Before taking omeprazole,
tell your doctor and pharmacist if you are allergic to omeprazole, dexlansoprazole (Dexilant), esomeprazole (Nexium), lansoprazole (Prevacid, in Prevpac), pantoprazole (Protonix), rabeprazole (Aciphex), any other medications, or any of the ingredients in the omeprazole product you will be taking. Ask your pharmacist or check the package label for a list of the ingredients.
tell your doctor if you are taking rilpivirine (Edurant, in Complera, Odefsey). Your doctor will probably tell you not to take omeprazole if you are taking this medication.
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: anticoagulants ('blood thinners') such as warfarin (Coumadin), atazanavir (Reyataz), cilostazol (Pletal), citalopram (Celexa), clopidogrel (Plavix), cyclosporine (Gengraf, Neoral, Sandimmune), dasatinib (Sprycel), diazepam (Valium), digoxin (Lanoxicaps, Lanoxin), disulfiram (Antabuse), diuretics ('water pills'), erlotinib (Tarceva), iron supplements, itraconazole (Onmel, Sporonox), ketoconazole (Nizoral), methotrexate (Rheumatrex, Trexall), mycophenolate mofetil (Cellcept), nelfinavir (Viracept), nilotinib (Tasigna), phenytoin (Dilantin), rifampin (Rifadin, in Rifater), St. John's wort, saquinavir (Invirase), tacrolimus (Prograf), and voriconazole (Vfend). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
if you plan to take nonprescription omeprazole, tell your doctor if your heartburn has lasted 3 months or longer, if you have taken nonprescription omeprazole for a longer period of time than stated on the package, or if you have experienced any of the following symptoms: lightheadedness, sweating, or dizziness along with your heartburn; chest pain or shoulder pain; shortness of breath or wheezing; pain that spreads to your arms, neck, or shoulders; unexplained weight loss; nausea; vomiting, especially if the vomit is bloody; stomach pain; difficulty swallowing food or pain when you swallow food; or black or bloody stools. You may have a more serious condition that cannot be treated with nonprescription medication.
tell your doctor if you are of Asian descent and if you have or have ever had a low level of magnesium in your blood low levels of vitamin B-12 in your body, osteoporosis, an autoimmune disease (condition in which the body attacks its own organs, causing swelling and loss of function) such as systemic lupus erythematosus, or liver disease.