Do NOT use Nexium if:

• you are allergic to any ingredient in Nexium or to similar medicines (eg, omeprazole)
• you are taking certain HIV protease inhibitors (eg, atazanavir, nelfinavir).

Contact your doctor right away if any of these apply to you.

Some medical conditions may interact with Nexium. Tell your doctor if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement 
• if you have allergies to medicines, foods, or other substances
• if you have liver problems or stomach or bowel cancer.

Some medicines may interact with Nexium. Tell your health care provider if you are taking any other medicines, especially any of the following:

• Voriconazole because it may increase the risk of Nexium's side effects
• Anticoagulants (eg, warfarin), cilostazol, digoxin, or saquinavir because the risk of their side effects may be increased by Nexium.
• Azole antifungals (eg, ketoconazole), clopidogrel, HIV protease inhibitors (eg, atazanavir, nelfinavir), or iron because their effectiveness may be decreased by Nexium.

This may not be a complete list of all interactions that may occur. Ask your health care provider if Nexium may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

Important safety information:

• Nexium may cause dizziness. This effect may be worse if you take it with alcohol or certain medicines. Use Nexium with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
• Contact your doctor if you have any symptoms of a bleeding ulcer, such as black, tarry stools or vomit that looks like coffee grounds, or if you experience throat pain, chest pain, severe stomach pain, or trouble swallowing.
• Nexium may interfere with certain lab tests. Be sure your doctor and lab personnel know you are using Nexium.
• Nexium should be used with extreme caution in children; safety and effectiveness in children have not been confirmed.
• Pregnancy and breast-feeding: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Nexium while you are pregnant. It is not known if Nexium is found in breast milk. Do not breastfeed while using Nexium.

All medicines may cause side effects, but many people have no, or minor, side effects.

Check with your doctor if any of these most common side effects persist or become bothersome:

Constipation; diarrhea; dry mouth; gas; headache; nausea; pain, swelling, or redness at the injection site; stomach pain.

Seek medical attention right away if any of these severe side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue; unusual hoarseness); chest pain; fast heartbeat; fever, chills, or sore throat; red, swollen, blistered, or peeling skin; unusual bruising or bleeding; unusual tiredness.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.