Severe diarrhea secondary to propranolol.

Although propranolaol is effective and widely used for many disorders, there are reports of it causing side effects severe enough to warrant its discontinuance. A 71-year-old female is reported to have experienced diarrhea and weight loss from the use of propranolol 20 mg qid. On discontinuing the drug, the diarrhea quickly resolved. On rechallenge with 10 mg qid the patient displayed no problems; however, when the dosage was increased to 20 mg qid, the diarrhea returned. When the drug was discontinued the second time, the diarrhea stopped again. The occurrence of diarrhea in any patient receiving propranolol should cause consideration of an adverse drug reaction.