What Are the Main Acne Scar Types? A Skin-Friendly Guide with Treatment Options

Struggling with acne's aftermath? This guide helps you identify your specific acne scar type, from indented ice pick to raised keloid scars, to explore commonly used treatment approaches for smoother-looking skin.

Important Notice: This article is for educational purposes only and does not constitute medical advice. Individual treatment plans should be developed in consultation with qualified healthcare professionals. Treatment outcomes vary from person to person, and no guarantee of results is intended or implied. All professional treatments mentioned should be performed by licensed medical practitioners in Singapore, using HSA-approved products, devices, and techniques, as applicable.

What Causes Acne Scars?

Acne scars are the lasting result of the skin's healing process after it has been damaged by inflammation. When an acne lesion, such as a papule, pustule, or cyst, forms, it creates significant inflammation within the dermis—the deeper layer of your skin. This inflammation can damage the skin's structural proteins, primarily collagen, and to a lesser extent elastin.

Collagen Production and Scar Formation

Collagen Response	Resulting Scar Category	Appearance
Too little collagen produced	Atrophic (Indented) Scars	Depressions or pits in the skin
Too much collagen produced	Hypertrophic & Keloid (Raised) Scars	Firm, raised tissue on the skin's surface

Note: The healing process and final appearance of scars vary depending on individual factors such as skin type and severity of acne.

The Main Categories of Acne Scars

Not all acne scars are created equal. After an acne lesion heals, the skin's repair process may sometimes result in irregular healing, leading to permanent textural changes. Acne scars are broadly classified into two main categories: atrophic scars, which result from tissue loss, and hypertrophic or keloid scars, which result from excess tissue formation.

• Atrophic Scars: Indented scars caused by a loss of tissue.

• Hypertrophic and Keloid Scars: Raised scars caused by an overgrowth of tissue.

Atrophic Scars

Atrophic scars are generally associated with lower collagen production during the healing process, which may lead to a reduction in supportive skin tissue. Common subtypes include ice pick, boxcar, and rolling scars.

Raised Scars

Raised scars are often linked to increased collagen production during the skin's healing response, which can result in firm, raised areas of scar tissue. These scars tend to be less frequent and are categorized as hypertrophic or keloid scars.

Summary of Acne Scar Categories

Feature	Indented (Atrophic) Scars	Raised (Hypertrophic/Keloid) Scars
Appearance	Depressed, pitted, or sunken into the skin.	Raised, firm, and lumpy above the skin's surface.
Underlying Cause	Net loss of collagen and tissue during healing.	Overproduction of collagen during healing.
Common Sub-types	Ice Pick, Boxcar, Rolling.	Hypertrophic, Keloid.

Common Indented Scars Explained

Indented, or atrophic, scars are generally a common type of acne scar. They form when there is a loss of tissue and collagen during the healing process, creating a depression or pit in the skin. These scars are further classified into three main subtypes based on their shape and depth.

Ice Pick Scars

Identifying Ice Pick Scars

Ice pick scars are deep, narrow pits that extend into the dermis. They look as though the skin has been punctured with a tiny, sharp object, giving them their name. These V-shaped scars are often smaller in diameter than other indented scars but are considered challenging to treat due to their depth.

Common Causes and Location

These scars typically result from severe inflammatory acne, such as cysts or papules that become infected deep within the pore. The infection destroys skin tissue, leaving a long, column-like scar. Ice pick scars are most frequently found on the cheeks.

Boxcar Scars

Identifying Boxcar Scars

Boxcar scars are broad, box-like depressions with sharply defined vertical edges. They can be shallow or deep and are typically round or oval. Their appearance is often compared to chickenpox scars. Unlike ice pick scars, they have a wider base and a more defined border.

Common Causes and Location

Boxcar scars form when an inflammatory breakout destroys collagen, leading to a localized loss of tissue. The skin in that area is left without its underlying support, causing it to sink. They commonly appear on areas such as the lower cheeks and jawline.

Rolling Scars

Identifying Rolling Scars

Rolling scars are wide depressions that have rounded, sloping edges. This creates an uneven, "rolling" or wave-like texture on the skin's surface. Unlike boxcar scars, their edges are not sharply defined, and they are typically wider than they are deep.

Common Causes and Location

These scars develop when fibrous bands(tight connective tissue strands) of tissue form between the skin's surface and the deeper subcutaneous tissue. These bands pull the epidermis down from within, tethering it to deeper structures and creating the undulating appearance. Rolling scars are most often seen on the lower cheeks and jaw.

