Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Antibiotic-associated colitis: This medication, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated or pseudomembranous colitis. Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, stop taking telithromycin and contact your doctor as soon as possible.
Fainting: This medication may cause fainting, especially in people who are experiencing severe nausea, vomiting, or lightheadedness. If these symptoms occur, avoid driving, operating machinery, or participating in hazardous activities while taking telithromycin. If you faint, stop taking telithromycin and contact your doctor immediately.
Heart conditions: Telithromycin can cause an abnormal heart rhythm and should be avoided by people with certain heart rhythm problems, especially long QT syndrome, congenital QT interval prolongation, and bradycardia (low heart rate). People who have had irregular heart rhythms caused by other medications in the past should avoid taking telithromycin. It should also be avoided by people with low blood potassium or magnesium levels, and by people taking certain medications used to treat irregular heart rhythms (e.g., quinidine, procainamide, amiodarone, sotalol). If you experience an irregular heartbeat, stop taking this medication and contact your doctor.
Kidney problems: People with reduced kidney function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. People with severely reduced kidney function may require lower doses of telithromycin.
Liver problems: Although rare, this medication can cause severe liver problems. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, stop taking telithromycin and contact your doctor immediately.
People with reduced liver function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Vision changes: Telithromycin may cause blurred vision, difficulty focusing, and double vision. These vision changes are usually mild to moderate and usually occur after the first or second dose. They may last for a few hours, may recur, and usually disappear when treatment is finished. People taking telithromycin should be aware of how this medication affects them before driving a vehicle or operating machinery. If vision changes occur, stop taking telithromycin and contact your doctor. Your doctor may suggest taking telithromycin at bedtime.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if telithromycin passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children under 13 years of age.