Tretinoin microsphere 0.04% is a controlled‑release retinoid gel for acne that normalizes follicular keratinization, prevents microcomedones, and speeds lesion turnover, using microsponge technology to deliver tretinoin gradually for improved tolerability versus conventional formulations. Apply a pea‑sized amount to clean, dry skin once nightly, easing in with alternate‑night use and pairing with moisturizer and daily broad‑spectrum sunscreen; early dryness or purging usually settles as skin adapts over weeks. Expect noticeable improvement by 8–12 weeks of consistent use, with continued gains thereafter, under routine dermatology follow‑up.