People traveling in tropical areas who take the anti-malaria drug mefloquine appear to be prone to psychiatric events such as anxiety or psychosis, new research shows. Women and people with a psychiatric history seem especially vulnerable.

Although mefloquine’s effectiveness in preventing malaria is widely accepted, it’s unclear how well people tolerate the drug, Dr. Bruno H. Ch. Stricker and colleagues, from Erasmus University Medical Centre in Rotterdam, the Netherlands, note in the Journal of Clinical Psychiatry.

In particular, there have been concerns that the drug may trigger psychiatric symptoms.

To investigate, the researchers studied data reported to travel insurance companies. It included 111 subjects who had experienced a psychiatric event while traveling and 453 matched “controls” who had not.

The most common events were depression, anxiety attacks, psychosis and insomnia, but there were also several instances of collapse, hallucinations, disorientation and lethargy.

Overall, mefloquine use raised the risk of psychiatric events by 3.5-fold, the team found. However, among females and patients with a psychiatric history, the elevated risks were even higher.

“Despite the fact that mefloquine is contraindicated in persons with a history of psychiatric diseases, a substantial number of users of mefloquine had such a history,” the investigators point out.

“Since persons with a positive history of psychiatric diseases have a strong risk of relapse with mefloquine use, other antimalarial drugs should be prescribed to such individuals,” they say.

SOURCE: Journal of Clinical Psychiatry, February 2005.