Retinoids are the treatment anchor for photoaged skin — and the ingredient most often abandoned in week two because nobody explained the adjustment phase. This guide fixes that.
The retinoid ladder
| Form | Steps to active form | Status | Notes |
|---|---|---|---|
| Tretinoin | 0 — already retinoic acid | Prescription (US & Canada) | Most studied topical for photoaging; typical creams 0.025%, 0.05%, 0.1% — strength is a clinician decision |
| Retinal (retinaldehyde) | 1 | Cosmetic | Faster conversion than retinol; less long-term trial depth; often pricier |
| Retinol | 2 | Cosmetic | Gentler and slower; brands are not required to disclose % — many do not |
| Retinyl palmitate / propionate blends | 3+ | Cosmetic | Weakest conversion; used for tolerance and marketing; thinnest evidence |
| Adapalene 0.1% | Synthetic retinoid | OTC in the US for acne | Acne data is strong; photoaging data is limited. Do not present it as a proven wrinkle treatment |
Evidence and timeline
Strong for tretinoin Good for retinol Retinoids normalise cell turnover, thicken the epidermis, stimulate fibroblasts to make new collagen, and improve pigment distribution. Small, short, often industry-funded retinol trials suggest a well-formulated retinol can approach tretinoin on some measures — we report that cautiously, exactly as those papers invite. Judge results at 6 months; most photoaging trials run 24 weeks or longer, with gains continuing toward a year.
Starting after 50 — general information, not personal medical advice
Low-and-slow protocol
- Patch test first (see the routine guide) — then start at 2–3 nights a week
- Evening only, on fully dry skin, a pea-sized amount for the whole face
- Sandwich method if sensitive: moisturizer, retinoid, moisturizer
- Keep retinoids off eyelids; go slower — or skip — on a reactive neck
- Do not layer an AHA, strong vitamin C or benzoyl peroxide on the same night while learning tolerance
- Daily SPF is non-negotiable: retinoids increase sun sensitivity, and UV undoes the collagen work
Ready to choose a starting strength? Beginner retinol comparison, with % disclosed.