Brian Link wrote:

Can you prevent cat-acne?

NO! DO NOT use human products like Proactiv on cats!

To treat kitty acne, wash the area affected with warm water and a a
mild soap, rinse well. pat dry and then blot the affected area ONCE
with hydrogen peroxide. Do not rub or squeeze the affected area! If
the acne continues to worsen within a day or so, see your vet.

-L.