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: anti-seizure drugs (e.g., carbamazepine, phenobarbital, phenytoin), digoxin, ergot drugs (e.g., dihydroergotamine, ergotamine), ivabradine, live bacterial vaccines (e.g., typhoid or cholera vaccines), metoprolol, rifampin, certain "statin" drugs for high cholesterol (atorvastatin, lovastatin, simvastatin), St John's wort, theophylline, warfarin, drugs removed from your system by certain liver enzymes (such as colchicine, cyclosporine, eletriptan, eplerenone, lurasidone, midazolam, regorafenib, rilpivirine, sildenafil, sirolimus, tacrolimus, ticagrelor, triazolam).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 probably do not affect hormonal birth control such as pills, patch, or ring, some antibiotics may decrease their effectiveness. This could cause pregnancy. Examples include rifamycins such as rifampin or rifabutin. Be sure to ask your doctor or pharmacist if you should use additional reliable birth control methods while using this antibiotic.