Ever wondered why some acne scars soften over time while others seem to stay put for years? In this guide, our pharmacists explain how tretinoin for scars works deep in your skin, which scars it can realistically improve, how long you’ll wait for results, and how to use it without turning your face into a flaky mess.
This blog on the mechanism of action of tretinoin is a pharmacist’s guide to smoother skin
Five key takeaways
- Tretinoin is a prescription vitamin A medicine that speeds up skin cell turnover and encourages your skin to make fresh collagen, which is why it can help soften some scars.
- It works best on shallow atrophic acne scars (rolling scars and mild texture) and on dark marks left behind after spots heal, known as post-inflammatory hyperpigmentation.
- Deep icepick and boxcar scars rarely shift with a cream alone, but tretinoin can be a useful partner to procedures such as microneedling or subcision.
- Patience matters. Dark marks often start to fade within a few months, but collagen remodelling usually takes six to twelve months of steady use.
- Tretinoin needs a prescriber’s review, daily sunscreen, and a slow start. It isn’t suitable during pregnancy or when trying to conceive.
What is tretinoin, and why is it used for scars?
Tretinoin is the active, ready-to-use form of vitamin A, also known as all-trans retinoic acid. It belongs to a family of medicines called retinoids. You’ve probably heard of its gentler cousin, retinol, which pops up in countless serums on the high street.
Here’s the key difference. Your skin has to convert retinol into retinoic acid before it can do anything useful. That conversion is slow and patchy, so only a small fraction ends up working. Tretinoin skips the queue. It arrives already in its active form, which makes it much more powerful, and also explains why it’s prescription only in the UK.
Tretinoin was first developed to treat acne. Over the following decades, dermatologists noticed that people using it also had smoother texture, fewer fine lines and faded marks. That observation sparked years of research into tretinoin for scars, sun damage and uneven skin tone.
In the UK, licensed tretinoin mainly comes combined with an antibiotic in acne gels, such as clindamycin with tretinoin 0.025%. Prescribers can also arrange tretinoin on its own at a strength chosen for the individual, after a proper clinical assessment.
First, a quick guide to acne scars
Before we look at how tretinoin works, it helps to know what you’re dealing with. Not every mark on your face is a true scar, and that matters a lot for what treatment can achieve.
Atrophic acne scars
These are the most common type. They’re dips or hollows in the skin, caused when inflammation from a deep spot destroys collagen and the body doesn’t fully rebuild it. Think of a mattress that’s lost some of its stuffing in one spot. There are three main shapes:
Rolling scars
Wide, soft, wave-like dips that make the skin look uneven, especially under side lighting. These tend to respond best to tretinoin.
Boxcar scars
Round or oval dips with sharper edges, a bit like a chickenpox scar. Shallow ones may improve a little with tretinoin, while deeper ones usually need procedures.
Icepick scars
Narrow, deep channels that look like tiny puncture marks. A cream can’t really reach the bottom of these, so they almost always need specialist treatment.
Raised scars (hypertrophic and keloid)
These are the opposite problem: too much collagen rather than too little. They’re more common on the chest, back and jawline. Tretinoin isn’t a first-line treatment here, and these scars usually need a different approach, such as steroid treatment from a specialist.
Dark marks and red marks
Many people call these scars, but technically they’re not. Post-inflammatory hyperpigmentation (PIH) is the brown or dark patch left after a spot heals. It’s especially common in medium and deeper skin tones. Red or purple marks are called post-inflammatory erythema.
The good news? Dark marks are the area where tretinoin for scars often shows the quickest and most visible results, and research shows retinoids work well on hyperpigmentation across all skin tones.
How tretinoin works on scars: the science made simple
Here’s where it gets interesting. Tretinoin doesn’t sand your skin down or fill holes directly. Instead, it acts more like a site manager who turns up on a building project and gets everyone working properly again.
Step one: it sends new instructions to your skin cells
Once tretinoin soaks into your skin, it passes into your cells and binds to special receptors inside the cell nucleus, called retinoic acid receptors. These receptors act like switches on your DNA.
When tretinoin flips them, your skin cells change which genes they switch on and off. In plain terms, tretinoin changes the instructions your skin follows. That’s why it has such wide-ranging effects on both the surface and the deeper layers.
Step two: faster cell turnover at the surface
Your outer skin layer renews itself roughly every four to six weeks. As we get older, or after lots of inflammation, that process slows down. Old cells hang around, and the surface looks dull and uneven.
