Urticaria is an itchy skin allergy that is characterized by the formation of wheals with pale interiors and well-defined red margins. It can be classified into acute and chronic urticaria, depending upon whether the attack lasts for less than or more than 6 weeks respectively. Each urticarial lesion stays for less than 24 hours. Acute urticaria may occur with or without angioneurotic edema, which is characterized by the sudden development of large, circumscribed, and swollen areas just beneath the skin.
Urticaria is commonly caused due to ingestion of foods like nuts, shellfish, eggs, and certain fruits; insect stings; medicines like aspirin and other non-steroidal anti-inflammatory drugs; contact with cosmetics or toxic chemicals; infections that could be viral, bacterial, fungal, or parasitic; systemic diseases like systemic lupus erythematosis, thyroid disorders, and cancers; and stress. In some cases, the cause remains undetectable.
Chronic urticaria is mostly unknown in origin, but its aggravating factors may be similar to those in acute urticaria. Cholinergic urticaria can be easily identified by its appearance in the form of tiny flesh-colored wheals with surrounding red flare. This is accompanied with an increase in the core body temperature. This type of urticaria is triggered by hot showers and exercise. Contact urticaria is commonly seen in people who are allergic to latex rubber. Such people develop urticaria even when undergoing patch or allergy tests.
Urticarias can also be classified on the basis of their triggering factors. Thus, aquagenic urticaria is caused by exposure to water, adrenergic urticaria is induced by stress, solar urticaria is brought on by ultraviolet radiations, and vibratory urticaria develops as a result of vibrations. Pressure urticaria occurs over the pressurized areas of the body such as the shoulder straps and buttocks. Temperature extremes can also evoke such a response in some individuals and are accordingly referred to as heat or cold urticaria, depending on what aggravates them.
When friction or rubbing the skin produces an urticarial rash, this is known as dermatographism. Vasculitic urticaria is often associated with infections, autoimmune diseases, and drug hypersensitivity. The lesions do not itch, are painful, and last for more than 24 hours. A skin biopsy may have to be done in order to diagnose vasculitic urticaria. Since there are so many types of urticaria and some of them could also be life-threatening, it is always advisable to consult a dermatologist and get investigated to know the cause before getting treated.
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Tags: Adrenergic urticaria, Angioneurotic edema, Aquagenic urticaria, Cancer, Cholinergic urticaria, Cosmetics, Dermatographism, Eggs, Nuts, Pressure urticaria, Shellfish, Skin allergy, Solar urticaria, Stress, Urticaria, Vasculitic urticaria, Vibratory urticaria, Wheals
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