Do NOT use Omnicef if:

• you are allergic to any ingredient in Omnicef or any other cephalosporin antibiotic (eg, cephalexin)
• you will be receiving or have recently received a live typhoid vaccine.

Contact your doctor or health care provider right away if any of these apply to you.

Some medical conditions may interact with Omnicef. Tell your doctor or pharmacist 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 had a severe allergic reaction (eg, severe rash, hives, difficulty breathing, dizziness) to a penicillin (eg, amoxicillin) or other beta-lactam antibiotic (eg, imipenem)
• if you have a blood clotting disorder, kidney problems, seizures, diabetes, or stomach or bowel problems (eg, inflammation).

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

• Probenecid because it may increase the risk of Omnicef's side effects
• Live typhoid vaccine because its effectiveness may be decreased by Omnicef.

This may not be a complete list of all interactions that may occur. Ask your health care provider if Omnicef 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:

• Omnicef may cause drowsiness or dizziness. These effects may be worse if you take it with alcohol or certain medicines. Use Omnicef with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
• Omnicef only works against bacteria; it does not treat viral infections (eg, the common cold).
• Be sure to use Omnicef for the full course of treatment. If you do not, the medicine may not clear up your infection completely. The bacteria could also become less sensitive to this or other medicines. This could make the infection harder to treat in the future.
• Long-term or repeated use of Omnicef may cause a second infection. Tell your doctor if signs of a second infection occur. Your medicine may need to be changed to treat this.
• Contact your doctor right away if stomach pain or cramps, severe diarrhea, or bloody stools occur. Do not treat diarrhea without first checking with your doctor.
• If you are taking Omnicef and a product that contains iron, your stools may turn a reddish color. This is normal and not a cause for concern.
• Diabetes patients - Omnicef may cause the results of some tests for urine ketones or glucose to be wrong. Ask your doctor before you change your diet or the dose of your diabetes medicine.
• Omnicef may interfere with certain lab tests (eg, Coomb tests). Be sure your doctor and lab personnel know you are using Omnicef.
• Use Omnicef with extreme caution in children younger 10 years old who have diarrhea or an infection of the stomach or bowel.
• Omnicef should be used with extreme caution in children younger than 6 months old; safety and effectiveness in these 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 Omnicef while you are pregnant. It is not known if Omnicef is found in breast milk. If you are or will be breast-feeding while you using Omnicef, check with your doctor. Discuss any possible risks to your baby.

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:

Diarrhea; headache; nausea.

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); bloody stools; change in the amount of urine produced; dark urine; fever, chills, or sore throat; red, swollen, blistered, or peeling skin; seizures; severe diarrhea or vomiting; severe stomach pain or cramps; unusual bleeding or bruising; vaginal irritation or discharge; yellowing of the skin or eyes.

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.