The Food and Drug Administration announced on Monday that a commonly used anti-malaria drug must carry the so-called black box warning on its label because of the danger that the drug could cause serious neurological and psychiatric side effects, some of which can become permanent.

The drug, mefloquine hydrochloride — better known by its brand name, Lariam — has long been known to cause side effects that include ringing in the ears, depression and hallucinations. The announcement on Monday clarified that some of the symptoms, like dizziness and loss of balance, could become permanent. And some of the psychiatric symptoms, the agency said, could persist for months or even years after a patient ceases taking the drug. A black box warning is reserved for drugs whose side effects are considered the most severe. The agency warned patients and caregivers to be alert for these side effects and to stop use of the drug if a patient develops neurological or psychiatric symptoms.

Mefloquine was developed by the United States Army, and it entered the commercial market in 1989. Roche, the brand-name manufacturer, no longer sells Lariam in the United States, but generic versions are available.

For years, the drug was favored by travelers not only because of its effectiveness but also because it could be taken once a week, rather than once a day, said Dr. David O. Freedman, director of the travelers’ clinic at the University of Alabama at Birmingham. As warnings on its label steadily increased in severity over the last decade, Dr. Freedman said that his clinic had shifted to other drugs. Ten to 20 percent of his patients traveling to malaria-prone areas now receive a mefloquine prescription, he said.