Overscrubbing the skin: A gentle cleansing twice a day ??? and especially before bedtime ??? is a far more effective anti-acne tactic than frequent, harsh scrubbings. ???Just as important as understanding what causes adult acne is also knowing what doesn???t,??? Dr. Fox says. ???Stress doesn???t cause acne; however, it can cause the oil glands to overproduce, worsening existing acne conditions.???