SIDE EFFECTS: Nausea, vomiting, diarrhea, stomach pain/cramping, and loss of appetite may occur. Taking this medication with food may lessen these symptoms. If any of these effects persist or worsen, 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: signs of liver disease (such as persistent nausea/vomiting, yellowing eyes or skin, dark urine, severe stomach/abdominal pain), unusual tiredness, muscle weakness, slurred speech, blurred vision, drooping eyelids, hearing loss. Get medical help right away if you have any very serious side effects, including: severe dizziness, fainting, fast/irregular heartbeat. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool. Do not use anti-diarrhea or opioid medications if you have any of these symptoms because these products may make them worse. Use of this medication for prolonged or repeated periods may result in oral thrush or a new yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge or other new symptoms. 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 erythromycin, tell your doctor or pharmacist if you are allergic to it; or to other macrolide antibiotics (such as azithromycin, clarithromycin); 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: liver disease, kidney disease, a certain type of muscle disease (myasthenia gravis). Erythromycin may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using erythromycin, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death). Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using erythromycin safely. Erythromycin may cause live bacterial vaccines (such as typhoid vaccine) to not work as well. Do not have any immunizations/vaccinations while using this medication unless your doctor tells you to. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Some erythromycin products may contain sodium. Ask your doctor or pharmacist for more information if you are on a salt-restricted diet or if you have a condition such as congestive heart failure that could be worsened by an increase in salt intake. Older adults may be more sensitive to the side effects of this drug, especially hearing loss and QT prolongation (see above). Tell your doctor if you are pregnant before using this medication. This medication passes into breast milk. 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: clindamycin, digoxin. Many drugs besides erythromycin may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, cisapride, pimozide, procainamide, propafenone, quinidine, sotalol, among others. Other medications can affect the removal of erythromycin from your body, which may affect how erythromycin works. Examples include azole antifungals (such as itraconazole, ketoconazole), certain calcium channel blockers (such as diltiazem, verapamil), certain anti-seizure medications (such as carbamazepine, phenytoin), quinupristin-dalfopristin, saquinavir, among others. Erythromycin can slow down the removal of other drugs from your body, which may affect how they work. Examples of affected drugs include bromocriptine, colchicine, certain benzodiazepines (such as midazolam, triazolam), eletriptan, ergot alkaloids (such as ergotamine, dihydroergotamine), certain drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), certain "statin" drugs (such as lovastatin, simvastatin), vinblastine, among others. Although most antibiotics are unlikely to affect hormonal birth control such as pills, patch, or ring, a few antibiotics (such as rifampin, rifabutin) can decrease their effectiveness. This could result in pregnancy. If you use hormonal birth control, ask your doctor or pharmacist for more details. This medication may interfere with certain laboratory tests (urine tests), possibly causing false test results. Make sure laboratory 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.