In epilepsy, the normal behavior of brain neurons is disturbed. The drug valproic acid appears to help the brain replenish a key chemical, preventing seizures. David Mack/Science Source hide caption

itoggle caption David Mack/Science Source

The schizophrenia drug Risperdal was at the heart of government investigations into improper marketing that stretched back more than a decade. JB Reed/Bloomberg via Getty Images hide caption

itoggle caption JB Reed/Bloomberg via Getty Images

Scans from patients with fungal meningitis show evidence of a stroke (left) and arachnoiditis. New England Journal of Medicine hide caption

itoggle caption New England Journal of Medicine

What's in your neighbor's medicine cabinets may influence overdose risk in the community. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Streptococcus pyogenes shouldn't be taken lightly. Left untreated, an infection with germ can trigger an autoimmune disease that damages the heart. NIAID/Flickr.com hide caption

itoggle caption NIAID/Flickr.com

Drug overdose deaths have more than tripled in the U.S. since 1990. Opioid painkillers like OxyContin are the cause of three-quarters of those deaths. Toby Talbot/Associated Press hide caption

itoggle caption Toby Talbot/Associated Press

The active ingredient in Propecia, a baldness remedy approved by the Food and Drug Administration in 1997, is showing new promise as a way to prevent some prostate cancers. AP hide caption

itoggle caption AP

When dealing with aches and pains, sometimes the best way to get better is to feel better — and fast. Some popular medicines of old favored additives like cocaine. Courtesy of the National Library of Medicine hide caption

itoggle caption Courtesy of the National Library of Medicine