Retinol vs Tretinoin: How Retinoids Work and What the Evidence Shows

Retinoids are the rare skincare ingredient that dermatologists and the beauty industry agree on. They are also the source of more confusion than almost anything else on the shelf: retinol, retinal, retinyl palmitate, tretinoin, adapalene, “retinol alternatives”, and percentages that do not mean the same thing from one ingredient to the next.

The short version: they all aim to do the same job, they differ mainly in strength and in how much evidence stands behind them, and the strongest ones need the most careful introduction. This guide explains how retinoids work, how good the evidence is for each, how to start without wrecking your skin barrier, and the pregnancy warning that applies to all of them.

How retinoids work

Retinoids are compounds related to vitamin A. The active form in skin is retinoic acid (the drug name is tretinoin). It enters skin cells and binds to retinoic acid receptors in the nucleus, which change which genes are switched on. The visible results:

• Faster turnover of the outer skin cells, so the surface becomes smoother and pores are less likely to clog — the main reason retinoids treat acne.
• More collagen in the dermis and less activity of the enzymes that break collagen down after sun exposure — the main reason they soften fine lines.
• More even pigmentation over months.

Cosmetic retinoids are precursors that skin enzymes convert, step by step, into retinoic acid:

retinyl esters (e.g. retinyl palmitate) → retinol → retinaldehyde (retinal) → retinoic acid

Each step converts only part of what is applied, so each form further back is weaker, slower and gentler than the one after it. Adapalene and tazarotene are different again: synthetic molecules designed to act on the receptors directly, with no conversion needed.

The evidence, tier by tier

Tretinoin: the benchmark

Tretinoin has been used for acne since the early 1970s. Its role in ageing skin was established in a 1988 double-blind trial: 30 people applied tretinoin to one forearm and an inactive cream to the other, and half also used tretinoin on the face. Every tretinoin-treated forearm improved, and 14 of 15 tretinoin-treated faces improved, while none of the placebo-treated faces did. The only side effect was irritation. Strong evidence1 study

The most useful follow-up for anyone choosing a strength came in 1995. Ninety-nine people with sun-damaged skin used 0.1% tretinoin, 0.025% tretinoin or a placebo cream daily for 48 weeks. Both strengths improved photoageing equally and thickened the epidermis similarly, but the 0.1% cream caused significantly more redness and peeling. Strong evidence1 study In other words, irritation is not the mechanism, and more is not better. Starting low is not a compromise.

Retinol: real, but slower and smaller

The best-known retinol trial was run by the same University of Michigan group that did much of the tretinoin work. Thirty-six elderly residents of care homes (average age 87) had 0.4% retinol lotion applied to one arm and an inactive lotion to the other, up to three times a week for 24 weeks. Fine wrinkling improved on the retinol arm, and skin biopsies showed more collagen production and more water-holding molecules in the dermis. Moderate evidence1 study

That was forearm skin in very old people, not faces in 40-year-olds. A direct comparison funded and largely run by a cosmetics company found that retinol produced the same kinds of changes as retinoic acid over four weeks — thicker epidermis, more collagen gene activity — but smaller in size, plus fewer facial wrinkles after 12 weeks of retinol use. Emerging evidence1 study Together, the evidence supports retinol as a genuine, milder alternative to tretinoin — with results measured in months, not weeks.

Retinal and retinyl esters

Retinaldehyde is one conversion step from retinoic acid and is often marketed as “faster than retinol”. That is plausible, but the published trials are small. Retinyl palmitate and other esters are three steps away, and there is little good evidence that they do much for wrinkles at the concentrations used in moisturisers and daytime creams. Treat them as a label feature, not an active treatment.

Adapalene: the over-the-counter acne option

For acne, the American Academy of Dermatology’s 2024 guideline makes a strong recommendation for topical retinoids, alongside benzoyl peroxide. Strong evidence1 study Adapalene is the retinoid most people can reach first: 0.1% gel has been sold without a prescription in the US since 2016. In a 653-person trial comparing 0.3%, 0.1% and an inactive gel over 12 weeks, both strengths beat the inactive gel and the higher strength did best, with side effects that were mostly mild and short-lived. Strong evidence1 study Adapalene is chemically stable alongside benzoyl peroxide, which is why the two are often combined. Its evidence for wrinkles is thinner than tretinoin’s.

Bakuchiol: promising, small

Bakuchiol is a plant compound, not a retinoid, that switches on some of the same genes in laboratory work. In the one head-to-head trial, 44 people used 0.5% bakuchiol twice daily or 0.5% retinol once daily for 12 weeks. Both reduced wrinkle area and pigmentation by a similar amount, and the retinol group reported more scaling and stinging. Emerging evidence1 study That is encouraging, but it is one small trial, and a trial that finds “no difference” with 44 people cannot show two treatments are equivalent. Bakuchiol is a reasonable choice if you cannot tolerate any retinoid. It has not been studied in pregnancy, so “pregnancy-safe retinol alternative” is a marketing claim, not a finding.

