SIDE EFFECTS: Nausea, vomiting, diarrhea/loose stools, stomach pain, or pain/redness at the injection site may occur. 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: hearing changes (such as ringing in the ears, hearing loss), persistent nausea/vomiting, severe abdominal/stomach pain, unusual weakness/tiredness, dark urine, yellowing skin/eyes, muscle weakness. Get medical help right away if any of these rare but very serious side effects occur: severe dizziness, fainting, fast/irregular heartbeat. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Do not use anti-diarrhea or opioid medications if you have the following symptoms because these products may make them worse. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool. Use of this medication for prolonged or repeated periods may result in oral thrush or a new vaginal yeast infection. Contact your doctor if you notice white patches/sores in your mouth, a change in vaginal discharge, or other new symptoms. A very serious allergic reaction to this drug is rare. However, seek immediate medical attention 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 using erythromycin, tell your doctor or pharmacist if you are allergic to it; or to any other macrolide/ketolide antibiotics (e.g., clarithromycin, azithromycin); 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: kidney disease, liver disease, a certain type of muscle disease (myasthenia gravis). 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. 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. Caution is advised when this drug is used in infants. Though very unlikely to occur, there have been rare reports of a stomach problem called IHPS (infantile hypertrophic pyloric stenosis) in infants receiving this medication. Contact your child's doctor right away if the child has persistent vomiting or increased irritability. Older adults may be more sensitive to the side effects of this drug, especially hearing loss and QT prolongation (see above). During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor. 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, colchicine, eletriptan, ergot alkaloids (such as ergotamine, dihydroergotamine), digoxin, certain drugs for seizures (anti-convulsants such as carbamazepine, phenytoin, valproate), warfarin. Many drugs besides erythromycin and those listed above may affect the heart rhythm (QT prolongation), including amiodarone, cisapride, disopyramide, dofetilide, gatifloxacin, moxifloxacin, pimozide, procainamide, propafenone, quinidine, sotalol, and thioridazine, among others. Therefore, before using erythromycin, report all medications you are currently using to your doctor or pharmacist. This drug can slow down the removal of other drugs from your body by affecting certain liver enzymes. Some examples of these affected drugs include alfentanil, bromocriptine, buspirone, certain benzodiazepines (alprazolam, midazolam, triazolam), caffeine-containing drugs, cilostazol, corticosteroids (e.g., prednisone), eplerenone, certain drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), eszopiclone, felodipine, hexobarbital, certain "statin" drugs (such as lovastatin, simvastatin), quetiapine, tacrolimus, tolterodine, vinblastine. Other medications can affect the removal of erythromycin from your body, which may affect how erythromycin works. Examples include azole antifungals (such as itraconazole, fluconazole), rifamycins (such as rifabutin), quinupristin-dalfopristin, saquinavir, calcium channel blockers (such as diltiazem, verapamil), 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 (including urinary catecholamines), 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.