The literature is reviewed for contact dermititis associated with transdermaltherapeutic systems. Clonidine. nitroglycern. scopolamine. estradiol and testosterone are utilized in such applications, and fentunyl is under investigation, Most cutaneous reactions are limited to localized dermatitis; however, generalized systemic effects may occur Investigators are reporting skin‐related side‐effects in up to 50% of patients using transdermal clonidine: however, with the other agents, this is much less frequently. Reactivation of the dermatitis via oral medication, fallowing to the patch, is noted in rare instan