Blackheads are most likely to form on your face (particularly your nose and chin, but also your cheeks), neck, back, and chest. Oil glands (sebaceous glands) are found throughout your body. They secrete sebum, an oily lubricant that keeps your hair and skin nourished and lustrous. As a result, blackheads might occur on your buttocks, thighs, ears, and armpits, although they are uncommon.