Hi. It must be noted that food maybe only one causative factor in your chronic urticaria, the other important ones being medicines, and environment. Other factors such as pressure, sweat and stress, temperature variation need to be ruled out. Sometimes the cause may not be elicited and a variety known as autoimmune urticaria does exist. Either way see to it that the antihistamine dose is adequate (may need to step it up if hives not controlled) or the need to add another non-sedating antihistamine may be required from another group. Of course that's best decided by the dermatologist. I advise not to take "on and off" treatment. Rather, one should take a daily dose of prescribed and suitable antihistamine preferably for at least 6 weeks and ideally 3 months. Don't miss a single day without the tablets. U can Follow up with me on private chat thereafter. Regards, Dr. Zubin Mandlewala