Understanding the visual differences between these scars can help guide discussions with your healthcare provider about suitable treatment options. These causes are generally accepted in dermatology, but individual cases may vary. Please seek professional advice for accurate diagnosis. Here is a quick comparison:

Summary of Indented Acne Scar Types

Scar Type	Appearance	Key Characteristics
Ice Pick	Deep, narrow, V-shaped pits	Looks like a puncture; extends deep into the dermis.
Boxcar	Round or oval depressions with sharp, vertical edges	Crater-like appearance; can be shallow or deep.
Rolling	Broad depressions with sloping, undefined edges	Creates a wave-like or uneven skin texture.

Common Raised Scars Explained

While indented scars are caused by a loss of tissue, raised scars occur when the body produces too much collagen during the healing process. These scars, also known as hypertrophic scars, sit above the surface of the surrounding skin. They are less common than atrophic acne scars and are more frequently found on the torso, particularly the chest and back.

Hypertrophic Scars

A hypertrophic scar is a thick, raised scar that forms directly at the site of a healed acne lesion. When your skin is injured, it produces collagen fibers to repair the damage. In some cases, the body produces an excess amount of collagen, leading to a raised lump of scar tissue. A key characteristic of a hypertrophic scar is that it remains confined within the boundaries of the original pimple or cyst. They often appear on the jawline, chest, back, and shoulders and can be pink or red in color and sometimes itchy.

Keloid Scars

Keloid scars are a more persistent and expansive type of raised scar. Like hypertrophic scars, they result from an overproduction of collagen. However, unlike hypertrophic scars, keloids extend beyond the initial wound area and continue to grow over time. They may gradually enlarge beyond the size of the initial acne lesion and may appear as smooth, firm, rubbery growths that can be pink, red, or dark brown. Keloids can be itchy or painful and are thought to be more common in individuals with a genetic predisposition. Some studies suggest a higher prevalence among individuals with darker skin tones.

How to Tell Hypertrophic and Keloid Scars Apart

Understanding the differences between these two types of scars is important as treatment approaches may vary. While a doctor's diagnosis is always best, the table below highlights their main differences.

Comparison of Hypertrophic and Keloid Scars

Feature	Hypertrophic Scars	Keloid Scars
Growth Pattern	Remains within the boundaries of the original acne lesion.	Grows beyond the boundaries of the original wound, invading healthy skin.
Size	The size of the scar matches the size of the initial pimple or cyst.	Can become significantly larger than the initial acne lesion over time.
Prevalence	More common than keloids. Can affect anyone.	Less common. Strong genetic link, more prevalent in skin of color.
Symptoms	Can be firm and may be slightly itchy.	Often firm or rubbery and can be itchy, tender, or painful.
Progression	May flatten and become less noticeable on their own over several months or years.	Rarely regress without treatment and may continue to grow slowly.

Skin Discoloration Often Confused with Scarring

After a pimple heals, you might notice a flat spot of discoloration left behind. While frustrating, these marks are not true acne scars because they don't involve a change in your skin's texture. Unlike atrophic or hypertrophic scars, these spots are temporary and often fade over time. They are a result of the skin's inflammatory response to the original acne lesion.

Understanding the difference is key, as the treatment for discoloration differs from the treatment for textured scars. The two main types of post-acne discoloration are Post-Inflammatory Hyperpigmentation (PIH) and Post-Inflammatory Erythema (PIE).

Post-Inflammatory Hyperpigmentation (PIH)

Post-Inflammatory Hyperpigmentation appears as flat brown, black, or tan spots on the skin where an acne lesion once was. This occurs when inflammation from acne triggers an overproduction of melanin, the pigment that gives skin its color. PIH may manifest differently across various skin types. These dark spots can linger for months or even years if left untreated, but they are not permanent.

Post-Inflammatory Erythema (PIE)

Post-Inflammatory Erythema presents as Flat red, pink, or purple spots. PIE is a vascular issue caused by the damage or dilation of tiny blood vessels (capillaries) near the skin's surface during an inflammatory acne breakout. PIE may manifest differently across various skin types. A simple way to test for PIE is the "blanch test": if you press on the spot gently, it may temporarily turn white before the redness returns.

PIH vs. PIE: Key Differences

Feature	Post-Inflammatory Hyperpigmentation (PIH)	Post-Inflammatory Erythema (PIE)
Appearance	Flat brown, black, or tan spots.	Flat red, pink, or purple spots.
Primary Cause	Overproduction of melanin (pigment).	Damage or dilation of blood vessels (capillaries).
Commonly Affects	More prevalent and noticeable in darker skin tones.	More prevalent and noticeable in lighter skin tones.
Texture	Smooth and flat, no change in skin texture.	Smooth and flat, no change in skin texture.

