Stress does not directly cause acne. However, it does create conditions that increase the likelihood of an acne breakout. In fact, studies have shown that college students are more prone to acne about a month prior to major exams.
Stress triggers the release of cortisol, which is a hormone that stimulates the adrenal glands. This causes the glands to secrete oil. When excess oil accumulates under the skin, it mixes with dead skin cells and causes the pores to clog. The clogged pores become a breeding ground for bacteria, causing the skin to become inflamed and swollen, and eventually leading to the formation of blackheads or whiteheads.