I have had this reaction every single time since I started tirz last year. Have used 3 different suppliers and use either sterile water or bac water from medical supply. My friend is on name brand thru her doctor and also has the same reaction every time. According to her doc, some people just have an allergic or immune system reaction to the drugs and nothing you can do to avoid it. The only thing that I have found that helps for the itching is a cold compress. It usually heals within a few days.