Tretinoin is a prescription vitamin A cream, the most studied topical treatment for the fine lines, rough texture, and uneven color that sun leaves in skin, and a first-line treatment for acne. In a controlled trial, 14 of 15 faces treated with 0.1% tretinoin improved in photoaging over 16 weeks while none of the placebo-treated faces did, and the improvement holds and builds over a year of nightly use. It works by prompting the skin to rebuild the collagen that sun breaks down: 10 to 12 months of tretinoin raised collagen formation about 80% against a slight fall on the placebo cream. For acne, dermatology guidelines rate topical retinoids a strong first choice, and pairing one with benzoyl peroxide clears about 26% more spots than a placebo cream.
The trade is irritation: redness, peeling, and a few weeks where acne can look worse before it settles, most of it eased by using a pea-sized amount every second or third night at first, buffering with moisturizer, and wearing sunscreen by day. Tretinoin is avoided in pregnancy. It is prescription-only in the United States.
Findings & Outcomes
What It Is
Tretinoin is all-trans-retinoic acid, the active form of vitamin A, applied to the skin as a cream, gel, or lotion. It is a prescription medicine in the United States, sold under names like Retin-A and as generic tretinoin, and it is the reference point every other retinoid is measured against. Weaker relatives sit around it: adapalene and the over-the-counter retinol and retinaldehyde in cosmetics convert to the same acid in the skin but more slowly and gently.
Two uses carry the strongest evidence. The first is photoaging, the fine lines, rough texture, and blotchy color that come from years of sun rather than from age alone. The second is acne, where tretinoin unclogs pores and dermatology guidelines rank it as a first-line treatment. The same cream does both because it changes how skin cells mature and how the dermis underneath rebuilds itself.
What It Does
Start with photoaging, because it is where the evidence is oldest and cleanest. In a 16-week randomized, double-blind trial where each person wore tretinoin on one side and a matching placebo cream on the other, 14 of 15 tretinoin-treated faces improved in fine wrinkling, roughness, and dyspigmentation, while none of the placebo faces did. Later 48-week multicenter trials of tretinoin emollient cream at 0.05% and 0.01% showed the improvement holds and keeps building across a year, and that side effects settle as skin adapts. What tretinoin softens is the shallow sun damage: fine lines, texture, and pigment. It does little for deep folds or sagging, and the gains fade if you stop.
For acne, the 2024 American Academy of Dermatology guideline makes a strong recommendation for topical retinoids, tretinoin among them. In a network meta-analysis of 179 randomized trials, a topical retinoid combined with benzoyl peroxide cleared about 26% more lesions than a placebo cream in mild-to-moderate acne. Retinoids work on the plugged pore itself, which is why they treat both the inflamed spots and the small bumps that precede them, and why they are used to keep acne away once it clears rather than only to knock it down.
The trade is irritation, and the trials are clear that more is not better. In a 48-week study, 0.1% and 0.025% tretinoin improved photoaging by the same amount, but the higher strength caused significantly more redness and scaling. The benefit does not come from the irritation; it comes from the drug, so a lower strength used consistently is the sensible starting point.
People wanting a gentler option often land on copper peptides, sold for the same sun-aged skin. The human evidence behind them is far thinner than tretinoin's, which is why tretinoin is the one to reach for first.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Skin And Hair
Nearly every tretinoin-treated face improved in photoaging while none of the placebo faces did
Tretinoin is the best-studied cream for softening fine sun lines, smoothing rough texture, and evening out sun-driven discoloration. In trials nearly every treated face improved and almost none of the placebo faces did, and the gains hold up and keep building over a year.
In a 16-week randomized, double-blind, vehicle-controlled trial, 14 of 15 faces treated with 0.1% tretinoin improved in photoaging (fine wrinkling, tactile roughness, and dyspigmentation), while 0 of 15 vehicle-treated faces improved. Separate 48-week multicenter double-blind trials of tretinoin emollient cream at 0.05% and 0.01% maintained and further improved photodamage across a year of once-daily use, with side effects easing over time. Measured in: Adults with facial and forearm photodamage across a 16-week crossover trial and 48-week multicenter maintenance trials. The clear trial gains are in fine wrinkling, roughness, and pigment; tretinoin does little for deep folds or sagging, and the improvement fades if you stop using it.
