(Non-official.) (Poison Ivy.)

Origin. - The fresh leaves of Rhus radicans'L., a climbing shrub indigenous in Canada and the greater part of the United States westward to the Rocky Mountains.

Description and Properties. - Long-petiolate, trifoliate, the lateral leaflets sessile or nearly so, about 4 inches (10 Cm.) long, obliquely ovate, pointed; the terminal leaflets stalked, ovate or oval, pointed, with a wedge-shaped or rounded base; the leaflets entire and glabrous or variously notched, coarsely toothed or lobed, more or less downy; when dry, papery and brittle; inodorous; taste somewhat astringent and acrid. The fresh leaves abound in an acrid juice which darkens on exposure to air, and when applied to the skin produces inflammation and swelling. The leaves should therefore not be touched with the bare hands.

The fresh leaves contain a volatile principle termed toxicodendrol by Pfaff. In addition to this active constituent the leaves contain tannin.

Dose. - 1-5 grains (0.06-0.3 Gm.).

Physiological Action. - Externally and Locally. - The fresh leaves of this common plant are extremely irritant to the skin, generally acting as a marked vesicant and establishing severe local inflammation, manifested by acute dermatitis, excessive edema, and hyperemia. In many cases these effects are much less pronounced, while in certain individuals they are never occasioned by contact with or even chewing the leaves. As with poison sumach - Rhus venenata - the toxic influence of the plant derived from local application is apparently more virulent during the period of flowering.

The inflammation somewhat resembles erysipelas, being rapidly diffused and accompanied by a general systemic disturbance, including abdominal pains, nausea, and vomiting, with perhaps diarrhea, diuresis, and serous passages. Profuse diaphoresis and lumbar and articular pains may also result. These symptoms cease after about ten days or a fortnight without other sequel than desquamation of the affected surface.

Internally. - The effects of the drug administered internally are to cause gastro-intestinal inflammation, with drowsiness and stupor, and occasionally delirium and convulsions. Vertigo, nausea, chilliness, thirst, weak and irregular cardiac movements, diaphoresis, muscular debility, and diuresis are also reported.

Treatment of Poisoning. - Many remedies have been used, with varying efficacy, to allay the toxic effect of the drug. Dermal poisoning has been relieved by glycerite of carbolic acid or alkaline lotions. In the earlier stage of external irritation warm soapsuds and sodium bicarbonate have been successfully applied. Alum-curd, ammonia in a weak solution, solution of chlorinated soda, and many other agents have been employed to meet the requirements of certain stages of the affection. Orthoform or anesthesin in an ointment base, as oxide of zinc, is a useful analgesic.

Therapeutics. - Externally and Locally. - The diluted tincture - 8 minims (0.5 Cc.) to 4 ounces (118 Cc.) of water - has met with some favor in the treatment of sprains, burns, etc.

In weak solution with alcohol the remedy has been used as a stimulating application in cases of sprains, chilblains, burns, insect-stings, etc.

Internally. - It has been recommended in so many affections that it is highly doubtful if it is valuable for any.

The drug is in need of much more thorough investigation, there being widely diverse opinions regarding its therapeutic value. There is, however, sufficient testimony in its favor from competent authorities to justify further examination and use of this extremely active remedy.

Contraindications. - The meager knowledge we possess respecting its true action in disease renders it impossible to mention any special contraindication to its employment.

Administration. - The tincture is the only preparation used, and should be cautiously administered.