Singulair Medication Potentially Linked to Mental Illnesses

In May 2021, Rachel McHenry and her mother, Brenda Lee Danielson, sued Merck & Co. over the psychiatric effects of the popular asthma medication, Singulair. McHenry and Danielson sued in New Jersey state court alleging that McHenry’s use of Singulair as a teenager led to her neuropsychiatric disorders. The complaint alleges design defects, failure to warn, negligence, breaches of express and implied warranties. 

The lawsuit alleges that the ongoing testing of the drug’s active ingredient, montelukast, indicates a link between its use and the psychiatric effects McHenry suffers from. The complaint states that “Many of these studies have demonstrated a correlation–and some show causation–between Singulair usage and development of neuropsychiatric events. Defendants have ignored these studies.” 

The lawsuit also alleges that Merck acknowledged “montelukast’s possible effects on cerebral spasm” in its patent application in 1996. However, Merck received the patent and Singulair entered the market in 1998. The complaint alleges that Merck “slowly and belatedly added grossly insufficient warnings regarding neuropsychiatric events to the product label.” 

The plaintiffs’ attorney, Kimberly Beck, claims that there are nine other lawsuits filed in state court over Singulair’s side effects and there is a plan in the works to request a multicounty litigation designation. 

Beck stated: “We have convincing evidence that Merck knew Singulair would pass the blood-brain barrier and therefore could cause neurological side effects, as early as 1996. If Merck had properly warned prescribers, many children would not have been prescribed Singulair and not suffered a permanent neurologic injury.”

In October 2020, Stephanie Hammer filed a lawsuit against Merck on behalf of her minor son, R.S.B. The lawsuit was filed in the U.S. District Court for the Eastern District of Wisconsin and alleges that Merck failed to warn about the risks of suicidal thoughts and other neuropsychiatric injuries. 

R.S.B. was prescribed Singulair to treat his asthma and hay fever symptoms in December 2010 and used the medication until August 2012. He was admitted to a psychiatric care facility due to suicidal and homicidal thoughts. He was diagnosed with major depressive disorder, anxiety disorder, obsessive-compulsive disorder, homicidal thoughts, and other psychiatric disorders. 

The lawsuit states that “Singulair causes a decrease in neuronal proliferation (nerve growth) in the hippocampal neurogenic zone (part of the brain largely involved in things from short-term memory to long-term memory, and spatial memory). In short, giving Singulair to healthy children can delay their nerve growth in the part of the brain that is most important to short-term memory, long-term memory, and spatial memory. Furthermore, alterations in the hippocampus have been linked to a variety of cognitive pathologies such as anxiety, depression, addiction and neurodegenerative diseases such as Parkinson’s.

The FDA’s Concerns

By 2009, there were concerns that Singulair may have an adverse effect on patients’ mental health. In 2009, the FDA updated Singulair’s list of potential side effects to include “neuropsychiatric events.” 

Since then, neuropsychiatric incidents reported by Singulair patients were reported to the FDA’s Sentinel Initiative in addition to concerning reports from animal studies and suicide reports. The FDA identified 82 cases where suicide was linked to montelukast use, of which 45 of the cases involved patients older than 17 and 19 cases involved patients younger than 17. There were 18 cases that did not report the patient’s page. A study of montelukast in mice found the drug molecule inside the brain–meaning that the drug can cross the blood-brain barrier. This suggested to scientists that montelukast/Singulair could enter and harm the brain. 

In March 2020, the FDA began to require the “black box” warning label (the FDA’s highest danger advisory label) on every unit of Singulair. Users are warned of the potential for severe mental health symptoms such as suicidal ideation and attempted suicide. As a result, the FDA now advises against the use of Singulair to treat seasonal or chronic allergies unless the patient does not respond to any other medications. The FDA also required that a Medication Guide be given to new patients to warn about the medication’s risks. 

Singulair’s side effects include

  • Agitation, including aggressive behavior or hostility 
  • Attention problems 
  • Bad or vivid dreams 
  • Depression 
  • Disorientation or confusion 
  • Feeling anxious 
  • Hallucinations (seeing or hearing things that are not really there) 
  • Irritability 
  • Memory problems 
  • Obsessive-compulsive symptoms 
  • Restlessness 
  • Sleepwalking 
  • Stuttering 
  • Suicidal thoughts and actions 
  • Tremor or shakiness
  • Trouble sleeping
  • Uncontrolled muscle movements

Background on Singulair

Singulair and its generic version, montelukast, is a prescription medication used to prevent asthma symptoms such as difficulty breathing, chest tightness, wheezing and coughing. Singulair is often also used to prevent asthma symptoms from occurring during exercise and to relieve allergic rhinitis (hay fever). 

Merck & Co. Inc.’s subsidiary, Merck Sharp & Dohme Corp., markets Singulair in the United States. The medication was originally approved by the U.S. Food and Drug Administration (FDA) in 1998. 

Johns Hopkins Bloomberg School of Public Health and co-director of Center for Drug Safety and Effectiveness, Dr. Caleb Alexander, explained how Singulair works: “While Singulair is not a steroid and is not typically considered an immunosuppressant, it nevertheless does interfere with immune pathways by limiting the production of leukotrienes, chemicals in the body that are part of the ‘inflammatory cascade.’” Essentially, the body releases leukotrienes after coming into contact with an allergen. The chemicals make the airways tighten and produce fluid and mucus. However, Singulair blocks these chemicals to control asthma and allergy symptoms. 

Singulair is used to prevent asthma attacks and for long-term treatment of asthma in adults and children one year and older. It is also approved to prevent exercise-induced asthma in patients 6 years and older. In addition, Singulair has been approved to help control the nasal symptoms of seasonal outdoor allergies in patients 2 years and older and year-round indoor allergies in patients 6 months or older. Singulair works to improve asthma and allergic rhinitis symptoms by blocking the symptoms in the body that cause them.

How GoldenbergLaw Can Help

If you or a loved one suffered mental health issues after taking Singulair, contact the Dangerous Drug Attorneys at GoldenbergLaw. Our team has over thirty years of experience providing clients with the Gold standard of advocacy. Contact us today for a free consultation!

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