Retin-A, the brand name for prescription tretinoin, can meaningfully improve several types of scars, though the degree of benefit depends heavily on the scar type and how long it has existed. The strongest evidence supports its use on shallow, atrophic acne scars and on the dark marks (post-inflammatory hyperpigmentation) that acne and other skin injuries leave behind. For raised scars and stretch marks, the picture is murkier. Understanding which scars respond and which do not can save you months of applying a product that was never going to help your particular situation.
How Tretinoin Works on Scarred Skin
Tretinoin is a form of vitamin A that binds to receptors inside skin cells and changes which genes those cells turn on or off. In the context of scarring, the most relevant effects involve collagen production, the speed at which skin cells turn over, and the signaling pathways that drive fibrosis (the process by which scars become dense and stiff). Tretinoin has been shown to suppress a key signaling cascade involving TGF-β1 and Smad proteins, which are among the main drivers of excessive scar tissue formation. It also inhibits the transformation of normal fibroblasts into myofibroblasts, the cells responsible for the contractile, tough quality of mature scars.1PubMed Central. Retinoids in scarless skin regeneration: from molecular mechanisms to therapeutic strategies
On the rebuilding side, tretinoin stimulates production of collagen types I, III, and VI, along with elastin and fibronectin, all of which are structural proteins that give skin its strength and elasticity. In lab studies on human skin cells, the messenger RNA levels for collagen I and fibronectin increased by roughly 90% compared to untreated controls, while elastin increased by about 30%.2PubMed. Effects of tretinoin tocoferil on gene expression of the extracellular matrix components in human dermal fibroblasts in vitro This dual action, dampening the overproduction of scar tissue while encouraging the formation of more normal skin architecture, is what makes tretinoin potentially useful across different scar types rather than just one.
Atrophic Acne Scars
Atrophic scars are the indented, pitted scars that remain after inflammatory acne. They form because the skin loses collagen during the healing process, leaving a depression instead of a flat surface. This is the scar type with the most clinical data supporting tretinoin use, although the delivery method matters.
Several clinical studies have used tretinoin delivered via iontophoresis, a technique that uses a mild electrical current to push the medication deeper into the skin than simple topical application can achieve. In one study, about 79% of patients showed visible flattening of their acne scars after treatment. The best results occurred with newer scars and with superficial or ice-pick type scars.3PubMed. Flattening of atrophic acne scars by using tretinoin by iontophoresis A separate study reported improvement in 93% of patients treated with tretinoin iontophoresis, with effects that persisted after treatment ended. Side effects in that study were limited to increased dryness and mild retinoid dermatitis in a handful of patients.4PubMed. New treatment of atrophic acne scars by iontophoresis with estriol and tretinoin A third trial found that 94% of patients experienced a significant decrease in scar depth after tretinoin iontophoresis, without troubling side effects.5PubMed. Tretinoin-iontophoresis in atrophic acne scars
These numbers sound impressive, but there is an important caveat: iontophoresis is a clinical procedure, not what happens when you rub tretinoin cream on your face at home. Standard topical application delivers tretinoin to the upper layers of skin, while iontophoresis pushes it deeper where scar tissue actually sits. If you are applying over-the-counter or even prescription-strength tretinoin cream at home for acne scars, you should expect more modest results than those reported in iontophoresis studies. Still, the collagen-stimulating effects of even topical tretinoin are well established, and many dermatologists prescribe it as part of a longer-term scar-management plan, often alongside other treatments.
The Dark Marks That Acne Leaves Behind
Many people who search for “acne scar” treatments are actually dealing with post-inflammatory hyperpigmentation, or PIH, which is the flat, discolored patch that lingers after a pimple heals. PIH is not technically a scar in the structural sense since no collagen has been lost or gained. It is a pigment problem, caused by excess melanin deposited during the inflammatory healing process. But the distinction barely matters to someone staring at dark spots on their face, and tretinoin addresses these effectively.
