Back acne treatment

Do you know where I can get the best treatment for back acne ? I have a friend who has back acne lately, and her problem is how to get rid of it since she will be a bridesmaid soon and will be wearing a low back gown. Concealer will surely not hide evrything, and she doesn't want her back to be an awful sight for the guests. Treatment is really the key here so I am helping her out to get the best one. We still have a month so I hope that the time frame is still feasible. Message me if you happen to know one!