I want to know why is that the next day after I depilate my chest a
rash starts? Its like giant acne that appears. I am using now a
norelco machine that rips off the hairs, its not like when you shave
your face, this machine actually takes the hair from the root. I once
read on the internet that this was an allergy for the first time, but
I have done this 5 times already and keeps appearing. Please let me
know what is this, and how to avoid this problem when I depilate.

Thanks

If by rash you mean little raised red dots where the hairs were, this
happens everytime I have my legs waxed! See if you can get a lotion or
gel designed to be used after hair removal. Maybe something with an
antiseptic in it.