PRECAUTIONS: Before taking levothyroxine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: overactive thyroid conditions (e.g., thyrotoxicosis), a heart attack (acute myocardial infarction), adrenal gland problems (e.g., uncorrected adrenal insufficiency).