Tretinoin tackles PIH through two separate mechanisms. It speeds up epidermal turnover, so the pigment-loaded skin cells are shed faster. It also blocks the transfer of melanin-containing packets from the cells that produce them to the surrounding skin cells, which slows the resupply of dark pigment. In a 40-week controlled study of 68 Black men and women with hyperpigmented lesions from acne, shaving irritation, eczema, and other causes, tretinoin 0.1% cream produced visible improvement starting as early as week four. A related retinoid, tazarotene, achieved statistically significant reductions in hyperpigmentation severity, intensity, and area compared to a vehicle cream.6PubMed Central. Effects of Topical Retinoids on Acne and Post-inflammatory Hyperpigmentation in Patients with Skin of Color: A Clinical Review and Implications for Practice
This is particularly relevant for people with darker skin tones, who are more prone to PIH and for whom many laser and chemical-peel treatments carry a higher risk of making pigmentation worse. Tretinoin offers a lower-risk option that can be used at home under a dermatologist’s guidance. Just know that sun protection is non-negotiable while using it, since tretinoin makes skin more photosensitive, and UV exposure will undo the pigment-fading progress.
Hypertrophic Scars and Keloids
Hypertrophic scars and keloids are the opposite of atrophic scars. They involve too much collagen, producing raised, sometimes painful tissue at the site of an injury. Keloids extend beyond the original wound margins, while hypertrophic scars stay within them. Both are notoriously stubborn to treat.
The evidence for tretinoin here is thinner and tends to focus on prevention rather than treatment of established scars. One study compared topical tretinoin cream to silicone gel (a standard scar-prevention product) in patients at risk of developing hypertrophic scars or keloids. Both treatments effectively prevented these raised scars and improved existing scar appearance compared to an untreated control group, with no significant difference between the two treatment arms.7PubMed. Comparative effect of topical silicone gel and topical tretinoin cream for the prevention of hypertrophic scar and keloid formation and the improvement of scars That is a meaningful finding because silicone gel is widely considered one of the most reliable topical options for scar prevention, so tretinoin performing comparably suggests real utility.
However, tretinoin alone is rarely used as the primary treatment for a fully developed keloid. Keloid management typically involves corticosteroid injections, pressure therapy, silicone sheets, or surgical revision, sometimes combined with radiation. Tretinoin’s role in this space is more as a supporting player or a preventive measure after wound closure. If you have a mature, raised keloid, tretinoin cream is unlikely to flatten it on its own.
Stretch Marks
Stretch marks, known in dermatology as striae distensae, are a form of scarring caused by rapid stretching of the skin during growth spurts, pregnancy, or weight changes. They start out reddish or purple (striae rubrae) and gradually fade to silvery-white (striae albae). Tretinoin has been studied for both stages, but the results are genuinely mixed.
A review of the topical treatments available for stretch marks found that tretinoin produced variable results. Some patients saw improvement, while others saw little change. The same review noted that popular alternatives like cocoa butter and olive oil showed no measurable effect at all, which at least puts tretinoin ahead of those options. A persistent weakness in this literature is that most studies did not differentiate between treatment of newer red stretch marks versus older white ones, making it hard to know exactly when tretinoin is most useful.8PubMed Central. Topical management of striae distensae (stretch marks): prevention and therapy of striae rubrae and albae
The general clinical consensus, backed by the biology of how stretch marks mature, is that tretinoin has a better shot at improving newer, redder stretch marks than older, white ones. Striae rubrae still have active blood flow and ongoing remodeling. Once a stretch mark has faded to white, the tissue is largely inert, and topical tretinoin is unlikely to rebuild the lost elastin and collagen at that depth. If you are going to try tretinoin for stretch marks, starting early during the red phase gives you the best odds. Even then, complete elimination is unlikely.
