If your breathing gets worse while you are using this medicine, call your doctor right away. If you are pregnant, your name may be listed on a pregnancy registry to track the effects of carbamazepine on the baby. If BETHKIS turns dark, it does not change how well BETHKIS works Beta-adrenergic blocking agents: Flurbiprofen attenuated the hypotensive effect of propranolol but not atenolol (see CLINICAL PHARMACOLOGY, Drug-Drug Interactions).