Many people using this medicine have not encountered serious side effects. If you do experience serious side effects, you should contact your doctor immediately. Signs of serious side effects include redness, irritation, blisters, or peeling at the site of application. Nausea, vomiting, and ringing in the ears are other side effects that might be experienced. Allergic reactions are rare, however if you suspect an allergic reaction you should seek medical attention immediately. Signs of an allergic reaction include rash, swelling, hives, dizziness, or trouble