What product should I use for acne on my face and back?

To treat acne on the face and back, you can try using over-the-counter benzoyl peroxide. This product should be applied to the affected areas 1 to 2 times a day, starting with once a day for the first week and increasing to twice a day if tolerated. Be cautious as benzoyl peroxide can bleach clothing and bedding, so it's best to change before applying it. For facial cleansing, you can use water 1 to 2 times a day at most. It's also important to apply sunscreen to protect your skin from worsening acne caused by sun exposure.