The skincare aisle contains a great many ingredients with plausible-sounding mechanisms and limited clinical evidence. Retinoids are among the few exceptions, with decades of research behind them.
What they are
Retinoids are compounds derived from or related to vitamin A. They act on receptors in skin cells, influencing gene expression, cell turnover and collagen production.
Several forms exist and they differ in potency and in how many conversion steps they require in the skin.
Prescription retinoids — tretinoin and others — are the active form and act directly. The strongest evidence and the strongest irritation.
Retinaldehyde requires one conversion step. Available over the counter in some regions, less irritating, less potent.
Retinol requires two conversion steps. The most common over-the-counter form.
Retinyl esters require further conversion and are the mildest and weakest.
Adapalene is a synthetic retinoid available without prescription in several markets, developed for acne and generally better tolerated.
Potency generally tracks with irritation, which is the central trade-off.
What the evidence supports
Acne. Topical retinoids are a first-line treatment in essentially every clinical guideline, based on substantial trial evidence. They address comedone formation, which is the underlying process, rather than just treating existing lesions.
Photoageing. Tretinoin has randomised trial evidence for improving fine wrinkles, roughness and pigmentation associated with sun damage. This is one of the few areas in cosmetic dermatology with genuine trial support.
Pigmentation. Evidence for improving uneven pigmentation, frequently used alongside other agents.
Over-the-counter forms have less direct evidence and are generally assumed to work similarly at lower potency, which is a reasonable inference and not the same as demonstrated equivalence.
Why people give up
The retinisation period. Starting a retinoid typically causes redness, dryness, flaking and sometimes increased sensitivity for several weeks.
Acne can also worsen initially before improving, as existing subclinical comedones surface. This is expected and is frequently interpreted as the product not working.
People experience this, conclude their skin doesn't tolerate it, and stop — typically at around three to four weeks, which is before any benefit would be visible.
Visible improvement in photoageing takes months. Trials generally run for six months or longer, and expecting results in weeks guarantees disappointment.
How to start without the misery
Most of the tolerance problem is avoidable with a few adjustments.
Start low and infrequent. Twice a week initially, increasing gradually over weeks as tolerance develops. Building up over two months is entirely reasonable.
Use a small amount. A pea-sized quantity for the entire face. More is not better and substantially increases irritation.
Apply to dry skin. Applying to damp skin increases penetration and irritation. Waiting twenty minutes after washing helps considerably.
The sandwich method. Moisturiser, then retinoid, then moisturiser. Reduces irritation with some reduction in potency, which is a good trade when starting.
Avoid stacking actives. Combining with exfoliating acids, vitamin C and other actives in the same routine compounds irritation. Simplify while adapting.
Skip the eye area initially, and use only a very small amount there later — the skin is thinner and more reactive.
Sun sensitivity
Retinoids increase photosensitivity, and sun exposure also degrades some forms.
Practical consequences: apply at night, and use sunscreen daily. The second point is not optional — using a retinoid without sun protection is working against yourself, since UV exposure causes the damage the retinoid is addressing.
This is also the argument for using them together, which is essentially the entire evidence-based skincare routine in two products.
Who shouldn't use them
Important safety points.
Pregnancy. Oral retinoids are strongly teratogenic. Topical retinoids are generally advised against during pregnancy and breastfeeding as a precaution, and anyone pregnant, planning pregnancy or breastfeeding should discuss this with their doctor.
Certain skin conditions. Active eczema, rosacea and compromised skin barrier may be worsened. Worth discussing with a clinician.
Alongside certain procedures. Generally paused before waxing, laser treatment and some other procedures.
Realistic expectations
For acne, improvement typically over two to three months with consistent use.
For photoageing, meaningful change over six months to a year, and the effect is improvement in texture, fine lines and tone rather than transformation.
Deeper wrinkles and significant laxity are not addressed by topical treatment, whatever the marketing claims.
And the benefit requires continued use. Stopping means gradual return towards baseline, which makes this a long-term commitment rather than a course of treatment.
General information only. Consult a healthcare professional or dermatologist for advice specific to your skin, and particularly if you are pregnant or have a skin condition.
Cost and formulation
A note on spending, since price varies enormously across products containing the same active.
Prescription tretinoin is frequently among the cheapest options where it is available, since it is an old generic medicine. Over-the-counter products containing lower-potency forms are often considerably more expensive per unit of active ingredient.
What you are paying for in expensive formulations is generally the delivery system, the texture and the accompanying ingredients rather than the retinoid itself. Some of that has value — encapsulated forms can reduce irritation — and a great deal of it is packaging and positioning.
If access to a prescription is possible, that is worth exploring before spending substantially more on a weaker product. And for anyone starting out, an inexpensive adapalene product where available is a well-evidenced and well-tolerated entry point.