Hives are not contagious. There are many causes of urticaria, the most common is allergic factors, mostly seen in allergic patients, when contact with allergens, it will cause the body of the skin and mucous membrane parts of the vascular permeability increases, which will cause local skin and mucous membrane edema, causing the symptoms of the change of the air masses.
For this situation, we need to actively carry out anti-allergy therapeutic intervention, for example, you can also use cyproheptadine and other antihistamines, or with vitamin C, as well as calcium gluconate and other therapeutic drugs to reduce vascular permeability. Usually also need to pay special attention to avoid contact with easily allergic substances."