The FDA issued a warning that the antiseizure medications levetiracetam (Keppra, Keppra XR, Elepsia XR, Spritam) and clobazam (Onfi, Sympazan) can cause a rare but serious reaction that can be life-threatening if not diagnosed and treated quickly. This reaction is called Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). It may start as a rash but can quickly progress, resulting in injury to internal organs, the need for hospitalization, and even death. Symptoms of DRESS generally start 2 weeks to 8 weeks after starting on the medications, but these symptoms may occur earlier or later. A physical examination, laboratory blood tests, and other evaluations are used to diagnose DRESS. As a result, the FDA is requiring drug manufacturers add warnings about this risk to the prescribing information and patient medication guides for these drugs.