Washington - Makers of epilepsy drugs must add a warning that the medicines carry a risk of suicidal thoughts or actions, U.S. health officials said on Tuesday.

The companies also must develop a patient-friendly guide explaining risks, the Food and Drug Administration (FDA) said.

Analysis of 199 clinical trials of 11 anti-epileptic drugs found twice the risk of suicidal behavior or thoughts with the drugs compared to a placebo, the FDA said.

The increase represented about one additional case of suicidal thinking or behavior for every 530 patients treated with one of the medicines, the FDA said.

"The risk of suicidal thoughts or behavior was generally consistent among the eleven drugs analyzed and was observed in patients who were treated for epilepsy, psychiatric disorders, and other conditions," the agency said.

Epilepsy drugs include Pfizer Inc's Lyrica and Neurontin, GlaxoSmithKline PLC's Lamictal and Johnson & Johnson's Topamax.

Glaxo believes the findings of the FDA analysis should be added to the labels of epilepsy drugs, company spokeswoman Sarah Alspach said, adding Glaxo would review the FDA action.

Topamax already includes information about suicidal behavior in its prescribing instructions, said Tricia Geoghegan, a spokeswoman for J&J unit Ortho-McNeil Neurologics Inc. "We will continue to work with the FDA to make sure any changes they request are in there," she said.

A Pfizer spokesman had no immediate comment.