Professional Treatment Options for Acne Scars

While at-home skincare may help improve skin texture, significant acne scars may benefit from professional evaluation and treatment options that a qualified doctor can discuss with you.These treatments work through various mechanisms and results may vary between individuals. A qualified doctor can explain the specific approach suitable for your condition. The best approach depends on your specific scar types, skin tone, and treatment goals.

Treatments for Common Indented Scars (Atrophic Scars)

Treatments for atrophic scars focus on stimulating collagen production to raise the indented scar floor, helping to smooth the skin's surface. Combining therapies may enhance treatment outcomes, depending on individual response.

Laser Resurfacing

Laser resurfacing uses focused light energy and may help improve skin texture. There are two main types:

• Ablative Lasers: These laser treatments involve removing surface skin layers. Treatment options, their suitability, and recovery times vary significantly between individuals and should be discussed with a qualified practitioner.

• Non-Ablative Lasers: These laser treatments work on deeper skin layers without removing the surface. Individual treatment plans and recovery experiences vary and should be discussed with a qualified practitioner.

Microneedling

Also known as collagen induction therapy, microneedling involves a device with fine, tiny needles that creates controlled micro-injuries in the skin. This process triggers the body's natural wound-healing response, boosting the production of collagen and elastin. It may be particularly helpful for treating shallow boxcar and rolling scars.

Dermal Fillers

For certain types of indented scars, a doctor can inject dermal fillers (such as those containing hyaluronic acid) directly beneath the scar. This procedure physically lifts the depressed area to make it level with the surrounding skin. Results vary significantly between individuals in both appearance and duration. Your doctor can discuss realistic expectations based on your specific condition.

Chemical Peels

Chemical peels performed by trained professionals use stronger formulations than over-the-counter products, which may lead to more noticeable exfoliation. This deep exfoliation may promote skin renewal and help reduce the appearance of superficial atrophic scars over time.

Subcision

Subcision is a minor surgical procedure that may be suitable for certain types of rolling scars. A doctor inserts a special hypodermic needle horizontally into the skin to break up the tough, fibrous bands that are tethering the scar base to the deeper tissue. Releasing these bands allows the skin to lift and smooth out.

TCA CROSS Method

The TCA CROSS method is a targeted technique used for treating deep ice pick and narrow boxcar scars. It involves the precise application of a high-concentration TCA directly onto the scar floor. This causes a localized inflammatory reaction that stimulates collagen synthesis, gradually raising the base of the scar.

Summary of Treatments for Indented (Atrophic) Scars

Treatment	Commonly Used For	Key Consideration
Laser Resurfacing	Boxcar, Rolling Scars	Ablative lasers are effective but involve significant downtime.
Microneedling	Shallow Boxcar & Rolling Scars	Multiple sessions are required for optimal results.
Dermal Fillers	Rolling Scars, some Boxcar	Provides immediate but temporary improvement.
Chemical Peels	Superficial Scars	Requires professional-strength formulas for scar revision.
Subcision	Tethered Rolling Scars	Physically breaks the fibrous bands pulling the scar down.
TCA CROSS	Ice Pick Scars, narrow Boxcar	A highly targeted application of acid to rebuild the scar floor.

Treatments for Common Raised Scars (Hypertrophic and Keloid Scars)

The goal for treating raised scars is to reduce excess collagen, flatten the tissue, and alleviate symptoms like itching or pain.

Corticosteroid Injections

Injecting corticosteroids directly into hypertrophic or keloid scars is a commonly used first-line treatment. It may help reduce inflammation and soften raised tissue over a series of sessions. The steroids break down the excess collagen fibers and reduce inflammation, causing the scar to soften and flatten over a series of treatments.

Silicone Gels and Sheets

Medical-grade silicone gels and sheets are a non-invasive option, often used for newer hypertrophic scars. They are believed to help hydrate the tissue and regulate fibroblast activity when used consistently over time. They work by hydrating the scar tissue, regulating fibroblast activity, and reducing collagen production. Consistent, long-term use is necessary to see results.

Cryotherapy

Cryotherapy involves freezing the scar tissue with liquid nitrogen. This process may damage scar cells and restrict blood supply, which could help reduce its size and flatten the tissue over time. This treatment is often used for smaller, firm keloids and may be combined with corticosteroid injections for enhanced effectiveness.

Summary of Treatments for Raised (Hypertrophic & Keloid) Scars

Treatment	Commonly Used For	Key Consideration
Corticosteroid Injections	Hypertrophic & Keloid Scars	A clinical treatment option that may be considered; individual results vary with repeated sessions.
Silicone Gels and Sheets	Hypertrophic Scars, Mild Keloids	A non-invasive option that may support scar care with consistent and prolonged use.
Cryotherapy	Small, Firm Keloids	May assist in the management of certain keloid scars; consult a healthcare provider for suitability.

