Acne scars form when inflamed breakouts damage the skin’s deeper layers, disrupting normal collagen production during healing. The main types are atrophic (depressed) scars — including ice pick, boxcar, and rolling scars — plus raised hypertrophic and keloid scars. Each type looks different and responds best to different treatments.
What Are Acne Scars and How Do They Form?
Acne scars are permanent changes in skin texture that form when inflamed acne damages the deeper layers of skin during the healing process. Unlike temporary marks, true scars involve a change in the skin’s structure — either a loss of tissue (depressed scars) or an overproduction of tissue (raised scars).
The Skin’s Healing Response to Acne
When a breakout damages skin deep enough to affect collagen, the body tries to repair it. If it produces too little collagen, the skin sinks in, forming a depressed scar. If it produces too much, the skin raises, forming a hypertrophic or keloid scar.
Why Some Acne Leaves Scars and Some Doesn’t
Mild acne that stays close to the skin’s surface usually heals without scarring. Scarring is more likely when a breakout is deep, inflamed, or infected, and when it’s picked at or left untreated for too long.
Which Types of Acne Are Most Likely to Scar
Cystic and nodular acne carry the highest risk of scarring since they cause deep, prolonged inflammation. Surface-level whiteheads and blackheads rarely scar unless they’re repeatedly irritated or picked.
Types of Acne Scars
There are two main categories of acne scars: atrophic (depressed) scars, which include ice pick, boxcar, and rolling scars, and raised scars, which include hypertrophic and keloid scars.
Atrophic (Depressed) Scars
Atrophic scars form when the skin doesn’t produce enough collagen during healing, leaving an indentation. They’re the most common type of acne scar and include three subtypes based on shape.
Ice Pick Scars Ice pick scars are narrow, deep, V-shaped indentations that go straight down into the skin, often resembling a small puncture. They’re among the hardest scars to treat because of their depth.
Boxcar Scars Boxcar scars are wider, box-shaped indentations with sharply defined edges, similar to chickenpox scars. They can be shallow or deep and typically appear on the cheeks and temples.
Rolling Scars Rolling scars have sloped, wave-like edges that create a rolling texture across the skin. They’re caused by fibrous bands pulling the skin down from beneath the surface.
Hypertrophic Scars
Hypertrophic scars are raised, thickened areas of scar tissue that stay within the original boundary of the breakout. They form when the skin overproduces collagen while healing.
Keloid Scars
Keloid scars are raised scars that grow beyond the original wound’s boundary, sometimes becoming larger than the acne lesion that caused them. They’re more common in people with a genetic tendency toward keloid formation.
Acne Scars vs Post-Inflammatory Marks (PIH & PIE)
True acne scars involve a permanent change in skin texture, while post-inflammatory marks — hyperpigmentation (dark spots) and erythema (red marks) — are flat, temporary discoloration left behind after a breakout heals.
Post-Inflammatory Hyperpigmentation (Dark Spots)
Post-inflammatory hyperpigmentation (PIH) is a flat, darkened patch of skin that appears after a breakout heals, caused by excess melanin production. It’s more common and more pronounced in darker skin tones.
Post-Inflammatory Erythema (Red Marks)
Post-inflammatory erythema (PIE) is a flat, pink or red mark left behind after a breakout, caused by damaged or dilated blood vessels near the skin’s surface. It’s more visible in lighter skin tones.
How to Tell True Scars from Temporary Marks
The simplest way to tell them apart is texture: run a finger over the area with eyes closed. If the skin feels smooth but discolored, it’s PIH or PIE and will likely fade on its own. If there’s a noticeable dip or raised bump, it’s a true scar that won’t resolve without treatment.
What Causes Acne Scarring?
Acne scarring is most often caused by deep or cystic acne, picking or squeezing breakouts, delayed treatment, and individual genetics or skin type.
Deep or Cystic Acne
Cystic acne causes intense, prolonged inflammation deep in the skin, making it far more likely to damage collagen and leave a lasting scar compared to surface-level breakouts.
Picking or Squeezing Breakouts
Picking or squeezing a breakout increases inflammation and can push infection deeper into the skin, significantly raising the risk of scarring compared to leaving it untouched.
Delayed or Inadequate Acne Treatment
The longer active acne goes untreated, the more time it has to cause deeper tissue damage, so early, consistent treatment reduces the likelihood of scarring.
Genetics and Skin Type
Some people are simply more prone to scarring than others due to genetics, including a higher likelihood of hypertrophic or keloid scar formation, regardless of how the acne is managed.
How Each Type of Acne Scar Is Treated
Different acne scar types respond to different treatments — deeper, narrower scars generally need more intensive procedures, while raised scars respond best to treatments that flatten and soften tissue.
Best Treatments for Ice Pick Scars
Because they’re deep and narrow, ice pick scars typically respond best to TCA CROSS treatment or punch excision, sometimes combined with laser resurfacing for further improvement.
Best Treatments for Boxcar Scars
Boxcar scars often respond well to fractional laser resurfacing, chemical peels, and dermal fillers, which help soften their sharply defined edges.
Best Treatments for Rolling Scars
Rolling scars typically respond best to subcision, which releases the fibrous bands pulling the skin down, often combined with microneedling or laser treatment for added improvement.
Best Treatments for Hypertrophic and Keloid Scars
Raised scars are usually treated with steroid injections to flatten tissue, along with laser therapy or, in some cases, surgical revision for larger keloids.
Treatment Options for Acne Scars
Common acne scar treatments include fractional CO2 laser, microneedling, chemical peels, subcision, dermal fillers, and steroid injections — with the right choice depending on scar type and severity.
Fractional CO2 Laser
Fractional CO2 laser resurfaces the skin and stimulates deep collagen production, making it effective for boxcar and rolling scars, and often combined with other treatments for a fuller result.
Microneedling
Microneedling creates controlled micro-injuries that stimulate collagen production, gradually improving the appearance of shallow to moderate scars with minimal downtime.
Chemical Peels
Chemical peels exfoliate the skin’s surface and can improve mild scarring and overall texture, though they’re generally less effective than laser or subcision for deeper scars.
Subcision
Subcision uses a needle to break up the fibrous bands tethering rolling scars to deeper tissue, allowing the skin to lift and smooth out over time.
Dermal Fillers
Dermal fillers can be injected beneath boxcar or rolling scars to physically lift the depressed area, offering a temporary but immediate improvement in appearance.
Steroid Injections (for Raised Scars)
Steroid injections are used specifically for hypertrophic and keloid scars, helping to flatten and soften raised tissue over a series of sessions.
Frequently Asked Questions
What is the most common type of acne scar?
Boxcar scars and rolling scars are generally the most common types of atrophic acne scars, though most people with a history of acne have a mix of different scar types.
Can acne scars go away on their own?
True acne scars don’t fully go away on their own, since they involve a structural change in the skin. Post-inflammatory marks (PIH and PIE), on the other hand, typically fade naturally over several months.
Which acne scars are hardest to treat?
Ice pick scars are generally the hardest to treat because of how deep and narrow they are, often requiring more intensive procedures like TCA CROSS or punch excision.
Is post-inflammatory hyperpigmentation a permanent scar?
No, post-inflammatory hyperpigmentation is not a true scar — it’s a temporary discoloration that usually fades on its own within several months to a year, though it can be slower to resolve in darker skin tones.
How many treatment sessions are needed?
Most acne scar treatments require multiple sessions — often 3 to 6 — spaced weeks apart, with the exact number depending on scar type, severity, and the treatment method used.
