Skin | Dermatology | Urticaria (Symptom)
Urticaria is a skin disease characterized by edematous skin lesions, defined contours and an erythematous halo, usually fleeting and changing. The rash is accompanied usually by itching. When a person has an allergic reaction to a substance, the body releases histamine and other chemicals into the bloodstream, causing itching, swelling and other symptoms.
Urticaria is a common reaction, especially in people with other allergies like hay fever. When swelling or welts occur around the face, lips and eyes, is called angioedema. Swelling from angioedema can also occur around hands, feet and throat. Many substances can trigger hives, including: Animal dander (especially cats), insect stings, drugs, pollen, shellfish, fish, nuts, eggs, milk and other foods.
Hives are frequently caused by allergic reactions. However, there are many non-allergic causes. Most cases of hives lasting less than six weeks (acute urticaria) are the result of an allergic trigger. Chronic urticaria (hives lasting longer than six weeks) is rarely due to an allergy.