Before you start taking VYTORIN, tell your doctor if you have unexplained muscle pain, tenderness, or weakness while taking VYTORIN. Muscle problems, including muscle breakdown, can be serious in some people and rarely cause kidney damage that can lead to death. The risk of muscle breakdown is greater at higher doses of VYTORIN and in patients 65 years of age and older, females, and people with kidney or thyroid problems. The following drugs can increase your risk of serious muscle problems if you take them together with VYTORIN. These drugs should not be used while you are taking this medication: cyclosporine (Gengraf, Neoral, Sandimmune), danazol (Danocrine), gemfibrozil (Lopid), nefazodone (an antidepressant), the antibiotics clarithromycin (Biaxin), erythromycin (E.E.S., EryPed, Ery-Tab, Erythrocin, Pediazole), and telithromycin (Ketek), the antifungal medications itraconazole (Sporanox), ketoconazole (Nizoral), and posaconazole (Noxafil), the HIV/AIDS medications atazanavir (Reyataz), darunavir (Prezista), fosamprenavir (Lexiva), nelfinavir (Viracept), ritonavir (Norvir, Kaletra), saquinavir (Invirase), and tipranavir (Aptivus) amiodarone (Cordarone, Pacerone), amlodipine (Norvasc, Caduet, Exforge, Lotrel, Tekamlo, Tribenzor, Twynsta, Amturnide), diltiazem (Cartia, Cardizem), ranolazine (Ranexa), verapamil (Calan, Covera, Isoptin, Verelan) drink substantial quantities of alcohol, have had liver problems, are pregnant, plan to become pregnant or suspect that you are pregnant, are breast-feeding