Skincare Tips for Smoother Skin at Home

While professional treatments deliver the most significant results for acne scars, a consistent at-home skincare routine is crucial for supporting skin health and improving overall texture. Certain ingredients may help support the appearance of discoloration, skin texture, and reduce the risk of breakouts that could lead to more scarring.

Topical Retinoids like Tretinoin and Adapalene

Topical retinoids are widely used in dermatology for managing acne and scarring. They work by accelerating skin cell turnover and boosting collagen production. This dual action helps to unclog pores, which prevents new acne from forming, and gradually smooths the skin's surface, which can diminish the appearance of shallow atrophic scars—depressed or sunken scars caused by loss of skin tissue—and discoloration over time.

• Prescription Retinoids: Prescription-strength retinoids are available and should be discussed with a qualified healthcare provider who can assess their suitability for your specific condition.

• Over-the-Counter (OTC) Retinoids: Some topical treatments may be available without prescription. Please consult a pharmacist or healthcare provider for current availability and suitability.

When incorporating retinoids, it's important to start slowly (2-3 times per week) and apply only at night to clean, dry skin. Always follow with a moisturizer and use sunscreen diligently every morning, as retinoids can increase sun sensitivity.

Alpha Hydroxy Acids (AHAs) and Beta Hydroxy Acids (BHAs)

AHAs and BHAs help promote skin cell turnover and improve surface texture, promoting a brighter and smoother complexion. They are gentler than harsh physical scrubs and can effectively address concerns related to scarring, such as uneven texture and discoloration.

AHA vs. BHA for Skin Texture

Feature	Alpha Hydroxy Acids (AHAs)	Beta Hydroxy Acids (BHAs)
Common Examples	Glycolic Acid, Lactic Acid, Mandelic Acid	Salicylic Acid
How They Work	Water-soluble. They work on the skin's surface to exfoliate dead skin cells.	Oil-soluble. They penetrate deeper into pores to clear out oil and debris.
Commonly Used For	Improving surface texture, fading post-inflammatory hyperpigmentation (PIH), and smoothing fine lines.	Treating active acne, blackheads, and whiteheads. Also effective for reducing inflammation.
Scar Application	May help improve the appearance of shallow scars and discoloration by promoting a more even skin tone.	Primarily may help prevent future scarring by treating active acne. It may also help reduce associated inflammation and redness.

The Importance of Sunscreen for Scar Healing

Sun protection is an important step in skincare routines, particularly for supporting the healing process of acne scars. UV radiation from the sun may slow the healing process and potentially worsen the appearance of scars in two key ways:

• Darkening Discoloration: Sun exposure triggers melanin production, which can cause post-inflammatory hyperpigmentation (PIH), a condition where the skin develops dark spots after inflammation, to become much darker and more persistent.

• Collagen Degradation: UV rays break down existing collagen in the skin, undermining the very foundation your body is trying to rebuild to fill in atrophic scars.

To protect your skin and support scar healing, make a habit of applying a broad-spectrum sunscreen with an SPF of 30 or higher every single day, even when it's cloudy. Reapply every two hours when outdoors. For sensitive or acne-prone skin, consider a mineral-based sunscreen containing zinc oxide or titanium dioxide, as they are often less irritating.

How to Prevent Future Acne Scars

While treatments can significantly improve the appearance of existing scars, prevention is always the most effective strategy. Protecting your skin during an active breakout is the key to avoiding permanent marks. Here are the most crucial steps to prevent acne scars from forming.

Stop Picking or Popping Pimples

It can be tempting, but picking, squeezing, or popping pimples is one of the main causes of acne scarring. This action can force bacteria and pus deeper into the dermis, increasing inflammation and tissue damage. It also introduces new bacteria from your fingers, which can lead to infection and more severe lesions. Disrupting the natural healing process by picking at a blemish dramatically raises the risk of damaging collagen and elastin, resulting in a permanent atrophic or hypertrophic scar.

Instead of picking, consider these alternatives:

• Apply a spot treatment: Use products containing salicylic acid or benzoyl peroxide to help reduce the pimple's size and inflammation.

• Use a hydrocolloid patch: These "pimple patches" create a moist, protected environment that may help absorb fluid from the blemish, reduce inflammation, and act as a physical barrier to prevent you from touching it. Results may vary by individual.

