dietary supplementation
"The Hair, Skin & Nails product I bought has PABA in it.  After several days of taking this multivitamin, I thought my hair was looking better, but I developed an itchy rash all over my torso (mostly on my back).  I don't know whether to attribute this problem to the vitamins (and PABA in particular), but since I've stopped taking the vitamins, the rash seems to be healing."