I had cosmelan done at my dermatologist's recommendation for some minor pigmentation about 8 years ago. Her nurse whispered to me before I left to leave it on longer for a better result. Well, I did, and I turned red and peeled like crazy for about a week (which I think is normal).
This peel is no joke - if you do it give yourself a week off from wor, you won't want to be seen in public. I was so raw afterwards I had to wait a bit before starting with the part 2 cream stuff.
At first it seemed like it had worked, but then all the pigmentation returned, plus some extra. And it left my skin absolutely full of blackheads (I guess it brought everything to the surface?) and made my pores look really enlarged. This was all pretty devastating to me at the time. Possibly the worst part was the sort of shrugged off response I received from my derm.
Thank God the pigmentation faded pretty much completely over time, although it took a number of years. I have heard of other people having a similar reaction - I think it was just too harsh for my skin. BTW, I am half hispanic, half caucasian and fair skinned, not sure if that had anything to do with my result.