Burn Scars and Combination Approaches
Burn scars present a unique challenge because the injury typically damages multiple layers of skin simultaneously, resulting in scars that can be hypertrophic, discolored, and contractile all at once. Tretinoin is rarely used alone for burn scars, but it has been incorporated into combination regimens with promising results. In one documented case, a patient with hypertrophic scarring from a skin graft for second-degree burns was treated with long-pulsed Nd:YAG laser sessions combined with topical tretinoin and hydroquinone. After ten months, the scar showed improvements in color, contour, and texture.9International Journal of Medical Science and Clinical Research Studies. Managing Burn Scar with a Combination Therapy of Long Pulsed 1064 Nm Nd: YAG (LPND) Laser, Topical Tretinoin and Hydroquinone
This kind of multi-modal strategy reflects how tretinoin tends to be used in practice for more severe scars. It works best as part of a team rather than a solo performer. Common combinations include tretinoin paired with chemical peels, microneedling, or laser treatments. One pilot protocol, for instance, combined 35% glycolic acid peels and microneedling on the first day, followed by daily application of 0.05% tretinoin with 12% glycolic acid for two months, then another round of peeling.10Our Dermatology Online. Zonun’s regime (35% glycolic acid peel with microneedling followed by tretinoin 0.05% plus glycolic acid 12% application followed by salicylic acid 30% peeling) for treatment of acne scars: a pilot study The idea behind these combination protocols is that procedures like microneedling and peels create controlled micro-injuries that trigger the skin’s healing response, while tretinoin applied afterward steers that healing process toward better collagen organization rather than more scar tissue.
Using Tretinoin Before Procedures
You may have heard that dermatologists ask patients to use tretinoin for several weeks before laser resurfacing, deep chemical peels, or other facial procedures. The rationale is that pre-treating the skin with tretinoin speeds up cell turnover and primes the tissue for faster, better-quality healing after the procedure. Some practitioners believe it also allows the skin to respond more uniformly to the procedure itself.
The actual evidence behind this practice is surprisingly thin. A literature review found that there are no definitive recommendations for how to use tretinoin before facial procedures. Regimens vary wildly in the concentration used, how long patients apply it before the procedure, and when they stop before the procedure day.11PubMed Central. Retinoids: Literature Review and Suggested Algorithm for Use Prior to Facial Resurfacing Procedures Some dermatologists swear by two to six weeks of pre-treatment; others skip it entirely and see comparable outcomes. If your provider asks you to start tretinoin before a procedure, it is a reasonable and low-risk step, but if they do not mention it, the omission is not a red flag either.
Why Scar Age Matters More Than You Might Think
One of the most consistent findings across the scar literature is that newer scars respond better to tretinoin than older ones. This holds true across scar types: atrophic acne scars that are months old respond better than those that have been settled for years.3PubMed. Flattening of atrophic acne scars by using tretinoin by iontophoresis Red stretch marks respond better than white ones. Recently closed surgical wounds are more amenable to preventive treatment than fully matured scars.
The biology behind this pattern is straightforward. In the first months after an injury, the scar tissue is still actively remodeling. Fibroblasts are producing and reorganizing collagen, blood vessels are forming and receding, and the extracellular matrix is in flux. Tretinoin can influence these processes while they are still happening. Once a scar has fully matured, which can take a year or more, the tissue is largely stable. Collagen fibers have cross-linked into their permanent arrangement, and the cells within the scar have become much less metabolically active. At that point, a topical treatment that works by altering cell behavior has far less to work with. This does not mean old scars are completely hopeless, but it does mean that starting tretinoin sooner rather than later gives you significantly better odds.
What About Over-the-Counter Retinol
Retinol, retinaldehyde, and various other retinoid derivatives are available without a prescription and marketed aggressively for anti-aging, acne, and scar treatment. These are all related to tretinoin, but they are not the same molecule. Your skin has to convert retinol into retinaldehyde, and then into retinoic acid (tretinoin) before it becomes active. Each conversion step is inefficient, so the amount of active ingredient that actually reaches your skin cells from a retinol product is a fraction of what prescription tretinoin delivers directly.
