Antifibrinolytic drugs are frequently used to prevent blood loss during surgery, but sometimes cause convulsive seizures. In this issue of the Journal of Clinical Investigation, researchers led by Beverly Orser at the University of Toronto investigated the molecular mechanisms that underlie this side effect. By studying antifibrinolytics in mice, Orser and colleagues found that the drugs inhibited the activity of glycine receptors in the brain, leading to seizures. Seizures could be prevented by co-treatment with the general anesthetic isoflurane. This study explains the causes of and proposes treatment for antifibrinolytic-induced seizures. In a companion commentary, Debra Schwinn of the University of Washington reviews the connection between seizures and antifibrinolytic drugs.