Retinoids are the second-best-evidenced thing in this magazine, after sunscreen. They are also the category with the highest abandonment rate, and those two facts are related: a product that takes three months to demonstrate anything is competing for shelf space against products that appear to do something on the first night.
The conversion problem
Not all retinoids are the same molecule and the difference is not a marketing tier. Tretinoin is retinoic acid — the active form, which binds directly to nuclear receptors and needs no conversion. Everything sold over the counter is a precursor that has to be converted in the skin to get there.
Retinaldehyde converts in one step. Retinol takes two. Retinyl palmitate and the other esters take three, and each step loses a great deal of material. The practical consequence is that potency runs roughly tretinoin, then retinaldehyde, then retinol, then the esters — and that a 1 per cent retinyl palmitate is not remotely comparable to a 0.3 per cent retinol, whatever the number on the front suggests.
The newer retinoid esters that bind directly, granactive-type compounds among them, sit somewhere between retinol and retinaldehyde and are considerably better tolerated. They are a reasonable starting point for anyone who has failed at retinol twice.
The schedule is the product
Two nights a week for four weeks. Three nights a week for four weeks. Then, only if there has been no persistent flaking or stinging, every other night.
Most people go nightly on day one, spend two weeks visibly peeling, conclude their skin cannot tolerate retinoids, and stop. The retinisation period is real — the initial adjustment involves genuine barrier disruption — but it is proportional to how fast you push, and the endpoint is the same either way. Going slowly costs six weeks and saves the attempt.
Apply to dry skin, at least twenty minutes after cleansing. Damp skin increases penetration, which sounds like an advantage and is in fact the most common cause of irritation on a first attempt.
What to expect, and when
Weeks one to four: nothing good. Possibly some purging, which is genuine — accelerated turnover brings existing microcomedones to the surface — and which is distinguishable from a reaction because it happens where you normally break out.
Weeks four to twelve: texture. This is the first real change, and it is the one people miss because it is gradual and they are looking for something else.
Weeks twelve to twenty-four: tone, and the beginning of fine-line change. The collagen data underlying the anti-wrinkle claims comes from studies running six months to a year, not eight weeks.
If you have not given it twelve weeks, you do not have an opinion about it yet.
The three rules that matter
Sunscreen, non-negotiably, every morning. Retinoids thin the stratum corneum initially and photosensitivity is real.
Do not layer it with an exfoliating acid on the same night. There is no additive benefit and there is a well-documented additive irritation.
And buy the opaque, airless packaging. Retinol oxidises in light and air, and a clear jar is a product that will be inert before you finish it — which is, incidentally, the cheapest way for a brand to sell a retinoid that never irritates anybody.
