Nearly 2 dozen cases of a rare but serious skin reaction linked over the past 20 years with the antipsychotic medication olanzapine have prompted a warning from the FDA.

The agency will add information to drug labels for all olanzapine-containing products warning that they may cause drug reaction with eosinophilia and systemic symptoms (DRESS), which can start as a rash that sometimes spreads across the entire body. Fever, swollen lymph nodes, and a swollen face may accompany the rash. The condition results in a higher-than-normal number of eosinophils that can cause inflammation or swelling. In severe cases, damage to organs including the liver, kidneys, lungs, heart, or pancreas may occur.