###Human: What is the reason for hives? Are these harmful? ###Assistant: Hi. You have urticaria or hives. These medicines are safe, and they can be continued for a while if the problem persists. Hives can happen in response to a food allergen or food preservative, medications, infections, and alcohol. A large number of urticarias are idiopathic. There is no known cause for having it. Urticaria is mainly symptomatic, and it is treated with oral antihistamines.