Tretinoin speeds up this conveyor belt. Fresh cells rise to the surface faster, and old, pigment-heavy cells shed sooner. It also affects how pigment is handed from pigment cells to skin cells. Together, that’s how tretinoin helps dark marks fade and gives skin a more even tone.
Step three: more collagen in the deeper layer
This is the part that really matters for true scars. Underneath the surface sits the dermis, your skin’s scaffolding. It’s made mostly of collagen, a tough protein that gives skin its firmness.
A landmark study found that people using tretinoin for about a year had measurably more new collagen forming in their skin than people using a dummy cream. More collagen means more stuffing in that mattress, which can gradually lift shallow dips.
Step four: less collagen breakdown
Your skin also makes enzymes called collagenases, which break collagen down. Inflammation and sunlight both ramp these up. Researchers have shown that tretinoin blocks some of the signals that switch these enzymes on.
So tretinoin works from both ends. It builds more collagen and protects what’s already there. Retinoids also appear to help reorganise newly formed collagen, which is important because scar tissue is often messy and disorganised.
Step five: fewer new scars in the first place
This is the most underrated benefit. Tretinoin is an acne treatment first and foremost. It keeps pores clearer and calms the inflammation that leads to new scars. A recent review concluded that topical retinoids can both improve the look of atrophic acne scars and slow the progression of scarring.
There’s no point repairing a wall if someone keeps kicking holes in it. Controlling active acne always comes first.
What does the evidence say about tretinoin for scars?
We believe in being honest, so here’s a fair summary.
The evidence for tretinoin on dark marks and sun-damaged skin is strong and backed by decades of research. The evidence for tretinoin for acne scars specifically is encouraging but based on smaller studies.
In one study of 35 people, a combination of retinoic acid and glycolic acid improved acne scars in most patients after 12 weeks. In studies where tretinoin was pushed deeper into the skin using a gentle electric current, a technique called iontophoresis, most patients had a noticeable reduction in scar depth after around three months.
Reviewers still agree that we need bigger, better trials of tretinoin for acne scars on its own. So we’d describe tretinoin as a sensible, evidence-informed part of scar care, rather than a miracle eraser.
Which scars respond best to tretinoin?
Here’s a realistic picture, based on the research and on the questions we hear at our Derby drop-in clinic.
Most likely to improve
- Dark marks (post-inflammatory hyperpigmentation)
- General roughness and uneven texture
- Shallow rolling scars
May improve a little
- Shallow boxcar scars
- Red marks left after spots, although these often fade on their own with time
Unlikely to improve with tretinoin alone
- Deep icepick scars
- Deep boxcar scars
- Raised hypertrophic or keloid scars
If most of your scars fall into the last group, don’t lose heart. Treatments such as microneedling, subcision, chemical peels and lasers can make a real difference. Tretinoin can still play a supporting role before or after these treatments, although your clinician will tell you when to pause it, as retinoids can make skin more sensitive around procedures.
It’s also worth knowing that the NHS doesn’t usually fund cosmetic treatment for acne scarring, so many people look at private options. NICE advises that people whose acne is causing scarring should be referred to a consultant dermatologist-led team, so if you still have active, scarring acne, speak to your GP too.
How long does tretinoin take to work on scars?
This is the question we’re asked most often. The honest answer is: longer than Instagram suggests.
Weeks 1 to 6: the adjustment phase
Your skin gets used to the medicine. Expect some dryness, flaking, tightness or redness. Some people get a short flare of spots, often called purging, as clogged pores clear out. This usually settles.
Months 2 to 4: dark marks begin to fade
Skin tone often looks more even and brighter. Dark marks start to soften. This is usually the first win people notice.
Months 6 to 12: texture starts to change
Collagen remodelling is slow work. Improvement in shallow scars tends to build gradually, which is why the key collagen research ran for around a year.
Think of it like a garden rather than a light switch. You won’t see the lawn thicken overnight, but look back at photos after six months and you may be pleasantly surprised. Take a photo in the same spot and lighting each month. Your mirror is a terrible judge of slow change.
How to use tretinoin for scars without the drama
Getting the routine right makes a huge difference to how well you tolerate tretinoin. Always follow your prescriber’s exact instructions, but here’s the general approach we explain to patients.
