Tretinoin

How and why it works

Tretinoin (all-trans retinoic acid) is the most extensively studied topical retinoid with over 50 years of clinical evidence. It binds to all retinoic acid receptors (RAR-α, β, γ), accelerating epidermal cell turnover from ~28 days to ~14 days. This rapid turnover pushes existing comedones to the surface while preventing new ones from forming. In the dermis, tretinoin stimulates collagen I and III synthesis, reduces collagenase activity, and increases glycosaminoglycan production—making it the gold standard for both acne and photoaging.

How to use

Apply a pea-sized amount to clean, dry skin once nightly. Wait 20–30 minutes after cleansing to ensure skin is completely dry (applying to damp skin increases irritation). Start with every third night, increasing to nightly over 4–6 weeks. A "purge" of existing microcomedones is normal during weeks 2–6. Always pair with SPF 30+ during the day. Avoid waxing treated areas.

Formulations

A microemulsion cream that encapsulates Tretinoin in a stable, occlusive vehicle for gradual, sustained release into the epidermis. The formulation uses an oil-in-water base that softens the skin while minimizing the harshness typically associated with retinoids. Emollients and humectants in the base help offset transepidermal water loss, supporting the skin barrier during the retinization phase.

Pairs well with

Hyaluronic acid and ceramide moisturizers (to buffer dryness and peeling), niacinamide (calms inflammation and strengthens barrier), azelaic acid (morning use for pigmentation and gentle exfoliation), and gentle, fragrance-free cleansers. Avoid AHAs, BHAs, benzoyl peroxide, and vitamin C in the same routine step. Consider "sandwiching" method: moisturizer → tretinoin → moisturizer for sensitive skin.