Singulair: 7 things you should know
Medically reviewed by Carmen Fookes, BPharm. Last updated on April 10, 2020.
1. How it works
- Singulair is a brand (trade) name for montelukast. Montelukast inhibits specific receptors in the airways called leukotriene receptors. These receptors are affected by substances released during inflammation and following exposure to an allergen. By blocking these receptors, montelukast relieves airway edema, relaxes smooth muscle and dampens down the inflammatory response.
- Singulair belongs to the class of medicines known as oral leukotriene receptor antagonists.
- Used for the maintenance treatment of asthma in adults and children aged older than 12 months.
- May also be used to treat exercise-induced bronchospasm (EIB) in adults and children aged six years and older. A single dose should be taken at least two hours before exercise.
- May also be given as a preventative for seasonal allergic rhinitis (hay fever) in adults and children aged two years of age and older, and perennial allergic rhinitis in adults and children aged six months and older.
- Available as tablets, chewable tablets, and oral granules. Granules may be dissolved in baby formula or breast milk for administration to children older than 12 months.
- No dosage adjustment is necessary for people with kidney disease or with mild-to-moderate liver disease.
- Singulair is available as a generic under the name montelukast.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- A headache, abdominal pain, influenza, dyspepsia, cough, an increased bleeding tendency, a rash, and laboratory test disturbances.
- May cause psychiatric-type effects including agitation, aggressive behavior, anxiety, depression, abnormal dreams, and hallucinations. These have been reported in people of all ages taking Singulair.
- May cause dizziness or drowsiness and affect a person's ability to drive and operate machinery.
- Not a treatment for an acute asthma attack. Albuterol or another short-acting bronchodilator should be used instead.
- May not be suitable for some people including those with liver disease, a history of reaction to Singulair or other foods or dyes, or women who are pregnant or planning to become pregnant, or breastfeeding.
- Singulair may interact with some other medications including carbamazepine, phenytoin, phenobarbital, rifampin, repaglinide, rosiglitazone, and paclitaxel.
Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects
- May be administered with or without food. Available as tablets, chewable tablets, and oral granules. The granules can be administered directly into the mouth or dissolved in a teaspoonful of breast milk or formula, or soft food such as applesauce, carrots, rice or ice cream. Once the packet is opened, the contents should be taken within 15 minutes. Discard any unused portion.
- Take once daily in the evening when used as a preventative treatment for asthma. Take Singulair daily as prescribed, even if you have no symptoms of asthma. Do not increase or decrease the dose of Singulair without your doctor's permission and continue to take all other asthma medications as prescribed.
- Take at least two hours prior to exercise when given to prevent against exercise-induced bronchoconstriction.
- When given for allergic rhinitis, only a single dose should be taken daily but it may be dosed morning or evening depending on patient preference.
- Take exactly as prescribed when given for asthma, even if you are asymptomatic. Continue taking as prescribed even during an acute asthma attack.
- You should talk with your doctor beforehand about what to do if you have an acute asthma attack. This should include taking your short-acting bronchodilator medicine (commonly albuterol) as prescribed. Singulair is not for use during an acute attack. Talk to your doctor if you regularly need to take more of your acute asthma treatment.
- Notify your doctor if you experience any neuropsychiatric effects (such as aggression, anxiety, depression, tics, thoughts of suicide, or hallucinations) while taking Singulair. Also, tell your doctor if you develop any symptoms of an allergic reaction including a rash or breathing problems; or side effects such as an abnormal heartbeat, unusual bruising, yellowing of the skin or eye, trouble sleeping or a tingling or twitching in your fingers and toes.
- Avoid driving or operating machinery if Singulair makes you drowsy or dizzy.
- If you know you are sensitive to aspirin or other NSAIDs, continue to avoid these while taking Singulair.
- Phenylketonurics note: The 4mg and 5mg chewable tablets contain phenylalanine.
6. Response and Effectiveness
- Peak concentrations of Singulair are reached within three to four hours. It may take several weeks before improvements in breathing measurements, such as forced expiratory volume [FEV]) are noted.
Medicines that interact with Singulair may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with Singulair. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with Singulair include:
- anticonvulsants, such as carbamazepine, divalproex, fosphenytoin, or phenytoin
- antifungals, such as fluconazole, miconazole, or voriconazole
- fibrates, such as gemfibrozil
- heart medications, such as amiodarone
- HIV medications, such as efavirenz
- St. John's wort
Note that this list is not all-inclusive and includes only common medications that may interact with Singulair. You should refer to the prescribing information for Singulair for a complete list of interactions.
More about Singulair (montelukast)
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 181 Reviews
- Generic Availability
- Drug class: leukotriene modifiers
- FDA Alerts (4)
Related treatment guides
Singulair (montelukast) [Package Insert]. Revised 02/2019. Merck Sharp & Dohme Corp https://www.drugs.com/pro/singulair.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Singulair only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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