The U.S. Food and Drug Administration issued an allergy warning Thursday regarding a popular antipsychotic drug. According to Reuters, serious allergic reactions have been reported following the use of Merck & Co. Incs antipsychotic Saphris.

The agency reported that the label for the drug has since been revised to include information on the risk, but doctors should still look out for allergic reactions in patients taking the drug. Common reactions include anaphylaxis, swelling, low blood pressure and swollen tongue, an FDA notice said.

AboutLawsuits.com reported that there have been at least 52 cases of allergic reaction to the drug filed with the FDA. Nineteen of those cases resulted in hospitalization or emergency room visits, and seven patients required therapeutic interventions.

According to Reuters, the revised warning means that Saphris should not be used in patients with a known hypersensitivity to the drug. If any signs and symptoms of an allergic reaction develop while taking the drug, emergency medical attention should be sought.

Saphris was first approved in August 2009, developed by Merck & Co. to treat symptoms of schizophrenia and bipolar disorder. According to AboutLawsuits, the drug has since been prescribed about 235,000 times to 87,000 patients in the United States.