA warns that Singulair can lead to severe side effects, including difficulties with psychological health, especially in young people.


Can I take Singulair while using other medications?


Singulair is safe to take with most medications.

Discuss all medications you are taking with your doctor and pharmacist to ensure that Singulair is safe to take with your medications.

Dena Westphalen, PharmD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.