The studies · 2
Weiss et al., Topical tretinoin improves photoaged skin · JAMA 1988;259(4):527-532
Olsen et al., Tretinoin emollient cream for photodamaged skin, 48-week multicenter double-blind studies · J Am Acad Dermatol 1997;37(2 Pt 1):217-226
Topical retinoids are a strongly recommended first-line acne treatment; a retinoid plus benzoyl peroxide cleared about 26% more lesions than placebo
For acne, tretinoin is a first-line treatment that unclogs pores, and dermatology guidelines strongly recommend topical retinoids. Pairing one with benzoyl peroxide clears noticeably more spots than a placebo cream.
The 2024 American Academy of Dermatology guideline makes a strong recommendation for topical retinoids, tretinoin among them, in acne. In a network meta-analysis of 179 randomized trials, a topical retinoid combined with benzoyl peroxide reduced total lesions by about 26% more than placebo in mild-to-moderate acne (mean difference 26.16%, 95% credible interval 16.75 to 35.36). Measured in: Adolescents and adults with acne across a GRADE-based guideline and a 179-trial network meta-analysis. Retinoids irritate and can dry or redden skin in the first weeks and often cause an early flare; starting every other night with a moisturizer is how most people get past that.
The studies · 2
Reynolds et al., Guidelines of care for the management of acne vulgaris · J Am Acad Dermatol 2024;90(5):1006.e1-1006.e30
Mavranezouli et al., systematic review and network meta-analysis of treatments for acne vulgaris · Br J Dermatol 2022;187(5):639-649
A higher tretinoin strength was more irritating without being more effective for photoaging
Higher-strength tretinoin is not more effective for photoaging but is more irritating. A lower strength works about as well with less redness and peeling, which is why starting low and building up makes sense.
In a 48-week double-blind, vehicle-controlled trial (n=99), 0.1% and 0.025% tretinoin creams improved facial photoaging by a similar, statistically significant amount versus vehicle, but erythema and scaling were significantly more common at 0.1% than at 0.025%. The authors concluded irritation was dose-related and not the cause of the benefit. Measured in: 99 photoaged adults completing a 48-week face trial of 0.1% tretinoin, 0.025% tretinoin, or vehicle. Irritation, dryness, and peeling are common in the first weeks for most people, and acne can flare before it improves; these ease with less frequent use and moisturizer and are not a sign the cream is failing.
Who this may not transfer to:Retinoid dermatitis is a direct skin-barrier effect not specific to sex, and it is reported across trials that enrolled both men and women, so the dose-related irritation is expected to transfer.
The study · 1
Griffiths et al., Two concentrations of topical tretinoin cause similar improvement of photoaging but different degrees of irritation · Arch Dermatol 1995;131(9):1037-1044
A tretinoin gel showed low phototoxic and photoallergic potential under controlled light challenge
Formal light-exposure testing of a tretinoin gel found little sign that it makes skin burn or react in sunlight. Daily sunscreen still holds, because tretinoin can leave fresh skin more sensitive early on and sun is what causes the damage it treats.
In two randomized, evaluator-blinded, vehicle-controlled phase 1 studies in healthy volunteers, a fixed combination of clindamycin 1.2% and tretinoin 0.025% gel showed low phototoxic and photoallergic potential under UVA, UVB, and visible-light challenge, with most subjects showing no inflammatory reaction after irradiation and one photoallergic discontinuation. Measured in: 95 healthy volunteers across a phototoxicity study (n=37) and a photoallergy study (n=58). This tested one combination gel at a low concentration, not tretinoin at higher strengths or over long use; product labeling still advises minimizing sun exposure and using sunscreen.
Who this may not transfer to:Phototoxic and photoallergic potential is a property of the drug and formulation rather than of the wearer's sex, so the low potential seen in mixed healthy volunteers is expected to transfer.
