WASHINGTON (AP) — The Food and Drug Administration has alerted physicians to new warnings on anti-seizure drugs about heightened risks of suicidal tendencies, following an earlier announcement that the labels would be required. The labeling applies to more than 20 medications used to control seizures, psychiatric disorders and nerve pain. The warnings caution doctors that there is increased "risk of suicidal thoughts or behavior in patients taking these drugs for any indication." Regulators highlighted the new language in letters sent to physicians, according to a posting Tuesday on FDA's Web site. The FDA announced in December that it would require the warnings. The heightened risk is small. An analysis by FDA concluded that an additional two patients per 1,000 would have suicidal thoughts and behaviors when taking the drugs compared with placebo. Drugs bearing the new language include blockbuster products like GlaxoSmithKline's Lamictal, Johnson & Johnson's Topamax and Pfizer's Lyrica. New York-based Pfizer said it "worked closely with the FDA to update the labeling for its antiepileptic medicines," and noted that the warning "applies to all medicines in the antiepileptic class." The FDA is requiring companies to distribute medication pamphlets to patients about the risks. Regulators approved the medication guides and the new warning labels on April 23, according to the agency's Web site. The FDA did not add its sternest warning to the medications, following the advice of its outside experts. In July a panel of advisers said adding the so-called "black box" warning, the strongest type available, could cause undue alarm among patients and cause them to stop taking their medications. Anti-seizure drugs are used for a variety of illnesses besides epilepsy, including migraines, certain nerve-pain disorders, and mental illnesses such as bipolar disorder. The drugs were the fourth-best-selling class in the U.S. last year with total sales of $11.3 billion, according to industry research firm IMS Health.