Before taking levothyroxine,tell your doctor and pharmacist if you are allergic to levothyroxine, thyroid hormone, any other medications, or any of the ingredients in levothyroxine tablets or capsules. Ask your pharmacist for a list of the ingredients.tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following or those listed in the IMPORTANT WARNING section: amiodarone (Nexterone, Pacerone); androgens such as nandrolone and testosterone (Androderm); certain antacids containing aluminum or magnesium (Maalox, Mylanta, others); anticoagulants ('blood thinners') such as heparin or warfarin (Coumadin, Jantoven); beta-blockers such as metoprolol (Lopressor), propranolol (Inderal, Innopran), or timolol; medications for cancer such as asparaginase, fluorouracil, and mitotane (Lysodren); carbamazepine (Carbatrol, Equetro, Tegretol, or Teril); clofibrate (Atromid); corticosteroids such as dexamethasone; medications for cough and cold symptoms or for weight loss; digoxin (Lanoxin); medications containing estrogen such as hormone replacement therapy or hormonal contraceptives (birth control pills, patches, rings, implants, or injections); furosemide (Lasix); insulin or other medications to treat diabetes; maprotiline; mefenamic acid (Ponstel); methadone (Methadose); niacin; orlistat (Alli, Xenical); phenobarbital; phenytoin (Dilantin, Phenytek); proton pump inhibitors such as esomeprazole (Nexium), lansoprazole (Prevacid), and omeprazole (Prilosec); rifampin (Rifater, Rifamate, Rifadin); sertraline (Zoloft); simethicone (Phazyme, Gas X); sucralfate (Carafate); tamoxifen (Soltamox); tyrosine kinase inhibitors such as cabozantinib (Cometriq) or imatinib (Gleevac); and tricyclic antidepressants such as amitriptyline (Elavil). Many other medications may also interact with levothyroxine, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.if you take calcium carbonate (Tums) or ferrous sulfate (iron supplement), take it at least 4 hours before or 4 hours after you take levothyroxine. If you take cholestyramine (Prevalite), colesevelam (Welchol), colestipol (Colestid), sevelamer (Renvela, Renagel), or sodium polystyrene sulfonate (Kayexalate), take it at least 4 hours after you take levothyroxine.tell your doctor if you have adrenal insufficiency (condition in which the adrenal glands do not produce enough of certain hormones needed for important body functions). Your doctor may tell you not to take levothyroxine.tell your doctor if you have recently received radiation therapy or if you have or have ever had diabetes; hardening of the arteries (atherosclerosis); bleeding problems or anemia; porphyria (condition in which abnormal substances build up in the blood and cause problems with the skin or nervous system); osteoporosis (a condition in which the bones become thin and weak and break easily); pituitary gland (a small gland in the brain) disorders; any condition that makes it difficult for you to swallow; or kidney, heart, or liver disease.tell your doctor if you are pregnant, plan to become pregnant or are breastfeeding. If you become pregnant while taking levothyroxine, call your doctor.if you have surgery, including dental surgery, tell the doctor or dentist that you are taking levothyroxine.