(Nettle rash; Hives)
Definition. An inflammatory neurosis of the skin, characterized by evanescent, pinkish-white or reddish elevations of an edematous nature, known as wheals, and attended by burning, stinging or itching.
Symptoms. The eruption usually appears without any prodromata, although there may be some slight sensation, such as headache, loss of appetite, lassitude and mild fever for a few days. The eruption comes suddenly as firm, circumscribed, pinkish-white, pea-to bean-size elevations. At first red, they develop and become white in the center, or may even stop at the red stage. These wheals last for a few minutes to a few hours and, upon disappearing, are succeeded by others. They are hard, semisolid, roundish or oblong, or even irregular in shape, and may involve any portion of the cutaneous surface or mucous membranes., Suffocative effects are noticed when the larynx or pharynx is involved. The distribution is general, asymmetric and bilateral. The lesions may be few or many in number. Itching and stinging is pronounced, and the skin is often so sensitive to all sorts of irritation that an artificial crop may be developed by some simple irritation (urticaria factitia), and it is even possible to inscribe words or sentences (dermatographism0 on the back of such a patient with a pointed instrument. The wheals may be very small and inclined to be papular (urticaria papulosa), which is frequently noted in childhood, or the opposite condition may be reached, when large or giant wheals are seen, egg- sized or larger, chiefly situated on the abdomen or buttocks (urticaria gigans, urticaria tuberosa). When hemorrhage occurs after the wheals, the condition is called urticaria hemorrhagica, or if bullae develop, it is known as urticaria bullosa. Urticaria ordinarily runs an acute course, many cases lasting but a few hours, while others subside in a few days to a weeks, although it is possible for a recurrence to cause an extension of months.
Etiology and Pathology. Urticaria may be seen in all countries, at all ages and in both sexes, although most prevalent from early childhood to middle adult life, and slightly more common among females. It may be idiopathic or symptomatic in origin, always admitting the existence of a certain predisposition. The causes of the former variety probably act directly or reflexly on the peripheral vasomotor system of nerves, and embrace a long list of external irritants, such as the bites of insects; contact with certain kinds of shell-fish; with certain kinds of plants, particularly the urtica urens from which the disease derives its name; exposure to cold air, or other climatic influences; the contact of too heavy or too closely worn clothing; mechanical or medicinal applications, or mechanical or surgical traumatisms. In many instances the urticarial eruption is not limited to the site of the irritation or injury, but invades a much larger area.
Symptomatic urticaria is due to equally differing internal conditions, though it is estimate that ninety per cent, arise from disturbances in the alimentary tract, due to overindulgence in, or idiosyncrasy to such articles of food as oysters, lobsters, eggs, pork, sausage, cheese, strawberries, dates, raisins, figs, raspberries, goosberriesm, mushrooms, salads, spinach, pears, oatmeal, beans, onions, almonds, and other nuts; canned fruits, vegetables and potted meats; honey, confectionery, tea, coffee, cocoa, beer, champagne, or other alcoholic beverages. A similar idiosyncrasy to large or small doses of such drugs as quinin, turpentine, chloral, cubebs, copaiva, valeriana, arsenic, opium, hyoscyamus, the salicylates, santonin, the iodids and many of the coat-tar products, may produce wheals. In children, intestinal worms are occasionally the source of an attack. Other diseases which may be preceded, attended, or followed by wheals are asthma, malaria, rheumatism, purpura, pemphigus, prurigo, and the eruptive fevers. Lithermia, renal or genitourinary disorders, pregnancy, dentition, mental emotions, such as anger and disorders, pregnancy, dentition, mental emotion, such as anger and d fear, are some of the other causes which excite its production. When the susceptibility is pronounced the effect is frequently marked from seemingly insignificant cause, thus one strawberry, a bit offish, or a grain of quinin may be sufficient, when swallowed, to induce an extensive attack of urticaria which may recur with each indulgence.