Roche Laboratories pulled its new heart drug Posicor off the market worldwide Monday because it causes potentially dangerous interactions with more than 25 other medications, from antihistamines to antibiotics.

The hundreds of thousands of patients now taking Posicor for high blood pressure or chronic angina, a type of chest pain, should not just stop taking the pills on their own, the Food and Drug Administration warned.Stopping medications can be risky, so the FDA urged patients to promptly call their doctors about getting an alternative therapy.