Montelukast, sold under the brand name Singulair, carries the FDA’s most serious warning label — a Black Box Warning — because it can cause severe neuropsychiatric side effects including suicidal thoughts and actions, depression, hallucinations, and memory problems. If your child takes this drug for asthma or allergies, you need to understand what this warning means and what to watch for, because some of these reactions can be sudden, severe, and in rare cases, fatal. The FDA identified 82 cases of completed suicide associated with montelukast use in its adverse event reporting database, and in November 2024, FDA researchers presented new evidence that the drug binds to receptors in brain regions governing mood, impulse control, cognition, and sleep. This is not a fringe concern about an obscure medication.
In 2022, approximately 29 million prescriptions for montelukast were dispensed in the United States, making it one of the most widely prescribed drugs in the country. It is approved for children as young as 12 months for asthma and 6 months for allergic rhinitis. Many parents have no idea their child’s allergy pill carries a warning typically reserved for drugs with life-threatening risks. This article covers what the Black Box Warning actually says, the neuropsychiatric side effects documented by the FDA, the latest brain research from 2024, what the population-level studies show (and where they fall short), the current litigation against manufacturer Merck, and the specific steps parents should take right now.
Table of Contents
- Why Did the FDA Add a Black Box Warning to Montelukast (Singulair)?
- What Neuropsychiatric Side Effects Has the FDA Linked to Montelukast?
- What Did the 2024 FDA Brain Study Reveal About Montelukast?
- What Do the Population-Level Studies Actually Show — and Where Do They Fall Short?
- What Is the Current Legal Landscape for Singulair Lawsuits?
- What Are the Alternatives to Montelukast for Children?
- What Should Parents Be Watching For Going Forward?
- Conclusion
- Frequently Asked Questions
Why Did the FDA Add a Black Box Warning to Montelukast (Singulair)?
On March 4, 2020, the FDA took the unusual step of adding a Boxed Warning — its most serious category of drug warning — to montelukast. This was not a new discovery. Reports of neuropsychiatric events had been accumulating for years, and the FDA had previously added warnings to the prescribing label in 2008 and 2009. But the agency concluded that many healthcare providers and patients still did not fully appreciate the severity of the risks. The Black Box Warning was accompanied by a requirement that pharmacies provide a Medication Guide to patients every time the drug is dispensed, and a new restriction: the FDA now advises that montelukast should only be prescribed for allergic rhinitis in patients who have had an inadequate response to or cannot tolerate alternative therapies. For asthma, it remains an approved treatment, but the risk calculus changed significantly.
To put this in context, Black Box Warnings are rare. The FDA reserves them for situations where a drug’s side effects can be serious enough to cause permanent harm or death, and where the prescriber and patient must weigh the risk against the benefit before every prescription. Compare montelukast’s situation to a drug like ibuprofen, which carries cardiovascular and gastrointestinal warnings but no Black Box. The FDA’s decision to elevate montelukast’s warning signals that the agency considers these neuropsychiatric effects to be in a different category of severity. For parents whose children take this medication solely for seasonal allergies — not asthma — the FDA’s guidance is clear: try something else first.
What Neuropsychiatric Side Effects Has the FDA Linked to Montelukast?
The list of neuropsychiatric side effects associated with montelukast is long and spans a wide range of severity. The FDA’s warning specifically names agitation, including aggressive behavior and hostility; attention problems; bad or vivid dreams; depression; disorientation and confusion; anxiety; hallucinations; insomnia and other sleep disturbances; memory problems; obsessive-compulsive symptoms; stuttering; suicidal thoughts and actions, including completed suicide; and tremor or tics. For parents, the most alarming aspect of this list is its breadth. A child might not report suicidal thoughts, but a parent might notice new aggression, nightmares, or sudden anxiety and not connect it to an allergy medication. One critical detail the FDA emphasizes: these neuropsychiatric events have been reported in patients with and without pre-existing psychiatric conditions. A child does not need to have a history of depression or anxiety to be at risk.
There is also a troubling pattern in the case reports — some symptoms have occurred after discontinuation of the drug, not just during active use. This means that stopping montelukast does not guarantee immediate resolution of symptoms, and parents should remain vigilant even after their child has been taken off the medication. However, if your child has been taking montelukast for months or years without any behavioral changes, that does not mean the risk is zero going forward. New symptoms can emerge at any point during treatment. The practical challenge is that many of these symptoms — attention problems, bad dreams, irritability — overlap with normal childhood behavior or other conditions like ADHD. This makes it easy for parents and even clinicians to attribute the changes to something else entirely. If your child is on montelukast and you notice any new or worsening behavioral or mood changes, the FDA’s guidance is unambiguous: stop the medication and contact a healthcare provider immediately.
