What is tret (tretinoin) and how is it different from retinol?

Tretinoin (tret) is a prescription-strength retinoic acid — the active form that skin cells use directly, with no conversion step required. This makes it significantly more potent and faster-acting than over-the-counter retinol, but also more likely to cause the initial dryness, peeling, and irritation known as the retinoid reaction. Tretinoin is available in concentrations from 0.025% to 0.1% and is the gold standard for anti-aging and acne treatment.