1911 Encyclopædia Britannica/Nettlerash

NETTLERASH, or Urticaria, a disorder of the skin characterized by an eruption resembling the effect produced by the sting of a nettle, namely, raised red or red and white patches occurring in parts or over the whole of the surface of the body and attended with great irritation. It may be acute or chronic. In the former variety the attack often comes on after indulgence in certain articles of diet, particularly various kinds of fruit, shellfish, cheese, pastry, &c., also occasionally from the use of certain drugs, such as henbane, copaiba, cubebs, turpentine, &c. There is at first considerable feverishness and constitutional disturbance, together with sickness and faintness, which either precede or accompany the appearance of the rash. The eruption may appear on any part of the body, but is most common on the face and trunk. The attack may pass off in a few hours, or may last for several days, the eruption continuing to come out in successive patches. The chronic variety lasts with interruptions for a length of time often extending to months or years. This form of the disease occurs independently of errors in diet, and is not attended with the feverish symptoms characterizing the acute attack. As regards treatment, the acute variety generally yields quickly to a purgative and the use of some antacid, such as magnesia or liquor potassae. The local irritation is allayed by sponging with a warm alkaline solution (soda, potash or ammonia), or a solution of acetate of lead, and a lotion of ichthyol has been found useful. Chronic cases have been known to benefit from the administration of creosote or salol.