✔ 最佳答案
Back Acne (Or "bacne" as many affectionately call it) can be caused by hormones, shampoos and conditioners, or sweat.
You can prevent this kind of acne by showering after strenuous activity, and rinsing your hair in the shower to the side instead of letting the shampoo and conditioner run down your back if you have long hair. Loofahs or other scrubby bath tools can also get some of the dead skin up.