Singulair (Montelukast): Side Effects, Interactions, and Overdose

What is montelukast used for?

Montelukast is used to treat or prevent asthma, to treat seasonal and year-round allergies, and to prevent difficulty breathing during exercise. The brand name for montelukast is Singulair^®. Montelukast comes in tablets, chewable tablets, and granules. Montelukast should not be used as a substitute for rescue medications such as albuterol during an asthma attack. 

Is Singulair an antihistamine? 

Singulair (montelukast) is not an antihistamine. Singulair is a leukotriene receptor blocker. Leukotriene is a chemical that the body releases when exposed to an allergen such as pollen. When leukotriene is released, it binds to the receptor and causes inflammation, smooth muscle contraction, and fluid buildup in the airway. Taking Singular prevents these reactions from occurring by binding to the receptors instead of leukotriene.

What are the side effects of montelukast?

Montelukast is usually well tolerated. Some common side effects reported are headaches, fever, sore throat, cough, and diarrhea.

What drugs should not be taken with montelukast? 

Montelukast is relatively safe to take with other medications. However, people who are sensitive or allergic to aspirin should avoid aspirin or NSAIDs such as ibuprofen while taking montelukast. 

Is it safe to take montelukast during pregnancy?

There is limited information available on the safety of montelukast use during pregnancy. Animal studies involving rats and rabbits have not shown an association between montelukast use and fetal harm, but there are some reports of birth defects in humans born to mothers who took montelukast along with other asthma medications. Because of this, pregnant women should always discuss the risks and benefits of taking montelukast during pregnancy with their physician. There is a registry that monitors pregnancy outcomes in women who take montelukast or other medications. To learn more or join the registry, call 1-800-986-8999 or visit http://mothertobaby.org/ongoing-study/asthma. 

Montelukast warnings: What is Singulair’s black box warning?

There is one black box warning to be aware of when taking montelukast. There have been reports of agitation, aggression, depression, trouble sleeping, and suicidal thoughts/behaviors in individuals who take montelukast. Note any changes in behavior that occur while taking this medication. If there are any changes in behavior, stop taking montelukast and reach out to a physician as soon as possible.

What happens if you take too much montelukast? 

If you take too much montelukast, you may be at a higher risk of developing unwanted side effects. In some studies, daily dosing up to 200 mg was safe in adult patients. Another study analyzed montelukast exposures involving children five years old or younger and concluded that doses up to 536 mg were unlikely to have serious side effects. Common side effects reported in these cases were drowsiness, agitation, nausea, stomach pain, and vomiting. 

What to do if someone takes too much Montelukast or takes it by accident 

If someone takes too much montelukast or takes it by accident, get guidance from Poison Control immediately. Help from Poison Control can be obtained online at www.poison.org or by phone at 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.

Singulair^® is a registered trademark of MERCK & CO., Inc.

Lily Doan, PharmD Candidate 2023
UNM Pharmacy Student