What Did the 2024 FDA Brain Study Reveal About Montelukast?
In November 2024, FDA researchers presented findings at the American College of Toxicology meeting in Austin, Texas, that gave new biological plausibility to the neuropsychiatric concerns. The researchers found that montelukast has significant binding to multiple receptors in the brain, including G-protein coupled receptors and neurotransmitter transporters involved in psychiatric pathways. more specifically, the drug was found at highest concentrations in brain regions known to be involved in psychiatric effects — the areas that govern mood, impulse control, cognition, and sleep. The lab tests also confirmed earlier animal research showing that montelukast penetrates the brains of rats. For years, skeptics of the neuropsychiatric warnings argued that montelukast was designed to work in the lungs, not the brain, and that the reported side effects might be coincidental. The 2024 findings directly challenge that argument.
If montelukast concentrates in brain regions responsible for mood and impulse control, the mechanism for psychiatric side effects becomes much harder to dismiss. These are preliminary findings that have not yet been formally published in a peer-reviewed journal, so they should be interpreted with appropriate caution. But they represent the most significant development in understanding the drug’s neurological profile since the Black Box Warning was added. For a brain health audience, this research is particularly relevant. The finding that montelukast binds to neurotransmitter transporters and concentrates in specific brain regions raises questions not just about acute psychiatric effects but about potential long-term neurological consequences, especially in developing brains. No study has yet directly examined whether prolonged montelukast use in childhood affects cognitive development or long-term brain health, but the 2024 findings make that a question worth asking.
What Do the Population-Level Studies Actually Show — and Where Do They Fall Short?
Parents researching montelukast will encounter studies that seem to contradict the FDA’s warnings. A 2023 systematic review of 59 studies published in Respiratory Research found that montelukast was not associated with an increased risk of suicide-related events at a population-wide level. Similarly, a January 2025 study published in Pediatrics examined children specifically and found no statistically significant association between montelukast use and neuropsychiatric adverse events in routine clinical practice. The hazard ratio for suicide and suicidal actions was 1.31, meaning the risk was elevated by about 31 percent compared to non-users, but the confidence interval ranged from 0.64 to 2.69, meaning the result was not statistically significant. These studies are important, but they have a critical limitation that parents need to understand. Population-level studies are designed to detect average effects across large groups. They are not designed to identify rare but severe reactions in vulnerable subgroups.
A drug could cause devastating psychiatric effects in one out of every thousand children and still show no statistically significant signal in a population study, especially if the affected children are not evenly distributed across the study population. The 82 completed suicides in the FDA’s adverse event database are real, documented cases — and they represent only the cases that were actually reported. The FDA estimates that its FAERS database captures only a fraction of actual adverse events. The tradeoff here is real. For a child with moderate to severe asthma and no good alternatives, montelukast may still be the right choice even with the risks. For a child taking it for mild seasonal allergies, the risk-benefit calculation is very different when inhaled corticosteroids, antihistamines, and other treatments are available. The population studies should reassure parents that the absolute risk is low, but they should not be used to dismiss the possibility that their individual child could be the one who reacts severely.
What Is the Current Legal Landscape for Singulair Lawsuits?
Families affected by montelukast’s neuropsychiatric side effects have turned to the courts, alleging that manufacturer Merck designed a defective drug, acted negligently, and failed to adequately warn about risks including tics, tremors, stuttering, obsessive-compulsive disorder, depression, and suicidality. As of early 2026, there is no federal multidistrict litigation consolidation for Singulair lawsuits. However, New Jersey designated Singulair cases as multicounty litigation on January 4, 2022, centralizing them in Atlantic County. No global settlement or bellwether trials have occurred. Cases are being handled individually, which means progress is slow and outcomes vary.
For parents considering legal action, this is both a limitation and an opportunity. The lack of a federal MDL means there is no centralized discovery process or coordinated trial schedule that could accelerate resolution. On the other hand, the 2024 FDA brain study could become a significant piece of evidence in future cases, providing a biological mechanism that connects the drug to the reported psychiatric effects. Parents who documented their child’s symptoms, kept records of prescriptions, and consulted with healthcare providers about the connection to montelukast will be in a stronger position. One important warning: the legal landscape for pharmaceutical litigation changes frequently, and statutes of limitations vary by state. Families who believe their child was harmed by montelukast should consult with a qualified attorney sooner rather than later, as waiting too long can forfeit the right to file a claim entirely.
What Are the Alternatives to Montelukast for Children?
