Hello, I can understand your concern for hives and allergic reaction to the adhesive on a nicotine patch. Urticaria is a common condition caused by bursting of allergy producing cells known as mast cells due to certain aggravating factors present in the environment. As the chemical inside them is released it produces a rash which you have mentioned. There can be multiple factors producing this condition which are included in day to day life and some times it is really difficult to find one exact cause. The long term effective treatment for this is by oral anti histamine like loratadine or benadryl under medical advise. If I were your dermatologist then would have suggested to take 50 mg every 6 or 8 hours of period. Be cautious about the sedation. All the best.