ABSTRACT
Chlorproethazine is probably hardly, if at all, used anymore, either orally or topically. In France, before 2001, 10 patients (5 women, 5 men, mean age 65 years) suspected to be allergic to a musclerelaxing ointment containing chlorproethazine have been investigated in 2 hospitals. Patch tests and photopatch tests were also carried out with the related phenothiazines chlorpromazine 0.1% pet. Patch tests were positive in all 10 patients to the ointment (which was irritant) as is and chlorproethazine 10% pet. All 3 patients who were photopatch tested with the ointment and chlorproethazine 10% and 1% pet. Patch tests with the related phenothiazines chlorpromazine and promethazine were negative in all 5 patients tested. However, photopatch tests were positive to chlorpromazine in 4/4 cases and promethazine in 3/4 cases. Contact allergy to chlorproethazine frequently results in photocross-reactions to the related phenothiazines chlorpromazine and promethazine.