Start slow
Begin two or three nights a week, then build up to every night over several weeks if your skin is happy. Rushing is the main reason people give up.
Use less than you think
A pea-sized amount covers the whole face. The leaflet for licensed tretinoin gel describes dotting it on the chin, cheeks, nose and forehead, then spreading it gently. More product doesn’t mean faster results, just more irritation.
Apply to dry skin at night
Wash with a mild cleanser, pat dry, and wait 10 to 20 minutes. Damp skin absorbs more, which can sting. Keep it away from your eyes, lips and nostrils, and wash your hands afterwards.
Moisturise generously
A simple, fragrance-free moisturiser is your best friend. If your skin is sensitive, try the sandwich method: moisturiser, then tretinoin, then more moisturiser.
Wear sunscreen every single morning
Tretinoin makes your skin more sensitive to the sun, and sunlight can darken the very marks you’re trying to fade. Use a broad-spectrum SPF 30 or higher daily, even on grey British days. Yes, even in November.
Keep the rest of your routine simple
The prescribing information advises caution with drying products and peeling agents such as benzoyl peroxide, salicylic acid and harsh scrubs. Put the exfoliating toners and facial brushes away for now. Avoid waxing treated areas, too, as retinoid-treated skin can lift.
Side effects and who shouldn’t use tretinoin
Most side effects are local to the skin and ease as your skin adapts. The prescribing information lists dryness, redness, peeling, itching, burning and increased sun sensitivity among the reactions people may notice.
Tretinoin isn’t right for everyone. It’s not suitable if you’re pregnant, trying to conceive or breastfeeding, because retinoids can harm an unborn baby. It may also be unsuitable if you have eczema on your face, rosacea, sunburn or broken skin in the area.
That’s exactly why a proper assessment matters. A prescriber will check your skin type, medical history, previous reactions to skincare actives and other medicines before recommending anything.
Who can help you decide?
Scars can feel very personal. Some people barely notice theirs, while others avoid photos or bright bathroom lighting. Both reactions are completely valid.
At Courier Pharmacy, our pharmacist prescribers regularly talk people through their options for acne scars and dark marks. We’ll help you work out what type of scarring you have, whether tretinoin for scars is realistic for you, and when a referral for procedures might make more sense.
Frequently asked questions
Does tretinoin for scars really work?
For the right type of scar, yes. Tretinoin can help fade dark marks and soften shallow atrophic acne scars by boosting collagen production and speeding up cell turnover. It works less well on deep icepick or boxcar scars, which usually need procedures.
How long does tretinoin take to improve acne scars?
Dark marks often start to fade within two to four months. Changes in texture and shallow scars usually take six to twelve months of regular use.
Is tretinoin better than retinol for scars?
Tretinoin is stronger because it’s already in the active form your skin uses. Retinol has to be converted first, so it’s gentler but slower. Tretinoin is prescription only, while retinol is sold over the counter.
Can tretinoin remove old acne scars?
It can improve older shallow scars, but it’s unlikely to remove them completely. Scars that have been around for years are often firmer, so combining tretinoin with professional treatments tends to give better results.
Will tretinoin make my scars worse at first?
It won’t worsen true scars, but your skin may look red, dry or flaky for the first few weeks. Some people also get a temporary flare of spots. Starting slowly and moisturising well helps a lot.
Can I use tretinoin for scars on dark skin?
Yes, and it can be particularly helpful for dark marks in medium and deeper skin tones. Irritation can itself trigger new pigmentation, though, so a gentle start and daily sunscreen are especially important.
Can I use tretinoin with microneedling?
Tretinoin can support results from microneedling, but you’ll usually need to stop it for a few days before and after each session. Your clinician will tell you exactly when to pause and restart.
Does tretinoin help raised or keloid scars?
It’s not a first-line treatment for raised scars. These usually respond better to other options, such as steroid treatments from a specialist.
Do I need a prescription for tretinoin in the UK?
Yes. Tretinoin is a prescription-only medicine in the UK, so a prescriber needs to check it’s safe and suitable for you first.
What happens if I stop using tretinoin?
Collagen you’ve built doesn’t vanish overnight, but the ongoing benefits gradually wind down. Many people move to a lower strength or less frequent use for maintenance. Talk to your prescriber before stopping or changing treatment.
Disclaimer
Disclaimer: This information is for education only and isn’t a substitute for personal medical advice. Always follow your prescriber’s instructions.
References
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