Contact Hypersensitivity to Brilliant Green and Gentian Violet

Patch tests in 215 patients having contact dermatitis due to local antibacterial agents, revealed 18 patients having positive patch tests with 1% aqueous brilliant green and one patient with 1% aqueous gentian violet. Twelve of the patients having positive patch tests with brilliant green were tested again with increasing dilutions of brilliant green to ascertain the titre of contact hypersensitivity (TCH), i. c. the highest dilution or the lowes I t concentration of brilliant green giving a positive patch test in the patient. The vaule of TCH differed widely in different patients, the lowest concentration giving a positive patch test being 0.62% in two patients. Ten patients with positive patch tests were subjected to the usage test which consisted of painting 1% aqueous brilliant green on a normal skin area of the forearm twice daily for seven days. In four patients the usage test was positive.