PRECAUTIONS: Before taking lansoprazole, tell your doctor or pharmacist if you are allergic to it; or to similar drugs (e.g., omeprazole, pantoprazole); or if you have any other allergies. Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, other stomach problems (e.g., tumors). Some symptoms may actually be signs of a more serious condition. Tell your doctor immediately if you have: heartburn combined with lightheadedness/sweating/dizziness, chest pain or shoulder/jaw pain (especially with trouble breathing), pain spreading to arms/neck/shoulders, unexplained weight loss. This medicine contains aspartame. If you have phenylketonuria (PKU) or any other condition where you must restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist regarding the safe use of this medicine. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. It is not known whether this drug passes into breast milk. Breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: This drug should not be used with the following medication because very serious interactions may occur: atazanavir. If you are currently using this medication, tell your doctor or pharmacist before starting lansoprazole. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: cilostazol, theophylline, voriconazole, warfarin. Lansoprazole can decrease the effectiveness of certain drugs which require stomach acid in order to be absorbed. Before using this medication, consult your doctor or pharmacist on how to manage such a potential interaction if you are taking the following drugs: ampicillin, azole antifungals (e.g., ketoconazole, itraconazole), iron supplements. Based on information for similar drugs, lansoprazole may increase the amount of digoxin that is absorbed into your blood. Consult your doctor or pharmacist for details if you also take digoxin. Do not start or stop any medicine without doctor or pharmacist approval.