For general skin health, fine lines, and mild discoloration, over-the-counter retinol can be worthwhile. For meaningful scar treatment, the clinical evidence is almost entirely based on prescription-strength tretinoin. The studies on atrophic acne scars, PIH, and hypertrophic scar prevention all used tretinoin, not retinol. If you are serious about treating scars and not just maintaining overall skin quality, prescription tretinoin is the version with data behind it. That said, retinol can be a reasonable starting point if your skin has never been exposed to retinoids before, since it causes less irritation and lets you build tolerance before stepping up to the prescription product.
Side Effects and How to Manage Them
Tretinoin irritates the skin. That is not a risk so much as a near-certainty when you first start using it. The classic experience includes redness, peeling, dryness, and a temporary worsening of appearance that dermatologists sometimes call the “retinoid ugly phase.” On scarred skin, which may already have a compromised barrier, this irritation can be more intense than on unscarred areas.
A few practical strategies reduce the misery:
- Start low: Begin with the lowest available concentration (typically 0.025%) and apply every other night or every third night until your skin adjusts.
- Buffer it: Apply a plain moisturizer first, wait a few minutes, then apply tretinoin on top. This “sandwich” or buffering technique reduces direct contact irritation without eliminating the active ingredient’s effects.
- Protect from sun: Use a broad-spectrum sunscreen daily. Tretinoin thins the outermost layer of skin and increases UV sensitivity, which can worsen pigmentation problems and cause burns.
- Skip sensitive areas: Avoid applying directly to skin that is cracked, peeling severely, or actively inflamed. Wait until the acute irritation settles before resuming.
The irritation phase typically lasts two to six weeks and then largely resolves as your skin acclimates. If it does not improve, dropping to a lower concentration or less frequent application is usually the answer. In the iontophoresis studies on acne scars, side effects were mild, with retinoid dermatitis appearing in only a few patients.4PubMed. New treatment of atrophic acne scars by iontophoresis with estriol and tretinoin Topical use carries essentially no systemic risks at the concentrations used for scar treatment, though tretinoin is strictly contraindicated during pregnancy due to the known teratogenic effects of oral retinoids.
Oral Isotretinoin and Scar Remodeling
Isotretinoin (brand name Accutane, among others) is an oral retinoid most commonly prescribed for severe cystic acne. It works throughout the body rather than just on the skin surface, and there is some evidence that it may influence scar remodeling from the inside out. One study measured changes in acne scars using an imaging technique called shear-wave elastography and found that after 90 days of oral isotretinoin, patients showed statistically significant improvements in scar severity scores. Scar size and dermal thickness decreased, while the elasticity of the tissue beneath the scars increased.12PubMed Central. The Effects of Oral Isotretinoin on Atrophic Acne Scars Measured by Shear-wave Elastography: An Observational, Single-center Study
This is intriguing but still preliminary. Oral isotretinoin is a serious medication with a long list of potential side effects, including dry skin and mucous membranes, elevated liver enzymes, mood changes, and birth defects if taken during pregnancy. No dermatologist is going to prescribe it solely for scar treatment. But if you are already on isotretinoin for active acne, the scar-improving effects may be a welcome bonus. It also complicates the traditional advice that patients should wait six months to a year after finishing isotretinoin before undergoing laser resurfacing or other ablative procedures, since some of the scar remodeling may already be underway.
Scars That Tretinoin Will Not Fix
Tretinoin has real limits. Deep boxcar and rolling acne scars, where significant volumes of tissue are missing below the skin surface, are unlikely to fill in from a topical treatment alone. These typically require subcision, filler injections, fractional laser, or punch excision to see meaningful improvement. Tretinoin can complement those procedures but does not replace them for deeper structural defects.
Similarly, mature white stretch marks, scars from major surgery with wide or irregular margins, and contracture scars from burns that restrict movement are all beyond what topical tretinoin can meaningfully address. In these cases, the tissue damage is too deep or too structurally complex for a cream that primarily affects the upper layers of skin. Recognizing these boundaries is important because months spent on an ineffective topical treatment are months not spent pursuing procedures that might actually help.