Do not use Erythromycin if:

• you are allergic to any ingredient in Erythromycin;
• you are taking astemizole, cisapride, cyclosporine, diltiazem, dofetilide, ergot alkaloids (e.g., ergotamine), HIV protease inhibitors (e.g., ritonavir), imidazoles (e.g., ketoconazole), pimozide, QT prolonging agents (e.g., quinidine, sotalol), quinolones (e.g., ciprofloxacin), streptogramins (e.g., quinupristin/dalfopristin), sumatriptan, terfenadine, or verapamil.

• Mild diarrhea is common with antibiotic use. However, a more serious form of diarrhea (pseudomembranous colitis) may rarely occur. This may develop while you use the antibiotic or within several months after you stop using it. 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.
• Erythromycin only works against bacteria; it does not treat viral infections (e.g., the common cold).
• Be sure to use Erythromycin 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 Erythromycin 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.
• Lab tests, including liver function, kidney function, and complete blood cell counts, may be performed while you use Erythromycin . These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
• Pregnancy and breast-feeding: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Erythromycin while you are pregnant. Erythromycin is found in breast milk. If you are or will be breast-feeding while you use Erythromycin, check with your doctor. Discuss any possible risks to your baby.

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

• diarrhea; loss of appetite; nausea; stomach pain; vomiting.

• severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; hearing changes; irregular heartbeat; red, swollen, or blistered skin; severe diarrhea; severe stomach pain or cramps; yellowing of skin or eyes.

Erythromycin is to be used only by the patient for whom it is prescribed. Do not share it with other people.
If your symptoms do not improve or if they become worse, check with your doctor.