i see acne on the buttocks very commonly in my practice and invariably i have asked every single patient who has this if they are wearing spandex as their workout gear and they always are so i find that if you just switch what you are wearing to cotton as opposed to spandex there is more breathability and that will help as well. in order to treat the problem i usually recommend a benzoyl peroxide cleanser and a topical clindamycin based antibiotic and also regular exfoliation. that helps clear the problem more quickly. but in order to prevent it try using cotton based fabric against your skin.
i work out and sometimes i get acne breakouts on my butt. i have to wear clothes. so how can i fix this problem?