Which factors are responsible for urticaria?

Urticaria, also known as hives, is a skin rash with red itchy bumps as a result of allergic reactions in the body. It can be caused due to an allergic reaction and the triggers include emotional stress, certain medications, infection, sunlight, food (such as nuts), dust, fabric texture, and certain metals. Allergy is a common cause of urticaria. It is caused when the immune system responds abnormally to an otherwise harmless substance and floods the body with an inflammatory chemical known as histamine. There are two allergies frequently associated with urticaria: food allergies (most commonly nuts, shellfish, milk, eggs, wheat, and soy) and drug allergies (including those triggered by certain antibiotics like cefaclor, anticonvulsants, antifungals like clotrimazole, ibuprofen or sulfonamides).

Physical urticaria is a subset of hives in which the skin rash is provoked by specific environmental or physical stimuli such as cold, heat, pressure, vibration, friction, and sunlight. While the cause of physical urticaria is unknown, it is believed to be an autoimmune response in which the body’s cells attack otherwise normal tissues.