Cited skincare — every flag names its source, no upsell.What it does
Tretinoin is the active form of vitamin A. Because the skin doesn't need to convert it (unlike retinol), it's roughly an order of magnitude more potent. Used for acne, photoaging, and pigment irregularities. Available in concentrations from 0.025% to 0.1% (cream, gel, microsphere). Available by prescription in most regions. Initial irritation is more pronounced than retinol; pairing with a moisturizer (sandwich method) helps tolerance.
The evidence, graded
strongNo topical retinoid is recommended in pregnancy. The class covers tretinoin, adapalene, tazarotene, trifarotene, retinol, retinaldehyde, retinyl palmitate and hydroxypinacolone retinoate. Direct human data exist mainly for tretinoin and adapalene. The caution extends to the rest as a class-effect. Data on accidental exposure reassure, but are not strong enough to recommend any retinoid here. Oral isotretinoin is a separate case, with an absolute contraindication.Kaplan 2015 · British Journal of Dermatology ↗ expert consensusAzelaic acid and retinol generally pair well. Azelaic acid's anti-inflammatory effect can offset retinoid irritation, and the two are commonly stacked for acne and post-inflammatory pigmentation.Sieber 2014 · Skin Pharmacology and Physiology ↗ expert consensusFor cosmetic anti-aging purposes, retinoids are not recommended under 18. Teen skin is already producing high collagen and cell turnover, and retinoid use in young people is reserved for treating conditions like acne — not for prevention of aging.Motamedi 2021 · Journal of Cutaneous Medicine and Surgery ↗ emergingOlder tretinoin formulations are partially deactivated by benzoyl peroxide when layered, but newer micro-encapsulated formulations are designed to combine. Some prescriptions intentionally combine them.Martin 1998 · British Journal of Dermatology ↗ emergingL-ascorbic acid is acidic (pH around 3); applied directly with retinol it can cause irritation and may compromise stability of both. Most users do better with vitamin C in the AM and retinol in the PM.Pinnell 2001 · Dermatologic Surgery ↗ emergingNiacinamide may reduce retinol-induced irritation while complementing its anti-aging benefits.Bissett 2002 · Cutis ↗ Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
all-trans retinoic acid, retin-a
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