Retinol has more peer-reviewed evidence supporting its efficacy than almost any other over-the-counter skincare ingredient. It's also the most common source of skin irritation in skincare routines. Understanding the difference between types of retinoids — and how to introduce them — determines whether you get the benefits or just the side effects.
Retinoids are vitamin A derivatives. They work by binding to retinoic acid receptors (RARs) in the nucleus of skin cells, which directly alters gene expression. The effects this produces are well-documented:
Critically, retinol itself is not biologically active. It must be converted by skin enzymes — first to retinaldehyde, then to retinoic acid — which is the active form that binds receptors. This conversion process is what makes OTC retinol gentler than prescription tretinoin (retinoic acid), but also slower.
Different retinoids vary in potency and the number of conversion steps required. More conversion steps = gentler and slower.
OTC retinol products in Canada typically range from 0.025% to 1%. Clinical evidence shows benefit starting at around 0.04–0.1% with consistent use. Products above 1% are available but offer diminishing returns in terms of efficacy-to-irritation ratio for most people — the conversion pathway becomes the limiting factor.
Start at 0.025–0.05% if you're sensitive. Move up slowly over 2–3 months once tolerance is established. A "retinol sandwich" approach (apply moisturizer, then retinol, then moisturizer) can reduce initial irritation significantly.
Pregnancy: All forms of retinoids — including OTC retinol — are contraindicated during pregnancy. Vitamin A derivatives are teratogenic at high systemic doses, and topical retinoids are absorbed systemically. Health Canada and dermatologists universally recommend avoiding them throughout pregnancy and breastfeeding.
SkinCompass reads the full ingredient list — see exactly what retinoid and what concentration you're getting.