Many hikers and nature enthusiasts already know to pull up their socks and tuck in their pants to help prevent contracting poison ivy, but an offshoot of the illness actually makes itself much more clearly known and visible. Black-spot poison ivy (also called black dot for its dot-like appearance), termed both for its plant coloring and the way it manifests on human skin, is a rarer cousin to the itchy illness. In addition to keeping an eye out for regular poison ivy plants, also watch for plants that seem lacquered in black or dark brown paint.
Shiny black lesions appear on a person infected with black-spot poison ivy anywhere between six to 72 hours after contraction (24 to 72 hours is the most common). While the spots may look like dirt, a cue pointing to black-spot poison ivy is that the lesions do not wash off and appear to be part of the skin. On occasion, black-spot poison ivy is assumed to be cancerous growths. The lesions fall off after time without scarring.
Black-spot poison ivy starts off with the same features and causal factors as standard poison ivy, occurring when skin comes in contact with urushiol, a factor in plant sap. When urushiol meets a warm and humid climate, it gets oxidized and turns dark brown or black. Plants give away their black-spot secret not just by manifesting actual black spots, but by taking on a shiny, thick, dark lacquered appearance.
According to the ConsultantLive and Pediatric Supersite websites, black-spot poison ivy is much rarer than regular poison ivy. A similar dermatological complaint is possible when people have extended contact with black lacquered furniture, since the plant used to make the furniture lacquer contains the same urushiol.
Treating patients suffering from black-spot poison ivy is similar to treating those with standard poison ivy. The places on the skin with the black-spot lesions are washed and coated with topical corticosteroids for up to two to three weeks. Although topical antihistamines are not recommended, oral antihistamines may be prescribed.