SIDE EFFECTS: Upset stomach or heartburn may occur. If either of these effects lasts or gets worse, tell your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: easy bleeding/bruising, unusual tiredness, signs of kidney problems (such as change in the amount of urine), signs of liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, yellowing eyes/skin, dark urine), symptoms of a low magnesium blood level (such as muscle spasms that don't go away, fast/slow/irregular heartbeat, seizures), signs of lupus (such as rash on nose and cheeks, new or worsening joint pain). This drug may rarely cause serious (rarely fatal) bleeding from the stomach or intestines. If you notice any of the following unlikely but serious side effects, stop taking this medication and consult your doctor or pharmacist right away: stomach/abdominal pain that doesn't go away, black stools, vomit that looks like coffee grounds. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of bacteria. Do not use anti-diarrhea or opioid medications if you have any of the following symptoms because these products may make them worse. Tell your doctor right away if you develop: diarrhea that doesn't stop, abdominal or stomach pain/cramping, fever, blood/mucus in your stool. Rarely, proton pump inhibitors (such as omeprazole) have caused vitamin B-12 deficiency. The risk is increased if they are taken every day for a long time (3 years or longer). Tell your doctor right away if you develop symptoms of vitamin B-12 deficiency (such as unusual weakness, sore tongue, or numbness/tingling of the hands/feet). A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking this medication, tell your doctor if you are allergic to aspirin or omeprazole; or to other salicylates (such as choline salicylate); or to NSAIDs (such as ibuprofen, naproxen); or to other PPIs (such as esomeprazole, lansoprazole); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: aspirin-sensitive asthma (a history of worsening breathing with runny/stuffy nose after taking aspirin or other NSAIDs), bleeding/blood problems (such as hemophilia, vitamin K deficiency), stomach/intestinal/esophagus problems (such as bleeding, heartburn, ulcers), kidney disease, liver disease, growths in the nose (nasal polyps), lupus. This medicine may cause stomach bleeding. Daily use of alcohol and tobacco while using this medicine may increase your risk for stomach bleeding. Limit alcohol and stop smoking. Ask your doctor or pharmacist about how much alcohol you may safely drink. Proton pump inhibitors (such as omeprazole) may increase your risk for bone fractures, especially with longer use, higher doses, and in older adults. Talk with your doctor or pharmacist about ways to prevent bone loss/fracture, such as by taking calcium (such as calcium citrate) and vitamin D supplements. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Your doctor may instruct you to stop this medication before surgery. Do not stop taking it without first talking with your doctor. This drug contains aspirin. Children and teenagers younger than 18 years should not take aspirin if they have chickenpox, flu, or any undiagnosed illness or if they have recently received a vaccine. In these cases, taking aspirin increases the risk of Reye's syndrome, a rare but serious illness. Older adults may be more sensitive to the side effects of this drug, especially bleeding. Aspirin is not recommended for use during pregnancy. This medication should be used only when clearly needed during the first 6 months of pregnancy. Do not use this medication during the last 3 months of pregnancy because of possible harm to the unborn baby or problems during delivery. Discuss the risks and benefits with your doctor. This medication passes into breast milk. Breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: corticosteroids (such as prednisone), methotrexate (especially high-dose treatment), mifepristone, ginkgo biloba, other drugs that can cause bleeding/bruising (including antiplatelet drugs such as clopidogrel, ticagrelor, NSAIDs such as ibuprofen/naproxen, "blood thinners" such as warfarin/dabigatran). Check all prescription and nonprescription medicine labels carefully since many medications contain pain relievers/fever reducers (aspirin, NSAIDs such as ibuprofen or naproxen). These drugs are similar to this medication and may increase your risk of side effects if taken together. Ask your doctor or pharmacist for more details. Some products need stomach acid so that the body can absorb them properly. Omeprazole decreases stomach acid, so it may change how well these products work. Some affected products include atazanavir, erlotinib, nelfinavir, pazopanib, rilpivirine, certain azole antifungals (itraconazole, ketoconazole, posaconazole), among others. Other medications can affect the removal of omeprazole from your body, which may affect how this product works. Examples include rifampin, St John's wort, among others. Omeprazole is very similar to esomeprazole. Do not use any medications containing esomeprazole while using omeprazole. This medication may interfere with certain lab or medical tests, possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: ringing in the ears, flushing, sweating, restlessness, weakness, dizziness, fast heartbeat.