Neck allergy red itching may be solar dermatitis, contact dermatitis, food allergies and other causes. 1. Solar dermatitis: If exposed to ultraviolet radiation, it can cause redness, swelling, heat, pain, itching and other allergic reactions in the neck. 2. Contact dermatitis: If the neck is in contact with allergic substances such as plasters, it can cause the body to undergo an abnormal immune response, resulting in neck allergies and red itching. 3. Food allergy: If you ingest seafood and other allergenic substances, it may cause neck allergy, red itching and other symptoms. It is recommended that people with neck allergies go to the hospital in time, clear and away from the allergens, under the guidance of the doctor for standardized treatment, so as not to delay the condition.