Strengths: which to start with

• First retinoid, anti-ageing, normal or dry skin: retinol around 0.25–0.5%, or, if you are seeing a clinician, tretinoin 0.025%.
• Sensitive skin: the lowest retinol you can find, two nights a week, applied over moisturiser.
• Acne: adapalene 0.1% gel every night or every other night, usually with a benzoyl peroxide wash or gel in the morning. If acne is scarring, painful or not improving after about three months, see a clinician.
• Already tolerating retinol well for months: a higher retinol, retinaldehyde, or a prescription retinoid is the next step.

Retinol percentages are not comparable to tretinoin percentages. 1% retinol is not ten times stronger than 0.1% tretinoin; it is weaker.

Irritation, and how to start

Most people get some “retinoid dermatitis” in the first two to six weeks: dryness, flaking, redness, stinging, especially around the mouth and nose. It usually settles as skin adapts. The way to keep it manageable:

1. Use a pea-sized amount for the whole face. More does not work better; it just irritates more.
2. Start two or three nights a week, and add a night every week or two as your skin allows.
3. Apply to dry skin at night, avoiding the corners of the eyes, nostrils and lips.
4. Moisturise. Applying moisturiser before or after (“buffering”) reduces irritation; it may slightly slow results, which is usually a good trade.
5. Pause other exfoliants (glycolic, salicylic, scrubs) for the first month, and do not combine several retinoid products.
6. Keep tretinoin and benzoyl peroxide apart: benzoyl peroxide can break down tretinoin, so use them at different times of day (adapalene does not have this problem).
7. Stop a few days before waxing, peels or laser, which can tear or burn retinoid-treated skin.

Acne may flare briefly in the first weeks (“purging”) as blocked pores come to the surface. Expect acne results at 8–12 weeks and wrinkle or pigment changes over three to six months. Retinoids need to be continued to keep their effect.

Sun sensitivity

Tretinoin is broken down by sunlight, which is one reason retinoids are applied at night. Retinoid-treated skin also tends to burn more easily, and prescription labels advise minimising sun exposure. That makes daily broad-spectrum sunscreen part of any retinoid routine, not an optional extra — and sunscreen is itself one of the best-evidenced ways to prevent visible ageing (see our sunscreen guide). Take extra care if you also take other photosensitising medicines such as doxycycline.

Safety

What’s marketing

• Percentage races. A higher retinol percentage mostly means more irritation. The tretinoin data show the lowest effective strength works as well as a high one.
• “Encapsulated” or “time-release” retinol. May reduce irritation, but independent comparisons are scarce.
• Retinyl palmitate in day creams. Too weak and too far down the conversion chain to count as a retinoid treatment.
• “Natural retinol”. Plant extracts marketed this way (including bakuchiol) are not retinoids. Some may help; the evidence is small.

Frequently Asked Questions

Is retinol as good as tretinoin?

No, but it works. Retinol produces the same kinds of changes more slowly and to a smaller degree, and it is gentler. Many people do well on retinol; tretinoin is the step up if you want the strongest evidence and can see a prescriber.

Can I use retinol with vitamin C?

Yes. The simplest routine is vitamin C in the morning under sunscreen and the retinoid at night, which avoids piling several potentially irritating products on at once.

Can I use a retinoid around my eyes?

Carefully. The skin is thin and irritates easily. Use a tiny amount on the bony area under the eye, stay away from the lash line, or choose a lower-strength product made for that area.

How long until I see results?

For acne, 8–12 weeks. For fine lines and uneven tone, three to six months, with continued improvement over a year in the tretinoin trials. If you stop, the benefits gradually fade.

Is bakuchiol a safe alternative in pregnancy?

We don’t know. Bakuchiol has not been studied in pregnancy, so calling it “pregnancy-safe” goes beyond the evidence. Ask your clinician; ingredients such as azelaic acid have a longer safety record in pregnancy.

The Bottom Line

Retinoids earn their reputation. Tretinoin has the strongest evidence for sun-aged skin, retinol is a real but gentler option, and adapalene 0.1% is the evidence-based over-the-counter choice for acne in the US. Choose the lowest strength that works, introduce it slowly, pair it with daily sunscreen, and stop during pregnancy. For how collagen fits into skin ageing more broadly, see our collagen guide, and the personal care learning track.

Compare retinol serums and treatments on the Formulate personal care shelf →