Dermatitis venenata is an inflammation of the skin of external origin. The external irritant best known to the average layman is poison ivy. There are, however, many hundreds of substances of chemical, animal, or vegetable nature which are capable of producing this type of eruption. The outbreak occurs on exposure to a given irritant if the individual is susceptible to that particular irritant.
Among the most common irritants other than poison ivy are sumac, primrose, hair dyes, dyes used in furs and clothing, and such chemicals as formaldehyde, bichloride of mercury, lysol and other antiseptics, and strong soaps. As mentioned, an important factor in the production of the eruption is susceptibility on the part of the individual. Where one individual can pick sumac and poison ivy and experience no ill effects, another individual will develop an acute skin disorder on the slightest exposure to these agents.
The areas if the skin affected are for the most part those portions directly exposed to the irritant. The eruption occurs most commonly, therefore, on the hands, forearms, face, and neck.
Signs of trouble often appear within a few hours after exposure. The eruption may be merely in the form of redness, scaling, and slight swelling in ill-defined areas, accompanied by rather severe itching and burning sensations. These areas may also be the seat of numerous water blisters and crusted areas resulting therefrom as well as the seat of pimple-like and hive-like lesions. An individual so affected cannot transmit the disorder even by direct contact to one who is unaffected. It is probably, however, that in the case of poison ivy, or some such strong vegetable irritant, the individual can, within the first few hours, spread the eruption on himself.
The important thing with regard to the prophylaxis and treatment of the disorder is the determination of the irritant responsible for it, since the eruption clears up soon after the removal of the cause, that is, within a week or two. The disappearance of the eruption is hastened by the use of the proper local preparations. In the case of poison ivy, treatments can be given which have a specific neutralizing effect on that particular causative agent. In any instance, there is no immunity established, each succeeding attack tending to be more severe than the preceding one. The severity of an attack depends on the length of time the skin is exposed to the irritant as well as on the degree of susceptibility of the individual.
by Clark W. Finnerud
Common Skin Diseases of Children
