Tagamet (Cimetidine): Side Effects, Interactions, Warning ...
Stop using cimetidine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects: cough, fever, chest congestion, trouble breathing; red or blistering skin rash;