Pimples on the back, also known as bacne, are a common skin condition that can be caused by a number of factors. The most common cause of bacne is excess oil production. When the sebaceous glands in the skin produce too much oil, it can clog pores and lead to bacteria growth. This can result in inflammation and the formation of pimples. Other causes of bacne include poor hygiene, tight clothing that doesn't allow the skin to breathe, and certain medications. Treatment for bacne typically involves topical creams or gels containing benzoyl peroxide or salicylic acid. In severe cases, oral antibiotics may be necessary.