New Warnings on Singulair Allergy and Asthma Drug

Nana Addo, Ellen Pil, & Meg Seymour, PhD, National Center for Health Research

Black box warning for Singulair

Singulair, also known as montelukast, is widely used to treat allergies and asthma. In March 2020, the Food and Drug Administration (FDA) strengthened previous warnings for Singulair, requiring a “black box” warning. A black box warning (also called a boxed warning) is FDA’s strongest warning, similar to the ones used for cigarettes. It warns about serious risks of a medication or treatment. The black box warning for Singulair describes psychiatric side effects such as aggression, depression, agitation, sleep disturbances, suicidal thoughts, and suicide. You can read Singulair’s complete black box warning here

The FDA advises that Singulair should not be the first choice treatment for mild allergic rhinitis, which is another name for seasonal allergies and hay fever. That is the advice FDA gives when a treatment is not as safe or not as effective as an alternative treatment that is available. The FDA also recommends that healthcare providers weigh the potential risks and benefits before prescribing Singulair for asthma.1

What are the risks? 

Any person can report problems arising from the use of a medication or medical device to the FDA. These side effects or complications are called “adverse events.” Adverse events can be reported using FDA’s MedWatch program through this website. Of the over 19,000 reports of adverse events that FDA has received since the drug’s approval in 1998, more than 10,000 of those reports have been about psychiatric or nervous system adverse events. They included aggression, irritability, agitation, disorientation, attention disturbances, stuttering, hallucinations, insomnia, memory impairment, obsessive-compulsive symptoms, anxiety, depression, suicidal thoughts, and even suicide.  More than 7,000 of those adverse events are considered serious, and they occurred almost equally in adults and children.2  From 1998 to 2019, FDA received reports of 82 suicides among people using Singulair. Only 64 reports of suicides included the patient’s age, but 19 of those were in patients ages 16 and younger. Most of the patients who committed suicide had no history of mental illness.2

When Singulair was approved, these risks were not known or well understood. These serious adverse events were revealed when patients and parents of patients brought attention to them, leading to more research. Some of these side effects of Singulair appeared or continued even after patients stopped taking Singulair. Studies done in rats showed that Singulair enters and affects the brain1, but it is unclear whether it affects the human brain in permanent ways. However, researchers are now studying whether a version of this drug could help Alzheimer’s patients, which indicates a belief that it can have a long-term impact on the human brain, whether positive or negative.3

In 2019, the National Center for Health Research testified before the FDA about these neuropsychiatric side effects, urging that the FDA require a brief and easy-to-understand medication guide to be provided to patients before Singulair is prescribed to them. You can read that testimony here. The FDA has since decided that a medication guide outlining the risks will be given to everyone who is prescribed Singulair. You can read the medication guide here

The bottom line

Given the risks, the FDA has determined that Singulair should not be the first choice for treatment for those with allergies. Instead, it should only be prescribed for allergies for patients who have not responded well to other treatments. Healthcare providers who are considering prescribing Singulair for asthma must consider the potential side effects.1,4

Healthcare providers prescribing Singulair should speak with their patients about the risks. If you or someone you know are using Singulair and experience any new or worsening symptoms, look at the risks listed on the label, and be sure to talk with your doctor about them. You should also report those side effects to FDA through their MedWatch program using this website. 


All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.



  1.     U.S. Food and Drug Administration. FDA requires Boxed Warning about serious mental health side effects for asthma and allergy drug montelukast (Singulair); advises restricting use for allergic rhinitis. March 2020.  
  2.     Biehl, Ann. “Neuropsychiatric Events Associated with Montelukast: Postmarketing Experience.” U.S. Food and Drug Administration. September 27, 2019. Presentation.
  3. National Institute on Aging. Montelukast Therapy for Alzheimer’s Disease. 2019.
  4. U.S. Food and Drug Administration. FDA Requires Stronger Warning About Risk of Neuropsychiatric Events Associated with Asthma and Allergy Medication Singulair and Generic Montelukast. March 2020.