How can i treat acne on my back and chest?

Rx: When it is this severe, prescription medicine is the only thing that works. Your physician may consider starting with a combination of topical Clindamycin and either a retinoic acid derivative (likely) or benzoyl peroxide; it's likely it will be necessary to add a systemic antibiotic as tolerated. If the lesions are deep and cystic, dermatologists have the big guns. Good luck.