Urgent Warnings for Common Allergy and Asthma Drug Escalate

Psychiatric symptoms—from nightmares and depression to suicidal thoughts—may affect users of a popular asthma and allergy medication.

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Millions take it for asthma and allergies, but Singulair is under scrutiny. The popular drug, prescribed for decades, is linked to an array of psychiatric symptoms—from nightmares and depression to suicidal thoughts.

As regulators slap its packaging with warnings of neuropsychiatric issues and patients recount similar experiences, a question looms: How did a once-celebrated treatment become problematic for some? As families seek answers, scientists work to unravel how a medication meant to ease breathing could cloud the mind.

FDA and Global Health Warnings

The Medicines and Healthcare Products Regulatory Agency (MHRA), a UK government agency, announced that more prominent warnings will be added to the information leaflet for the asthma drug montelukast, sold as Singulair.

Since its last drug safety update in 2019, the MHRA has received ongoing reports from patients and caregivers about neuropsychiatric risks. The MHRA’s review confirmed these risks are not well known. New boxed warnings are being added to make these risks more clear.

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Montelukast is associated with various side effects ranging from headaches, coughs, and stomach pains to flu-like symptoms. The boxed warnings highlight neuropsychiatric risks such as sleep disturbances, anxiousness, depression, agitation, attention or memory issues, insomnia, hallucinations, and suicidal behavior.

The U.S. Food and Drug Administration (FDA) has indicated that montelukast’s inhibition of the GPR17 receptor on neurons and glial cells could be linked to its adverse neuropsychiatric effects. This interaction is believed to disrupt normal brain functions, leading to various mental health symptoms.

“Healthcare professionals should inform patients of these potential side effects,” Alison Cave, MHRA’s chief safety officer, said in a statement. “Patients and carers should immediately speak to their prescriber or seek urgent medical attention if the patient experiences any neuropsychiatric symptoms while using montelukast.”

At least 13 other countries have issued similar safety communications. In 2020, the FDA implemented a boxed warning for montelukast, the highest safety warning that can be assigned to a medication. The FDA also mandated that all patients receive a medication guide, informing them about the drug’s uses, potential risks, and safe usage instructions.

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“The incidence of neuropsychiatric events associated with montelukast is unknown, but some reports are serious, and many patients and health care professionals are not fully aware of these risks,” Sally Seymour, director of the FBI’s Division of Pulmonary, Allergy, and Rheumatology Products, said in a statement. She emphasized that numerous other medications, which are safe and have a proven track record for treating allergies, are available.

In February, New York Attorney General Letitia James urged the FDA to take immediate further action regarding montelukast. Her letter drew attention to an increase in mental health incidents since the drug was assigned a black box warning, calling for enhanced safeguards and heightened awareness to protect young patients during a rising youth mental health crisis.

“Data accumulated since the 2020 black box warning suggest that the neuropsychiatric dangers posed by montelukast are consistent with these prior findings, and are, in fact, much greater for children than for adults,” the letter reads.

What Is Montelukast?

Introduced to the U.S. market in 1998, montelukast presented a new way to manage asthma and allergies. Its pill form, bypassing the complexities of inhalers, soon became a popular choice for children and older adults. Montelukast is also available in chewable tablets and granules that can be easily mixed with liquids or food, enhancing its accessibility and ease of use.

Montelukast, functioning as a leukotriene receptor antagonist, targets leukotrienes—key elements in the body’s inflammatory response to allergens. These chemicals tighten airway muscles and increase mucus production, leading to symptoms such as coughing and throat tightness. By blocking these problematic chemicals, montelukast alleviates the chronic symptoms of asthma and allergies. Unlike inhalers that offer immediate relief, montelukast is taken daily, providing consistent management and control of symptoms.

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“Montelukast is often prescribed for exercise-induced asthma and asthma combined with allergic rhinitis, especially when symptoms include post-nasal drip,” Dr. Gilman Allen, a pulmonary and critical care medicine physician at the University of Vermont Medical Center, told The Epoch Times. “Generally, it serves as a second-line treatment, following inhaled corticosteroids and long-acting beta-agonists.”

Discontinuing montelukast can lead to a challenging withdrawal period for some, with an initial worsening of symptoms. Some users report symptoms such as anxiety, agitation, and mood swings that may intensify before they begin to improve.

A May review of the FDA’s Adverse Events Reporting System by The Epoch Times revealed 34,618 adverse event reports associated with montelukast, with 28,262 marked as severe. More than 22 percent of these cases involved children under 17, and 1,184 deaths have been linked to the drug.

Despite the FDA’s black box warning, montelukast remains widely prescribed, with 31 million prescriptions issued in the United States in 2021 alone. A University of Oklahoma study on the effect of the warning revealed that while adverse effects decreased among children under 10, they increased in five out of eight mental health categories for youths aged 11 to 17. These findings suggest that the black box warning has been only marginally effective in reducing prescriptions and may not adequately mitigate risks.

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Initially produced by the pharmaceutical giant Merck, Singulair was acquired by the spinoff company Organon in 2021. Various companies now produce generic versions of the drug. As of 2023, the global montelukast market is valued at $4.1 billion and is expected to grow to $7.1 billion by 2033.