The FDA’s updated guidance makes clear that montelukast should not be the first-line treatment for allergic rhinitis. For children with seasonal or perennial allergies, inhaled corticosteroid nasal sprays such as fluticasone and mometasone are considered first-line treatments with well-established safety profiles. Second-generation antihistamines like cetirizine and loratadine are also widely used and do not carry neuropsychiatric Black Box Warnings. For children with asthma, inhaled corticosteroids remain the cornerstone of long-term control therapy, and combination inhalers with long-acting beta-agonists are available for children who need additional control.
The comparison matters. Montelukast was popular in part because it is a once-daily chewable tablet, which is easier for many children than a nasal spray or inhaler. Convenience is a real factor in medication adherence, especially with young children. But convenience should not outweigh safety when effective alternatives exist. If your child’s current prescriber is reluctant to switch medications, consider seeking a second opinion from a pediatric allergist or pulmonologist who can evaluate the full range of treatment options.
What Should Parents Be Watching For Going Forward?
The montelukast story is not over. The 2024 FDA brain study findings are preliminary and have not yet been published in a peer-reviewed journal. If and when they are, they could trigger additional regulatory action — potentially further restricting the drug’s approved indications or requiring new safety studies, particularly in pediatric populations. Merck’s response to these findings and the ongoing litigation will also shape the landscape in the coming years.
For parents whose children are currently taking montelukast, the most important action is not panic but vigilance. Talk to your child’s doctor about whether the drug is truly necessary or whether a safer alternative would work. Monitor your child for any changes in mood, behavior, sleep, or thinking — and take those changes seriously even if they seem mild. The gap between what population studies show and what individual families experience is real, and your child’s safety depends on you being informed, observant, and willing to act.
Conclusion
Montelukast carries a Black Box Warning for good reason. The FDA has documented serious neuropsychiatric side effects including suicidal thoughts and actions, depression, hallucinations, memory problems, and behavioral changes in children and adults. The 2024 FDA brain study adds biological evidence that the drug penetrates and binds to receptors in brain regions governing mood, cognition, and impulse control. While population-level studies suggest the absolute risk is low, individual cases — including 82 reported completed suicides — demonstrate that the consequences can be devastating for those who are affected.
If your child takes montelukast, have a conversation with their healthcare provider about whether the benefits outweigh the risks for their specific situation. For allergic rhinitis, the FDA itself says to try other treatments first. For asthma, weigh the options carefully with a specialist. Keep records of any behavioral or mood changes, and do not hesitate to stop the medication and seek medical attention if something seems wrong. No allergy medication is worth a child’s mental health, and no parent should learn about a Black Box Warning only after their child has been harmed.
Frequently Asked Questions
Can montelukast cause permanent neuropsychiatric damage in children?
The FDA has noted that some neuropsychiatric symptoms persist even after the drug is discontinued, but there is no definitive long-term study on permanent effects. The 2024 FDA brain study raises new questions about the drug’s impact on brain regions involved in cognition and mood, but these findings are preliminary. Parents should report any lasting symptoms to their child’s doctor and to the FDA’s MedWatch program.
My child has been on Singulair for years with no problems. Should I stop it?
Not necessarily without consulting your doctor. The absence of symptoms so far does not eliminate future risk, but abruptly stopping asthma medication can also be dangerous. Talk to your child’s prescriber about whether montelukast is still the best option, and discuss a plan for transitioning to an alternative if appropriate.
How common are the serious side effects?
Population-level studies suggest the overall risk is low. A 2025 study in Pediatrics found no statistically significant increase in neuropsychiatric events among children taking montelukast, though the hazard ratio for suicidal events was elevated at 1.31. However, the FDA’s adverse event database contains 82 reports of completed suicide, and underreporting is a known limitation of that system.
Is montelukast safe for toddlers and infants?
Montelukast is FDA-approved for asthma in children as young as 12 months and for allergic rhinitis in children as young as 6 months. The Black Box Warning applies to all age groups. Young children cannot report psychiatric symptoms, making parental observation especially critical.
Are there any lawsuits I can join?
There is no federal MDL for Singulair as of early 2026. New Jersey has centralized cases as multicounty litigation in Atlantic County. Cases are being handled individually. If you believe your child was harmed, consult a pharmaceutical litigation attorney in your state to discuss your options and applicable deadlines.
Did the FDA consider pulling montelukast from the market?
The FDA chose to add the Black Box Warning and restrict the allergic rhinitis indication rather than withdraw the drug. For patients with asthma who have not responded to other treatments, montelukast still provides a meaningful benefit. The FDA’s approach was to ensure that the risks are clearly communicated so that prescribers and patients can make informed decisions.
