Hello, Welcome to healthcare magic. Hormonal changes during puberty has not been reported to cause hives. The most common causes include food changes including food preservatives, food colorants, new medications, infections like upper respiratory tract infections, worm infestation and contact allergens. In most of the cases, especially acute cases, it is difficult to pin point a cause. The hives resolve on their own. He will benefit from taking an antihistamine like benadryl at bedtime for 2 weeks. You could also deworm him with Tablet Albendazole 400 mg once the acute episodes subsides. Hope this helps you. Take care.