Why does oily skin cause acne?

Sebum: Your skin produces sebum, which is an oily substance designed to moisturize the skin and hair, keep it waterproof & keep it acidic. Sebum also contains some more waxy & fatty type stuff that can clog the pores. Once sebum is stuck in a pore, skin bacteria can cause infection which leads to inflammation, & that results in the redness, swelling & production of pus we all know and hate as acne.

No easy answer: Exactly why one person gets acne and the next person doesn't is unanswerable at this time. What I do know is that washing oil off your skin won't touch your acne. It's unrelated to diet, hygiene or lifestyle. You can manage your acne; if topical benzoyl peroxide as tolerated hasn't cleared you in two weeks, get with your personal physician who can add something that will work.