Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of levothyroxine.
Certain medicines can make levothyroxine less effective if taken at the same time. If you use any of the following drugs, avoid taking them within 4 hours before or 4 hours after you take Euthyrox:
calcium carbonate (Alka-Mints, Caltrate, Os-Cal, Oyster Shell Calcium, Rolaids Soft Chew, Tums, and others);
cholestyramine, colesevelam, colestipol;
ferrous sulfate iron supplement;
sucralfate;
sodium polystyrene sulfonate (Kalexate, Kayexalate, Kionex);
stomach acid reducers - esomeprazole, lansoprazole, omeprazole, rabeprazole, Nexium, Prilosec, Prevacid, Protonix, Zegerid, and others; or
antacid that contain aluminum or magnesium - Gaviscon, Maalox, Milk of Magnesia, Mintox, Mylanta, Pepcid Complete, and others.
Many drugs can interact with levothyroxine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.
 Euthyrox drug interactions (more detail)
