Common side effects of dimethyl sulfoxide in humans include swelling of the face, difficulty breathing, and swelling of the lips, throat and tongue. Some patients may experience irritation upon initial insertion of the medicine but find that the discomfort declines after several treatments, explains Everyday Health.
DMSO causes a garlic or onion-like taste in the mouth, skin and breath that may last for several hours after taking the medicine, according to Everyday Health. Some patients may experience mild headaches, stomach upset and sensitivity to light. DMSO burns the skin if not properly diluted, notes the University of Michigan Health System. DMSO may cause discomfort when used on the bladder, but the sensation fades with regular use of the medicine, reports Mayo Clinic.