The study · 1
Murray et al., The phototoxic and photoallergy potential of clindamycin phosphate 1.2%/tretinoin 0.025% gel · J Drugs Dermatol 2014;13(1):16-22
How it works
Tretinoin partly restored the collagen formation that sun damage had lowered
Sun damage lowers the skin's collagen. Tretinoin prompts the skin to make substantially more of it again over about a year, which is the change behind the smoother texture people see.
Collagen I formation was 56% lower in sun-damaged forearm skin than in sun-protected skin from the same people (P < 0.001) and tracked the clinical severity of photodamage. In a double-blind vehicle-controlled trial, 10 to 12 months of nightly 0.1% tretinoin cream raised collagen I formation about 80%, against a 14% decline under vehicle cream (P = 0.006). Measured in: 26 subjects biopsied for baseline collagen plus 29 patients treated for 10 to 12 months with tretinoin or vehicle. This measured collagen in forearm skin in a small study, so it shows the mechanism rather than a cosmetic endpoint, and the rebuilding takes the better part of a year.
Who this may not transfer to:The mechanism is dermal collagen synthesis, not a sex-specific pathway, and the clinical photoaging trials that rest on it enrolled both sexes, so the finding is expected to transfer.
The study · 1
Griffiths et al., Restoration of collagen formation in photodamaged human skin by tretinoin · N Engl J Med 1993;329(8):530-535
How It Works
Tretinoin binds receptors inside skin cells and changes which genes those cells read. In the epidermis it speeds up the turnover of surface cells and loosens the glue between the dead cells that plug pores, which is the acne effect. Deeper down, it acts on the collagen that gives skin its firmness.
Sun damage runs collagen down. In sun-exposed forearm skin, collagen formation measured 56% lower than in sun-protected skin from the same people, and the drop tracked how sun-damaged the skin looked. After 10 to 12 months of nightly 0.1% tretinoin, collagen formation rose about 80%, while the placebo cream showed a 14% fall.
Tretinoin does not resurface skin from the outside. It signals the living cells underneath to rebuild collagen the sun has degraded, and that rebuilding takes the better part of a year, which is why the visible change is slow and why stopping lets it reverse.
How to Use It
Ways to Do It
Tretinoin is prescription-only in the United States, so the first step is a clinician who can match the strength to your skin. Almost everything that goes wrong with it comes from using too much too soon. The dose that works is small and consistent, so the goal is a routine your skin tolerates every week rather than the strongest cream you can get. Start at the first rung and move up only once your skin is calm.
A clinician can start you on a lower strength such as 0.025% tretinoin, which trials show works as well for photoaging as higher strengths with less irritation. Use a pea-sized amount for the whole face, at night, every second or third night at first, on dry skin. Build up to nightly only once that is comfortable, which for most people takes a few weeks to a couple of months.
Apply a plain moisturizer before or after the pea-sized dose to soften the early redness and peeling, and expect a stretch where skin looks worse and acne can flare before it improves. This purging settles. Keeping the frequency low and the moisturizer generous is how most people stay on it long enough to see the benefit rather than quitting in week two.
Use a broad-spectrum sunscreen of SPF 30 or higher every morning. Sun is what causes the damage tretinoin treats, fresh skin can be more sun-sensitive early on, and daylight breaks tretinoin down, which is why it is a night cream. Judge it at three to six months, not three weeks; the collagen change behind the smoother texture takes the better part of a year.
The Chinese Medicine View
Chinese medicine has nothing that maps to tretinoin, and it is more accurate to say so than to build a bridge that is not there. The tradition treats skin from the inside, reading acne and dull, dry skin through patterns such as Lung and Stomach heat, damp-heat, or Blood dryness, and it works through herbs, diet, and lifestyle rather than a topical drug that reprograms skin cells. A synthetic vitamin A acid sits outside that framework entirely.
Where the two frames touch is in caution rather than mechanism. A practitioner reading a person as having heat and dryness in the skin would expect a drying, reddening treatment to aggravate that picture at first, which lines up with the irritation tretinoin causes early on, and would pair it with measures to cool and moisten. That is a reason to go slow, not evidence that the tradition anticipated the drug.
Right before the cautions, one line matters more than the rest:
Topical tretinoin is avoided in pregnancy. Studies of accidental early exposure have not shown a clear rise in birth defects, but the data are too thin to call it safe, and because vitamin A acid taken by mouth is a potent cause of birth defects, the standing advice is to stop tretinoin while trying to conceive and throughout pregnancy.
