In urticaria, or nettle-rash, the erythematous eruption appears in the form of wheals which produce the most distressing irritation. The com plaint may be acute or chronic, and sometimes continues with varying in tensity for months or even years. In the acute form, nettle-rash is a com mon consequence of indigestion and acidity, and is often excited by special articles of food, such as shell-fish, mushrooms, etc. Insanitary conditions have been said to have an influence in promoting the disorder. Whether this be so or not, the affection is no doubt common in neglected children amongst the poor. In such cases it may, however, be the conse quence of uncleanliness, for in subjects with delicate skins external irrita tion alone will set up the complaint. Thus, the eruption may be produced by pediculi, and is a not uncommon complication of scabies and eczema. In the chronic variety nettle-rash appears to be in many cases a disorder of purely nervous origin ; for the eruption is often quite uninfluenced by modifications of diet, while it yields readily to large doses of quinine, as will be afterwards described.
its common form the rash consists of a number of small elevations which rapidly increase in size and become white in the centre with a red border. These wheals are of various sizes and shapes. The smaller may be of the diameter of a pea ; but the larger may measure one or two inches in breadth and reach a considerable elevation above the surface. Sometimes the spots assume an elongated form like thick streaks ; or, again, may appear as a bright red more or less diffused erythematous. blush. In any case they give rise to a stinging irritation which necessitates repeated frictions for its relief. The itching, however, is increased by the means used to relieve it, and the act of rubbing and scratching the skin produces a fresh crop of spots. The course of each individual wheal is very short, for the spots come and go with great rapid ity. Any part of the body may be affected. The wheals may appear on the face, the hands and feet, the limbs, and the trunk ; and the rash in usually roughly symmetrical. Sometimes the eruption is not limited to.
the skin but affects the mucous membrane as well. Thus, the tongue or throat may suddenly swell up and produce alarming symptoms ; but the swelling subsides again as rapidly as it arose.
In acute urticaria there may be well-marked constitutional symptoms. The rash may be preceded by fever, a furred tongue,•vomiting, a quick, feeble pulse, and in some cases a distressing feeling of prostration. These. symptoms are greatly relieved when the wheals appear. An acute attack of nettle-rash lasts from a few hours to several days. Even in this short. time, it varies much in intensity, and is usually greatly aggravated at. night.
In the chronic form, the disorder continues for months. Its course is always very variable, and is subject to occasional remissions, so that it more resembles a series of acute or sub-acute attacks. In this form the eruption may be confined to certain localities (urticaria conferta), or may be general and affect all parts of the body indiscriminately. The wheals are sometimes mixed up with small papular projections, and the complaint is then called lichen urticatus. Another variety of the chronic complaint is that called by Dr. Sangster urticaria pignientosa. The wheals are here very persistent, and leave yellowish pigmented spots on the skin.
is readily recognised. The characteristic wheals resembling exactly the sting of a nettle, the irritation to which they give rise, and the rapidity with which they come and go, leave no room for hesi tation. The severe constitutional symptoms which sometimes precede the acute attack might conceivably arise from so many causes that no opinion should be hazarded until the eruption appears and explains what was ob scure. The beginning of the exanthemata may be marked by similar phenomena, and the metastasis of mumps to the testicle or breast is occa sionally preceded by like symptoms.