Singulair’s Mental Health Risks

Singulair (montelukast) is a prescription medication. It was FDA-approved in 1998 to prevent difficulty breathing during exercise and to treat asthma and symptoms of seasonal and year-round allergies. The drug is controversial because it’s linked to serious neuropsychiatric effects. In extreme cases, the drug was linked to suicidal thoughts. Some patients, including children, committed suicide after taking the medication.

Doctors may prescribe Singulair to children because it’s available as a cherry-flavored chewable tablet. In 2018 alone, about 2.3 million children younger than 17 received a prescription. Parents reported several mental health effects after their children took Singulair.

These reports and the FDA’s review of data led the FDA to add a boxed warning (also called a black box warning) — the agency’s most serious safety-related warning — to Singulair in 2020 for serious neuropsychiatric events.

Some individuals and parents have filed Singulair lawsuits against the drug’s maker, Merck, for neuropsychiatric effects such as depression, suicidality, tremors, stuttering and obsessive compulsive disorder.

Many of these lawsuits were consolidated in multicounty litigation (MCL) in New Jersey in 2022, and the MCL is still open.

Singulair’s mental health side effects went unnoticed for years in part because the FDA didn’t issue its first warning and label update for the drug until 2008 — 10 years after the drug hit the market.

Although the first label update was about reported neuropsychiatric events, it wasn’t until 2020 that the FDA added the boxed warning for neuropsychiatric side effects. This warning came in response to growing postmarketing reports and parents describing these symptoms in their children.

Additionally, while researchers conducted early clinical trials on rats, these results don’t always translate directly to humans. Although these studies showed potential drug buildup in the rodents’ brains, human trials didn’t initially reveal this. Psychiatric effects in people can manifest slowly and inconsistently, and the drug’s original safety tests focused more on physical side effects than mental impacts.

The FDA added Singulair’s black box warning in 2020 for neuropsychiatric events. Prior to that, the agency had other label changes and advisory meetings about these side effects.

Singulair’s neuropsychiatric side effects were serious enough that Darsana Srinivasan, Chief of the Health Care Bureau in the New York Attorney General’s Office, addressed her concerns in a letter to then-FDA Commissioner Robert M. Califf in February 2024.

Srinivasan highlighted that reports showed that side effects disproportionately affect children. She said that the boxed warning added in 2020 wasn’t enough.

The Health Care Bureau Chief called on the FDA to further evaluate the risks and benefits in children under 18. Srinivasan wanted the organization to determine if the label should say the drug should not be used in children under 18, among other actions.

While anyone may experience Singulair’s neuropsychiatric side effects, children ages 2 through 18 are most at risk.

Researchers still aren’t sure exactly how montelukast affects the brain to cause mental health side effects, but one study in Life Sciences theorized that the drug affects brain chemicals. This is most apparent in the underdeveloped brains of children, making them more likely to suffer these side effects.

Additionally, people with pre-existing mental health conditions may be at increased risk. Patients should tell their prescribers about their mental health history before taking the drug.

If you or your child experiences mood or behavior changes while taking Singulair or its generic montelukast, the FDA advises stopping the medication and contacting your healthcare provider immediately.

Make sure to document all symptoms and behaviors to discuss with your medical provider. You can report the side effects to the FDA’s MedWatch System.

If you are interested in filing a Singulair lawsuit because of serious neuropsychiatric side effects, speak to an attorney right away. Your time may be limited to file a claim.