SIDE EFFECTS: Nausea, vomiting, mild diarrhea, headache, anxiety, or a strange taste in the mouth 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 any of these unlikely but serious side effects occur: vision changes (e.g., blurred/double vision, difficulty focusing). Seek immediate medical attention if any of these rare but serious side effects occur: dizziness, fainting, irregular/fast heartbeat, worsening muscle weakness. Telithromycin may rarely cause very serious liver disease. Seek immediate medical attention if you develop: extreme tiredness, loss of appetite, stomach/abdominal pain, dark urine, yellowing eyes/skin. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to resistant bacteria. This condition may occur 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, or 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 (oral or vaginal fungal 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, seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: 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 telithromycin, tell your doctor or pharmacist if you are allergic to it; or to macrolide antibiotics (e.g., azithromycin, clarithromycin, dirithromycin, erythromycin); 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: myasthenia gravis, kidney disease (including dialysis), liver problems (such as hepatitis, especially if it occurred while taking telithromycin or a macrolide antibiotic). Telithromycin 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. Telithromycin 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 telithromycin, 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 telithromycin safely. This drug may make you dizzy or cause fainting or vision problems. Alcohol or marijuana can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above). During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor. It is not known whether this drug 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, ergot drugs (e.g., dihydroergotamine, ergotamine), ivabradine, metoprolol, certain "statin" drugs for high cholesterol (atorvastatin, lovastatin, simvastatin), warfarin. Telithromycin can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include colchicine, eletriptan, eplerenone, lurasidone, midazolam, regorafenib, rilpivirine, sildenafil, simeprevir, tacrolimus, ticagrelor, triazolam, among others. Other medications can affect the removal of telithromycin from your body, which may affect how telithromycin works. Examples include certain azole antifungals (such as itraconazole, ketoconazole), rifamycins (such as rifampin, rifabutin), St. John's wort, drugs used to treat seizures (such as carbamazepine, phenytoin), among others. Many drugs besides telithromycin may affect the heart rhythm (QT prolongation), including amiodarone, cisapride, dofetilide, pimozide, procainamide, quinidine, sotalol, macrolide antibiotics (such as erythromycin), among others. Therefore, before using telithromycin, report all medications you are currently using to your doctor or pharmacist. 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.

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. Symptoms of overdose may include: irregular/fast heartbeat, fainting.