The redness of the skin under the neck, consider the following conditions: 1, urticaria, can be manifested as edematous erythema, wind mass, skin scratching syndrome and other phenomena, accompanied by a certain amount of itching, this disease is mainly due to mental tension, excessive stress, stimulation, or due to a large number of consumption of chicken, duck, goose and dog meat, seafood, large amounts of alcohol and other factors, there may be too cold caused by cold urticaria. 2, allergic Dermatitis, which may be caused by allergies caused by contact with poor quality emollients, or allergies caused by contact with cosmetic or chemical products such as asphalt, gasoline, tar, etc. 3. Psoriasis vulgaris, which is a disease caused by infection, endocrine disorders, metabolic disorders and other factors.