Tell your doctor if any of the following side effects become severe or don't go away: 1  Mild itching, burning, stinging, or tingling skin. 2  Redness or soreness. 3  Increased sensitivity to hot or cold temperatures. 4  Acne. 5  Muscle or back pain. 6  Headache. 7  Flu-like symptoms. 8  Runny or stuffy nose. 9  Nausea.