Montelukast, sold for decades under the brand name Singulair and taken by millions of people for asthma and seasonal allergies, carries one of the most serious safety labels the Food and Drug Administration can require. In March 2020, regulators strengthened the drug’s warnings to the agency’s highest level, a boxed warning, after concluding that montelukast was tied to serious mood and behavior changes, including suicidal thoughts and actions, in some patients. More than six years later, that warning remains on the label of every bottle of montelukast and its generics, and it continues to shape how doctors and families weigh the drug against its alternatives.
A 2020 Boxed Warning for a Drug Approved Since 1998
Montelukast was first approved by the FDA in 1998 and has been prescribed for asthma and allergic rhinitis, commonly known as hay fever, ever since. Warnings about possible mental health side effects were added to its prescribing information as early as 2008, but the FDA determined in 2020 that those earlier warnings were not registering with prescribers, patients, or caregivers. After reviewing case reports, running an observational safety study, and convening a panel of outside experts, the agency required a boxed warning, its most prominent alert, along with a new patient Medication Guide meant to make the risk impossible to miss at the pharmacy counter. The action, detailed in an FDA drug safety communication, covers montelukast in all its branded and generic forms.
Eighty-Two Suicides, and a More Complicated Picture
FDA reviewers combed through adverse event reports filed between the drug’s 1998 approval and May 2019 and identified 82 cases of completed suicide associated with montelukast use, including 45 in patients older than 17 and 19 in patients 17 or younger. Many of those reports described new agitation, aggression, or depression developing before the suicide occurred, though the agency noted that most of the case files lacked enough detail, such as timing or co-occurring conditions, to establish a clear cause. A separate, more rigorous safety study run through the FDA’s Sentinel surveillance system compared roughly 457,000 asthma patients on montelukast against patients on inhaled corticosteroids and did not find a significantly higher risk of inpatient depression or self-harm between the two groups. That nuance did not change the FDA’s decision, since the agency said the wide availability of other treatment options was reason enough to add the strongest possible warning while the underlying risk remained unresolved.
How Montelukast Works and Who Takes It
Montelukast belongs to a class of drugs called leukotriene receptor antagonists, which block leukotrienes, chemical messengers released by the immune system that narrow airways and drive inflammation during asthma attacks and allergic reactions. It is approved as a once-daily pill, chewable tablet, or oral granules for long-term asthma control in patients as young as one year old, for exercise-induced asthma in patients six and older, and for seasonal or year-round nasal allergy symptoms in patients as young as six months. That pill-based convenience, compared with inhalers that young children often struggle to use correctly, helped montelukast become one of the most widely dispensed asthma and allergy drugs in the country; roughly 9.3 million patients filled a montelukast prescription in 2018 alone, including about 2.3 million children under 17, a scale of use tracked in ongoing reviews of FDA drug safety alerts and warnings.
A New Limit on Allergic Rhinitis, Not on Asthma
The FDA drew a sharp line between the drug’s two main uses. For allergic rhinitis, the agency said montelukast should no longer be a first-choice option, since antihistamines such as loratadine, fexofenadine, and cetirizine, along with steroid nasal sprays like fluticasone and budesonide, treat the same sneezing and congestion without carrying the same psychiatric risk. Montelukast for hay fever is now supposed to be reserved for patients who cannot tolerate or have not responded to those alternatives. Asthma treatment received a lighter touch: because montelukast remains one of the few oral options for controlling asthma symptoms, and inhaled steroids do not work for everyone, the FDA stopped short of restricting its use for asthma and instead told prescribers to weigh the psychiatric risk against the benefit for each patient individually.
Guidance for Patients and Doctors Today
The Medication Guide the FDA now requires is supposed to be handed out with every montelukast prescription, spelling out warning signs that range from agitation and anxiety to nightmares, hallucinations, and suicidal thoughts. Prescribers are told to ask about any history of psychiatric illness before starting the drug, counsel every patient on the risk regardless of that history, and advise patients to stop the medication and call a doctor immediately if new behavioral or mood symptoms appear, since the FDA noted that side effects have occurred in patients with no prior mental health diagnosis. The agency also pointed to animal research showing montelukast can cross into brain tissue after oral dosing, one possible biological explanation for the psychiatric effects it was unable to fully resolve. Because the boxed warning has not been revised or removed since 2020, the same guidance still applies to anyone currently taking montelukast or considering it today.
This article was produced with the assistance of AI and reviewed by Morning Overview editors.
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