Acne spots on the back are usually caused by a build-up of sweat, usually from workouts. Acne on the back can also be cystic in nature, according to WebMD. When it's cystic, it is usually caused by the hormone androgen, which is produced in larger quantities during a person's teenage years.
Cystic acne on the back can even be caused by "hormone changes in women brought on by menstrual cycles, pregnancy, menopause, or a condition called polycystic ovary syndrome," says WebMD. There is also a genetic component to this problem.
Cystic acne in particular can be treated through antibiotics, birth control pills, retinoids and other prescription-strength creams, as well as prescription medications like Accutane. The problem is only made worse when people pick at blemishes, as this can actually push the bacteria deeper into the body and spread the infection. Healthy diet, sleep, and exercise can help with acne.
Normal acne on the back can be prevented by showering after exercise, and by wiping down machines used at the gym, especially if they come into contact with a person's back, Men's Fitness magazine notes. This will remove any excess moisture and bacteria on the machine. Back acne can also be prevented by regularly changing bed sheets. Dirty bed sheets hold onto oils, sweat and dead skin cells that can clog pores. It also helps to use sheets made from lighter materials, such as lightweight cotton, notes Men's Fitness.