What are the symptoms of allergic skin reactions?

Allergic skin symptoms mainly include various types of rashes, such as erythema, papules, vesicles, etc., accompanied by varying degrees of itching, stinging, redness, swelling, and other discomforts. These symptoms are commonly seen in allergic skin diseases such as urticaria, eczema, contact dermatitis, drug eruptions, etc. Specific symptoms may vary due to individual differences and severity of the condition, but they usually cause obvious damage to the skin. The typical symptom of urticaria is the appearance of wheals of varying sizes and different shapes on the skin. These wheals are usually accompanied by itching and emerge and fade rapidly. Eczema may manifest as polymorphic rashes, such as erythema, papules, vesicles, etc., and may be accompanied by exudation and crusting. Contact dermatitis typically occurs after exposure to allergens, with symptoms including erythema, edema, papules, etc. In severe cases, vesicles and bullae may also appear.