What are Parabens?How do they affect the skin?

A 20year-old young woman has been diagonised as allergic to parabens.She has acne on her face and has been taking treatment to control this.She applies moisturiserand sunsceen.Of late she has developed red rashes,especially around the mouth ,apart from which she has severe itching on her face .Is it because of a medicine called Isoace[not sure about the spelling] which was administered for 6 months?She was asked to apply moisturiser liberally to counter the dryness.She is now really despondent .will her skin become normal?