Before taking QUALAQUIN, inform your healthcare professional of: any allergic reaction to chemicals contained in the medication (quinine sulfate, quinidine or mefloquine), any additional allergies, your medical history, especially of previous serious side effects with quinine, family/personal history of a certain enzyme problem, an eye nerve problem (optic neuritis), hearing problems (ringing in the ears), any nerve/muscle disease, heart rhythm problems, liver problems, kidney problems, all the products you use, including prescription, nonprescription, and herbal products