Singulair Lawsuit
montelukast (montelukast sodium) · Merck & Co. (brand now held by Organon, a Merck spinoff); also widely sold as generic montelukast · updated June 2026
Also covers montelukast, montelukast sodium, Singulair (montelukast) lawsuit claims.
Singulair (montelukast) is an asthma and allergy drug that the FDA placed under a Boxed Warning on March 4, 2020 for serious mental-health (neuropsychiatric) side effects. Lawsuits allege the manufacturer failed to adequately warn that montelukast can cause neuropsychiatric injuries such as depression and suicidal thoughts and behavior. Plaintiffs' claims are unproven and no court has found that montelukast caused these injuries. As of mid-2026 the cases are coordinated in New Jersey state court (Multicounty Litigation No. 637, In Re: Singulair Litigation, Atlantic County); there is no federal MDL and no global settlement.
This page is general information about ongoing litigation and FDA safety actions — not medical or legal advice, and not a statement that Singulair caused any injury. Allegations described here are claims that have not been proven in court. Always consult a licensed professional.
What the lawsuits allege
Plaintiffs allege that the manufacturer of Singulair (montelukast) knew or should have known of a risk of serious neuropsychiatric injuries — including depression, mood and behavior changes, and suicidal thoughts and actions — yet failed to adequately warn patients and prescribers before the FDA required a Boxed Warning in March 2020. They further allege that the drug was marketed and prescribed for milder conditions such as allergic rhinitis where, plaintiffs contend, the risks outweighed the benefits, and that the company should have disclosed these dangers sooner. These are unproven allegations; no court has established that montelukast caused the claimed injuries.
- Depression
- Suicidal thoughts and behavior (including completed suicide)
- Anxiety and agitation
- Aggression and irritability
- Sleep disturbances, nightmares, and insomnia
- Obsessive-compulsive symptoms
- Tics, tremors, and stuttering
- Other neuropsychiatric and mood/behavior changes
FDA action
On March 4, 2020, the FDA required a Boxed Warning — its most prominent warning — for montelukast (Singulair) and all montelukast generics, strengthening an existing warning about serious mental-health (neuropsychiatric) side effects, including agitation, aggression, depression, sleep disturbances, and suicidal thoughts and behavior. The FDA also required a patient Medication Guide and advised restricting use for allergic rhinitis, stating montelukast should be reserved for patients with allergic rhinitis who do not respond adequately to, or cannot tolerate, other therapies and should not be a first-choice treatment for mild allergic rhinitis. This is a label/safety action, not a recall; the drug remains on the U.S. market.
Verify against the current FDA-approved label: Singulair label on DailyMed (U.S. NLM).
Where the litigation stands
As of mid-2026 there is no federal multidistrict litigation (MDL): the U.S. Judicial Panel on Multidistrict Litigation has not consolidated Singulair cases. Instead, cases are coordinated in New Jersey state court as Multicounty Litigation No. 637 ("In Re: Singulair Litigation," master docket ATL-L-481-22), Superior Court of New Jersey, Law Division, Atlantic County. The litigation was centralized in Atlantic County by order of the New Jersey Supreme Court in early 2022 (the application cited roughly a few hundred cases around the time of consolidation; exact current case counts are not publicly reported). The court has established a bellwether trial discovery pool (an initial group of cases identified for discovery under its case-management orders), but as of mid-2026 no bellwether trial dates have been set and no global settlement has been reached; reports indicate a partial settlement covering some New Jersey cases was reached in 2025 while litigation otherwise continues. (Informational only; not legal advice.)
Case counts and MDL status are published by the U.S. Judicial Panel on Multidistrict Litigation — JPML pending MDLs. Any figure not on the court record is attributed to the secondary legal-press links below.
Who may be affected
The Singulair lawsuits are brought by people who say they used Singulair (montelukast (montelukast sodium)) and were later diagnosed with one or more of the alleged injuries above. Whether any individual situation could support a claim depends on the specific facts, the medical records, and each state's filing deadline (statute of limitations) — which can expire, so timing matters. Only a licensed attorney can evaluate a specific case. This page is general information, not legal advice.
Frequently asked
- What is the Singulair lawsuit about?
- Plaintiffs allege that the manufacturer of Singulair (montelukast) knew or should have known of a risk of serious neuropsychiatric injuries — including depression, mood and behavior changes, and suicidal thoughts and actions — yet failed to adequately warn patients and prescribers before the FDA required a Boxed Warning in March 2020. They further allege that the drug was marketed and prescribed for milder conditions such as allergic rhinitis where, plaintiffs contend, the risks outweighed the benefits, and that the company should have disclosed these dangers sooner. These are unproven allegations; no court has established that montelukast caused the claimed injuries. As of mid-2026 there is no federal multidistrict litigation (MDL): the U.S. Judicial Panel on Multidistrict Litigation has not consolidated Singulair cases. Instead, cases are coordinated in New Jersey state court as Multicounty Litigation No. 637 ("In Re: Singulair Litigation," master docket ATL-L-481-22), Superior Court of New Jersey, Law Division, Atlantic County. The litigation was centralized in Atlantic County by order of the New Jersey Supreme Court in early 2022 (the application cited roughly a few hundred cases around the time of consolidation; exact current case counts are not publicly reported). The court has established a bellwether trial discovery pool (an initial group of cases identified for discovery under its case-management orders), but as of mid-2026 no bellwether trial dates have been set and no global settlement has been reached; reports indicate a partial settlement covering some New Jersey cases was reached in 2025 while litigation otherwise continues. (Informational only; not legal advice.)
- What injuries are alleged in the Singulair lawsuits?
- Lawsuits allege depression, suicidal thoughts and behavior (including completed suicide), anxiety and agitation, aggression and irritability, sleep disturbances, nightmares, and insomnia, obsessive-compulsive symptoms, tics, tremors, and stuttering, other neuropsychiatric and mood/behavior changes. These are allegations; a court has not found that Singulair causes them.
- Has the FDA acted on Singulair?
- On March 4, 2020, the FDA required a Boxed Warning — its most prominent warning — for montelukast (Singulair) and all montelukast generics, strengthening an existing warning about serious mental-health (neuropsychiatric) side effects, including agitation, aggression, depression, sleep disturbances, and suicidal thoughts and behavior. The FDA also required a patient Medication Guide and advised restricting use for allergic rhinitis, stating montelukast should be reserved for patients with allergic rhinitis who do not respond adequately to, or cannot tolerate, other therapies and should not be a first-choice treatment for mild allergic rhinitis. This is a label/safety action, not a recall; the drug remains on the U.S. market.
- Is there a deadline to file a Singulair lawsuit?
- Yes — every state sets a filing deadline (statute of limitations) for product-injury claims, often running from the date of injury or diagnosis, and once it passes a claim is usually barred. The exact window varies by state and circumstances, so anyone considering a claim should check with a licensed attorney promptly. This is general information, not legal advice.
Other drug-safety & lawsuit trackers
Sources
- FDA — FDA requires Boxed Warning about serious mental health side effects for asthma and allergy drug montelukast (Singulair); advises restricting use for allergic rhinitis (March 4, 2020)
- FDA — Singulair (montelukast) and All Montelukast Generics: Strengthened Boxed Warning Due to Restricting Use for Allergic Rhinitis
- New Jersey Courts — Singulair Multicounty Litigation (MCL 637) Case Information