Podophyllum resin is used to remove venereal warts, but is not as effective
against the common wart. Podophyllum also can be absorbed through the skin
resulting in toxic symptoms such as peripheral neuropathy, blood dyscrasias, and
kidney impairment. Podophyllum can cause teratogenic effects and should not
be used during pregnancy.
Cantharidin (Cantharone, Verr-Canth) is used to remove the common wart, but
can be harmful to the normal skin. Cantharidin is applied topically, allowed to
dry, and covered with a nonporous tape for 24 hours. This treatment is repeated
in a week or two.
DERMATITIS
Dermatitis is a skin eruption that is caused by medications (drug-induced der-
matitis) or by a chemical agent coming in touch with the skin (contact dermatitis).
Drug-induced dermatitis is characterized by skin lesions that can be a rash,
urticaria, papules, vesicles or life-threatening skin eruptions such as erythema
multiforme (red blisters over a large portion of the body) or Stevens-Johnson
syndrome (large blisters in the oral and anogenital mucosa, pharynx, eyes, and
viscera). As a result of having a hypersensitive reaction to a drug, the patient
may form sensitizing lymphocytes.
If the patient received multiple drug therapy, the last drug administered to
the patient may have caused hypersensitivity and skin eruptions. Drug-induced
dermatitis may take a few minutes, several hours, or a day for urticaria (hives)
to appear. Certain drugs such as penicillin are known to cause hypersensitivity.
Other drug-induced dermatitis includes discoid lupus erythematosus (DLE) and
exfoliative dermatitis. Hydralazine hydrochloride (Apresoline), isoniazid (INH),
phenothiazines, anticonvulsants, and antidysrhythmics such as procainamide
(Pronestyl) may cause lupus-like symptoms. If lupus-like symptoms occur, the
drug should be discontinued.
Certain antibacterials and anticonvulsants may cause exfoliative dermatitis,
resulting in erythema of the skin, itching, scaling, and loss of body hair.
Contact dermatitis, also called exogenous dermatitis, is caused by chemical
or plant irritation and is characterized by a skin rash with itching, swelling, blis-
tering, oozing, or scaling at the affected skin sites. The chemical contact may
include cosmetics, cleansing products (soaps and detergents), perfume, clothing,
dyes, and topical drugs. Plant contacts include poison ivy, poison oak, and poi-
son sumac.
Nonpharmacological treatment of contact dermatitis includes avoiding direct
contact with the causative irritant. The patient should use protective gloves and
clothing if the chemical agent is associated with his or her employment.
CHAPTER 20 Skin Disorders^377