Nettle-Rash, or Urticaria, a cutaneous disease, thus denominated, from the resemblance of the eruption to that produced by the stinging of nettles. Numerous pimples appear on the skin, often suddenly after rubbing or scratching it; though they generally vanish in a few hours, and sometimes in a few minutes.
The nettle-rash affects some persons only for one or two hours; others for a few days ; while in some it continues for several months, and even years. It more commonly attacks females than males, and children oftener than adults ; but is not infectious.
The cause of the nettle-rash is ascribed, by Dr. Heberden, to some mechanical object, applied to the skin, such as COWHAGE, or the spiculae of cantharides adhering after the removal of blisters; though the disorder may be induced by eating muscles, lobsters, shrimps, and even honey, as likewise from partaking of fish not sufficiently dressed, or of fresh pork, etc. so that the foundation of it appears to be laid in the organs of digestion, which prepare a coarse chyle, consequently crude and acrid fluids. From whatever cause this affection may arise, Dr. H. conceives that it does not corrupt the humours, so as to require interval remedies : he is of opinion that, if the itching could be speedily mitigated, no farther medicine would be necessary. For this purpose, a mixture of oil, vinegar, and spirit of wine, may be applied to the skin, and will afford a temporary relief ; though Prof. Starck, of Jena, believes this eruption (when it is of a periodical or chronic nature) to originate from a diseased viscus or intestine; and therefore prescribes, first, sudorifics and diuretics, then resolvent and strengthening medicines ; but especially the copious use of Seltzer-water,