Organon didn’t respond to The Epoch Times’ requests for comment by press time.

How Montelukast May Affect the Brain and Mental Health

Ongoing research continues to explore how montelukast affects the brain and its pathways. Studies indicate that montelukast crosses the blood-brain barrier, potentially causing unintended problems in the brain.

A 2022 study published in Life Sciences identified 18 new metabolites of montelukast and confirmed that the drug interacts with glutathione, an essential brain antioxidant. This interaction suggests that montelukast may affect the brain’s detoxification processes, which rely on glutathione to neutralize toxins and reduce oxidative stress.

The study found that montelukast disrupts pathways critical for regulating stress responses via the hypothalamic-pituitary-adrenal axis, potentially leading to symptoms such as depression and anxiety. Additionally, it impairs mitochondrial function in neurons, which is crucial for energy production and cell health.

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Researchers noted that children are particularly susceptible to these adverse effects because of their developing brains and sensitivity to central nervous system interactions.

Patients and Families Share Experiences

At a May 2022 meeting of the FDA National Center for Toxicological Research Science Advisory Board, parents, caregivers, and affected individuals submitted 92 pages of testimonials detailing the psychological effects associated with montelukast. Close to 70 patients and caregivers provided detailed accounts of their experience taking the drug.

​​One account describes a mother witnessing the severe neuropsychiatric effects of montelukast on her daughter, portraying her distress at seeing her child transform from a vibrant young athlete to a person battling severe mental health issues.

“Bang, bang, bang ... over and over,” recounted the mother, describing the sound of her daughter banging her head against the wall “after a day of raging and confusion.”

The daughter’s prescribed medications failed to alleviate her distress, the mom said, and instead contributed to a spiraling decline in her mental and emotional well-being that led to multiple suicide attempts.

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“Our beautiful, little girl had turned into a raging and self-harming maniac,” she wrote, further describing the drastic change in her daughter’s personality and life prospects.

Upon learning about the drug’s potential side effects, the mother helped her daughter wean off of the drug in October 2020. Though her symptoms initially worsened, the mother observed a significant positive shift, writing: “For the first time in years, I saw a twinkle in her eye. I knew then that it may have indeed been this drug that had been destroying my daughter.”

Today, she has completed a year of college, and the family firmly believes the drug was at the root of her earlier struggles. Notably, her asthma, allergies, and previously unexplained rashes have also diminished or significantly improved since discontinuing the medication.

The Montelukast (Singulair) Side Effects Support and Discussion Group on Facebook, which has more than 21,000 members, reflects the extensive concerns surrounding the medication’s side effects.

Conflicting Research Muddies the Waters

Recent studies highlight a rise in mental health issues among montelukast users. A 2023 study in The Journal of Allergy and Clinical Immunology found young adults taking montelukast were 28 percent more likely to need psychiatric medications or hospital care for mental health problems than those not on the drug.

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A 2017 study in the European Respiratory Journal reported high rates of neuropsychiatric reactions such as irritability and sleep disturbances, leading to drug discontinuation. The authors noted, “The incidence of children on montelukast with drug cessation due to neuropsychiatric adverse events was >10%.”

“Discussing the potential risks of montelukast with patients is complex given the varied and conflicting data. For instance, a recent meta-analysis found no strong link between montelukast and neuropsychiatric events,” Dr. Allen told The Epoch Times. “Many patients are already on montelukast when they come to me, and I frequently discontinue its use because it often fails to significantly improve symptoms.”

Dr. Allen pointed to a 2023 study in Heliyon that aggregated data from 18 trials and found no significant increase in neuropsychiatric events among montelukast users compared to placebo groups. However, the researchers called for more comprehensive trials because of conflicting research and FDA advisories.

An analysis of 59 studies in the European Respiratory Review examined neuropsychiatric effects in asthma patients on montelukast. It found no significant link to suicide or depression but noted increased antidepressant prescriptions. Adult patients showed possible risks for anxiety and sleep disorders, though no similar findings were observed in children.

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The study stated, “However, the possibility of montelukast inducing suicide-related events in certain individuals should not be excluded, because current methodologies struggle to address differences in baseline characteristics at an individual level.”

Monitoring Montelukast: Key Considerations

A March 2020 drug safety communication from the FDA stated, “Because of the risk of mental health side effects, the benefits of montelukast may not outweigh the risks in some patients, particularly when the symptoms of disease may be mild and adequately treated with other medicines.” The FDA advises using montelukast only if other treatments, such as antihistamines, steroid nasal sprays, or allergy shots, are ineffective or not tolerated.

According to the communication, patients and caregivers should stop montelukast and consult a health care professional immediately if they notice behavior or mood changes. However, the FDA also cautions to “be aware that some patients have reported neuropsychiatric events after discontinuation of montelukast.”

The FDA urges patients and caregivers to report adverse reactions to health authorities. According to Dr. Celia Williams of the FDA’s Division of Drug Information, these reports can lead to FDA actions such as updating product labels with new warnings or issuing safety alerts. These measures help monitor product use, adjust usage recommendations, or sometimes advise stopping the product altogether.