Allergic skin red rash may be caused by atopic dermatitis, contact dermatitis, urticaria and so on.
1. Allergic dermatitis: the allergic body after contact with allergens occur immune reaction, the skin can appear all over the body allergic red rash symptoms. It is related to atopic dermatitis caused by type I allergic reaction, i.e. rapid-onset allergic reaction.
2. Contact dermatitis: skin contact with strong irritant or toxic substances can lead to type IV hypersensitivity reaction, i.e., delayed hypersensitivity reaction causing contact dermatitis, which is manifested as a generalized allergic red rash.
3. Urticaria: Infection, food, drugs, skin contacts can cause urticaria, manifested by redness, erythema, red rashes all over the body.
Allergic rash may also be caused by other reasons, should be promptly to the hospital specialist consultation, testing allergens after a clear diagnosis, under the guidance of the doctor symptomatic treatment, usually try to avoid contact with allergic substances.