Skin & Grooming · Explainer
Retinoids: The One Skincare Active With Real Evidence
Decades of human trials for texture and fine lines. Also the active most likely to make you quit in week two, for reasons that are avoidable.
By Julien Malet, · Updated 2026-09-09
Most of the skincare aisle is optional. Two things are not: sunscreen, and a retinoid. Sunscreen prevents damage; a retinoid is the only widely available topical with a serious evidence base for improving skin you already have.
What they are
Retinoids are vitamin A derivatives. They increase cell turnover, and — the part that matters for ageing — they stimulate collagen production in the dermis. Tretinoin has been studied in humans for decades with consistent results for fine lines, texture and pigmentation.
The ladder, weakest to strongest:
| Form | Strength | Availability | | --- | --- | --- | | Retinyl palmitate / retinyl esters | Weakest | OTC. Largely not worth it. | | Retinol | Moderate | OTC. The sensible starting point. | | Retinaldehyde | Stronger than retinol | OTC. One conversion step from retinoic acid. | | Adapalene (0.1%) | Prescription-strength | OTC in the US (Differin). Well tolerated. | | Tretinoin | Strongest, most studied | Prescription. | | Tazarotene | Strongest | Prescription. |
Everything above converts, in one or more steps, to retinoic acid — the form your skin actually uses. Each conversion step loses potency, which is the whole reason the ladder exists.
Adapalene is the value pick. It went over the counter for acne, it is genuinely prescription-strength, it is more photostable and better tolerated than tretinoin, and it costs very little.
Why people quit
Almost everyone who abandons retinoids does so because of the adjustment period — often called retinisation. For two to six weeks: dryness, flaking, redness, irritation, sometimes an initial breakout.
This is expected and it passes. But most people either apply too much, apply it nightly from day one, or both — and then conclude their skin cannot tolerate retinoids.
The protocol that works
Start twice a week. Not nightly. Increase frequency only when your skin is calm at the current one. Getting to nightly over eight weeks is faster than getting there in one week and stopping.
Use a pea. A pea-sized amount for the entire face. More is not faster; more is just irritation.
Apply to dry skin at night. Retinoids degrade in UV light, so nights only.
Moisturize. Before or after, or both. Sandwiching — moisturizer, retinoid, moisturizer — meaningfully reduces irritation with minimal loss of effect and is the single best tip for sensitive skin.
Sunscreen every morning, non-negotiable. Retinoids thin the stratum corneum initially and increase photosensitivity. Using one without daily sunscreen is working against yourself. What matters in sunscreen.
Give it three months. Turnover changes show in weeks; collagen changes take months. Six months is where the good before-and-afters come from.
What not to combine, and what is fine
The internet overstates this. Broadly:
- Avoid using benzoyl peroxide in the same application as tretinoin — it can oxidise it. Different times of day is fine, and adapalene is stable with benzoyl peroxide.
- Go carefully with AHAs/BHAs and retinoids on the same night, especially while adjusting. Alternate nights.
- Fine: niacinamide, hyaluronic acid, ceramides, most moisturizers. Vitamin C in the morning and a retinoid at night is a standard, sensible pairing.
Who should not
Retinoids are contraindicated in pregnancy and while trying to conceive — oral retinoids are strongly teratogenic and topical use is avoided as a precaution. Talk to your doctor.
If you have eczema, rosacea or very reactive skin, start with adapalene twice a week and the sandwich method, or see a dermatologist.
A complete routine
Morning: cleanse, moisturizer, sunscreen. Night: cleanse, retinoid, moisturizer.
That is it. Anything else is optional and most of it is optional in the sense of being unnecessary.