Drugs for epilepsy, bipolar illness and mood problems double the risks of suicidal thoughts and behavior, and patients taking them should be watched for sudden behavioral changes, drug regulators have said.

The increased risks, while double in relative terms, are small. The Food and Drug Administration undertook a combined analysis of 199 clinical trials with 43,892 patients and found 4 suicides and 105 reports of suicidal symptoms among the 27,863 patients who were given the drugs compared to no suicides and 35 reports of suicidal symptoms among the 16,029 patients treated with placebos.

Taken together, the risk of suicidal thoughts and behavior was 0.43 percent for those on drug therapy and 0.22 percent for those given placebos.

These medications are primarily used to help epileptics control seizures and to calm the surges in energy and mood that, along with bouts of depression, characterize bipolar disorder. The drugs, which include Depakote, Lamictal, Topamax, Keppra, Lyrica and Neurontin, are sometimes prescribed for chronic pain and headaches, as well.