The disease runs on four steps: androgens enlarge the oil glands, the follicle lining stops shedding cleanly and forms a plug, Cutibacterium acnes feeds on the trapped oil, and the immune system inflames the whole thing ¹². Inflammation is there from the start, which is why nothing you do to the surface of the skin fixes it. Acne happens inside the follicle.

What's at stake is the face, and the years around it. Untreated moderate-to-severe acne leaves permanent atrophic scars in roughly one in three teenagers, and picking at the lesions is the biggest driver after severity itself ³. The other half is mental: substantial acne roughly doubles the odds of suicidal thoughts, and an acne diagnosis raises the rate of a new depression diagnosis by 63% the following year ⁴⁵. It lands in the exact years identity and body image consolidate.

The fix is a ladder, and the bottom rung is cheap. Benzoyl peroxide cuts lesion counts about in half by twelve weeks, and the bacteria have never developed resistance to it ¹. Topical retinoids like adapalene normalise how the follicle sheds, so plugs stop forming; adapalene 0.1% is over-the-counter and under $20 a tube. The two together beat either alone. Above them sit oral tetracyclines (capped at three months), hormonal options for females like birth-control pills or spironolactone ⁶⁷, and isotretinoin, which clears 85% of severe acne for good ⁸.

The timeline runs behind the biology. Two weeks in, the cysts hurt less before anything looks different. By six to eight weeks, fewer new spots arrive. Twelve weeks is when you judge it: lesion counts down 40–60% on the combination ¹, and photos stop getting deleted. A year in is the arithmetic that counts: a face that never got inflamed deep enough to scar, carried intact into the twenties.