The FDA Black Box Warning
In March 2020, the FDA required Merck to add a black box warning to Singulair covering serious mental health side effects: agitation, aggression, hallucinations, depression, suicidal thoughts and behavior, and sleep problems. The FDA simultaneously restricted Singulair for allergic rhinitis to cases where other treatments are inadequate.
The 2020 action acknowledged that neuropsychiatric risks had been known for years but insufficiently communicated. This delayed warning is central to the litigation.
The Mass Tort Against Merck
Lawsuits allege Merck knew about neuropsychiatric adverse events from early post-market surveillance but failed to warn, continuing aggressive allergy marketing without disclosing mental health risks. Cases are consolidated in the District of New Jersey MDL. Bellwether preparation is underway.
Who Qualifies
Individuals who took Singulair and developed depression, suicidal ideation, or other behavioral changes during or after use -- or families of patients who died by suicide while taking Singulair -- may have claims. Medical documentation correlating drug use with psychiatric symptoms is essential.
Status 2026
The New Jersey MDL is active. No global settlement has been announced. Bellwether cases are in preparation.
How to Get Legal Help
If you believe you qualify based on the eligibility criteria described above, the next step is a free consultation with an experienced attorney. Most plaintiff-side attorneys handling these cases work on contingency -- meaning you pay nothing unless your case results in a recovery. Bring any relevant documentation including receipts, correspondence, or evidence of the harm you experienced. Related: Orilissa Lawsuit.
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Singulair Lawsuit: Mental Health Side Effects & Black Box Warning: Frequently Asked Questions
Answers to the most common questions about this case and your legal options.
Did Singulair cause mental health problems?
The FDA required a black box warning in 2020 acknowledging serious neuropsychiatric side effects.
Who can file a Singulair lawsuit?
Patients who took Singulair and developed serious psychiatric side effects, or families of suicide victims who were taking the drug.
When did the FDA add the black box warning?
March 2020.
Is there a Singulair MDL?
Yes -- cases are consolidated in the District of New Jersey.
Is Singulair still prescribed?
Yes, with the black box warning, restricted for allergic rhinitis to cases where other treatments are inadequate.