Cautions For This Practice
Extra restraintEverything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
First-trimester topical retinoid exposure was not linked to a significant rise in birth defects, but the data cannot justify use in pregnancy
A systematic review and meta-analysis of 654 first-trimester topical-retinoid-exposed pregnancies versus 1,375 unexposed controls did not detect significant increases in major congenital malformations (OR 1.22, 95% CI 0.65 to 2.29), spontaneous abortion (OR 1.02, 95% CI 0.64 to 1.63), low birth weight (OR 1.01, 95% CI 0.31 to 3.27), or prematurity (OR 0.69, 95% CI 0.39 to 1.23). The authors judged the result reassuring after inadvertent exposure but underpowered to justify deliberate use. The number of exposed pregnancies is small, so a real risk cannot be ruled out; oral retinoids are potent causes of birth defects, and the standing guidance is to stop topical tretinoin while trying to conceive and during pregnancy.Kaplan et al., Pregnancy outcomes following first-trimester exposure to topical retinoids
Do not use in pregnancy or when trying to conceive
Topical tretinoin is avoided in pregnancy. A meta-analysis of women exposed in the first trimester did not find a significant increase in birth defects, which is reassuring after an accidental exposure, but the numbers are small and cannot rule out an increased risk. Oral retinoids are among the strongest known causes of birth defects. Stop tretinoin while trying to conceive, during pregnancy, and discuss breastfeeding with your clinician.
Expect irritation, and an early acne flare
Redness, dryness, stinging, and peeling are common in the first weeks, and acne can look worse before it improves. This eases with less frequent use, a lower strength, and moisturizer, and is not a sign the cream is failing. If irritation is severe, cracking, or not settling, cut back the frequency or speak to your clinician rather than pushing through.
Protect against sun and cold, dry weather
Wear a broad-spectrum SPF 30 or higher every day. Sun causes the damage tretinoin treats, and skin can be more sun-sensitive in the early weeks. Wind, cold, and low humidity all worsen the dryness, so winter often calls for less frequent use and more moisturizer.
Watch what you combine it with
Layering tretinoin with strong exfoliating acids, benzoyl peroxide in the same application, or physical scrubs multiplies the irritation. Benzoyl peroxide pairs well for acne but is usually best used at a different time of day. Waxing over treated skin can tear it. Tell your clinician about every skincare product and any other retinoid you use.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
How long before I see anything, and does it get worse first?
For acne, expect the first clear improvement around 8 to 12 weeks, often after an early stretch where spots look worse, which is the pores clearing out and settles. For photoaging, texture and tone start shifting over a few months and the collagen change behind smoother skin takes the better part of a year. Judge tretinoin at three to six months, not three weeks. The redness and peeling of the first weeks are the adjustment, not the result.
Is a stronger tretinoin better, and how much should I use?
No. In a head-to-head trial, 0.1% and 0.025% tretinoin improved photoaging by the same amount, but the higher strength was significantly more irritating. A pea-sized amount covers the whole face; more does not work faster and mostly buys you redness and peeling. Most people do best starting at a lower strength, every second or third night, and building up to nightly only once their skin is calm.
Can I use tretinoin if I am pregnant or breastfeeding?
Tretinoin is avoided in pregnancy. A meta-analysis of first-trimester exposures did not find a clear rise in birth defects, which is reassuring after an accidental application, but the evidence is not strong enough to call it safe, and oral vitamin A acid is a well-established cause of birth defects. Stop while trying to conceive and during pregnancy, and ask your clinician about breastfeeding before restarting.
Do I really need sunscreen with it?
Yes, for two reasons. Sun is the cause of the photoaging tretinoin treats, so daily broad-spectrum SPF 30 or higher protects the gains you are working for. Fresh skin turned over by tretinoin can also be more sun-sensitive in the early weeks. Formal light-testing of a tretinoin gel found low potential to make skin burn or react, so the sunscreen is mainly about prevention and comfort, not a warning that the cream itself is dangerous in daylight.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 8 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 10, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.