acne medicine and perms

Ii have a client that has had a spiral perm over a year ago. She also has had it streaked twice since then. Once blonde and once reddish. She would like it permed again but I was at a hair show and they informed us that if you are on this acne medication(not sure of the name but it is new) that that hair will go to mush. The lady experienced it herself that was giving the show. My client is on this acne medication . How long does it take before medication is in the hair and would any one advise me to do this perm. My gut reaction is no. Thanks for any input.