Adult acne, whether constant or cyclical breakouts, can occur at nearly any age. What causes breakouts in adulthood, and what can you do? 1. Hormone imbalances Your hormones are constantly changing. Great skin in your 20's does not predict blemish-free skin in your 30's, 40's, or even 50's. After age 35 hormones start plummeting. Estradiol, progesterone, DHEA, and testosterone all take a dive at different rates, causing imbalances, and relative excesses or deficiencies of one