PRECAUTIONS: Before taking clarithromycin, tell your doctor or pharmacist if you are allergic to it; or to other macrolide antibiotics (such as , ); or if you have any other . 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: (including problems with past clarithromycin use), , a certain type of muscle disease ().Clarithromycin may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, ) that need medical attention right away.The risk of QT prolongation may be increased if you have certain medical conditions or are taking other that may cause QT prolongation. Before using clarithromycin, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (, slow heartbeat, QT prolongation in the ), 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 , diarrhea, or vomiting. Talk to your doctor about using clarithromycin safely.Clarithromycin may cause live bacterial vaccines (such as typhoid vaccine) not to work as well. Therefore, do not have any immunizations/ while using this medication without the consent of your doctor.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).Older adults may be more sensitive to the side effects of this drug, especially and QT prolongation (see above).During , 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. . Consumer information about the medication CLARITHROMYCIN - ORAL (Biaxin), includes side effects, drug interactions, recommended dosages, and storage information. Read more about the prescription drug CLARITHROMYCIN - ORAL.. Compare Biaxin vs. Clarithromycin, which is better for uses like: Infection, Lyme and Sinus Infections. Compare head-to-head ratings, side effects, warnings, dosages, interactions and patient reviews. Patients rated Biaxin and Clarithromycin evenly with 2.9/5..