What is the difference between urticaria and allergic dermatitis?

Urticaria and allergic dermatitis are caused by skin allergy, urticaria can also be caused by drug factors, physical factors, mental factors and infection. The symptoms of the two are also different. In addition to itching and edema, urticaria can appear red or pale wheals. Contact dermatitis is mainly characterized by erythema, papules or blisters.