I have acne all around my mouth and on my chest. Why is that? And how to prevent it?

Acne can be anywhere. Acne can occur any place where hair follicles exist in the skin, but it is mostly on the face, neck, back and chest. You can try to prevent it by avoiding the use of oils and lotions, and by using acne creams, like benzoyl peroxide. Do not touch or squeeze your acne. You may have to visit a dermatologist to get prescription medications like retinoic acid and antibiotics.