Hello, Burning, itching, dryness, redness, skin peeling may occur. However you have been using for 6 years so having such reactions is ruled out.If any of these effects develop or worsen, notify your doctor . Many people using this medication do not have serious side effects.small percentage of it may be absorbed into your bloodstream and may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a resistant bacteria. This condition may occur while receiving treatment or months later. Tell your doctor immediately if you develop persistent diarrhea, abdominal or stomach pain/cramping, or blood/mucus in your stool.A very serious allergic reaction to this drug is unlikely. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. Takecare