Treat Active Acne Early

The longer and more severe the inflammation, the higher the likelihood of scarring. Early treatment of acne can help reduce the risk of skin damage. Early intervention can shorten the duration and lessen the severity of breakouts, particularly for more severe forms like cystic acne and nodular acne, which occur deep within the skin and are most likely to leave scars.

If over-the-counter products are not controlling your breakouts, consult a doctor. A doctor can prescribe stronger topical or oral medications to help manage inflammation, which may reduce the risk of future scarring.

Adopt a Gentle Skincare Routine

Aggressive scrubbing and harsh skincare products can irritate your skin, compromise its protective barrier, and worsen inflammation. A gentle, consistent routine supports your skin's healing process and helps prevent the irritation that can contribute to scarring. Focus on cleansing, moisturizing, and protecting your skin without stripping it of its natural oils.

Gentle Skincare Practices

Do	Don't
Use a mild, pH-balanced cleanser twice daily.	Use harsh physical scrubs or abrasive cleansing tools on active breakouts.
Gently pat your skin dry with a soft, clean towel.	Rub your skin aggressively with a towel.
Apply a non-comedogenic moisturizer to keep the skin barrier healthy.	Over-exfoliate with high-strength chemical exfoliants, which can cause irritation.
Wear broad-spectrum sunscreen with an SPF of 30 or higher every day.	Consider avoiding products with high amounts of drying alcohols, as they may cause irritation in some individuals.

When to Consult a Board-Certified Doctor

While at-home skincare can improve skin texture and mild discoloration, professional intervention is essential for treating established acne scars effectively. A qualified medical practitioner can provide an assessment and discuss treatment options suitable for your specific condition. Relying on self-diagnosis can lead to ineffective treatments or even worsen your skin's appearance.

Consulting a professional can help you explore clinically validated treatments that are more likely to address your specific skin concerns effectively and safely. Consider making an appointment if you experience any of the following situations.

Key Indicators for Professional Consultation

Signs You Should See a Doctor	Why It's Important
Over-the-counter (OTC) products are not working.	If topical treatments have not improved your scars after several months, a doctor may offer treatments such as laser therapy, chemical peels, or microneedling, which are clinically administered and tailored to deeper skin concerns.
You have deep indented scars (ice pick, boxcar).	These atrophic scars often benefit from procedures such as TCA CROSS, subcision, or dermal fillers, depending on individual assessment.
You have raised scars (hypertrophic or keloid).	These scars may be addressed through medical treatments such as corticosteroid injections, cryotherapy, or silicone-based therapies, depending on their severity.
Your scars are causing emotional distress.	The impact of acne scars on self-esteem and mental health is a valid medical concern. A doctor can recommend treatment options that may help improve your skin concerns and support your overall well-being.
You are unsure what type of scars you have.	An accurate diagnosis is critical. A professional can assess whether you have atrophic scars, hypertrophic scars, or discoloration such as PIH or PIE, and recommend suitable treatment options accordingly.
You still have active, inflammatory acne.	Controlling active acne is the first step to preventing new scars. A doctor can prescribe effective treatments to manage breakouts while planning for future scar revision.

Summary

Navigating the world of acne scars can be complex, but understanding the specific type you have is the crucial first step toward exploring appropriate treatment options. Acne scars are primarily categorized based on whether they cause an indentation in the skin (atrophic) or create raised tissue (hypertrophic). It is also important to distinguish these true scars from skin discoloration, such as post-inflammatory hyperpigmentation (PIH) and post-inflammatory erythema (PIE), which are not permanent changes in skin texture.

This table provides a quick reference to the main types of acne scars and common forms of discoloration:

Scar or Discoloration Type	Key Characteristics	Main Category
Ice Pick Scars	Deep, narrow, V-shaped pits that look like they were made by a sharp object.	Atrophic (Indented)
Boxcar Scars	Broad, box-like depressions with sharply defined, vertical edges.	Atrophic (Indented)
Rolling Scars	Wide depressions with sloping, undefined edges, giving the skin a wavy appearance.	Atrophic (Indented)
Hypertrophic Scars	Raised, firm bumps of scar tissue that remain within the boundaries of the original acne lesion.	Raised
Keloid Scars	Raised scar tissue that grows beyond the original wound's borders, often larger than the initial pimple.	Raised
Post-Inflammatory Hyperpigmentation (PIH)	Flat brown, black, or gray spots of discoloration left after inflammation. Not a true scar.	Discoloration
Post-Inflammatory Erythema (PIE)	Flat red, pink, or purple spots caused by damage to small blood vessels. Not a true scar.	Discoloration

Treatment options vary depending on the scar type. Indented scars may be managed with professional procedures such as laser resurfacing, microneedling, or dermal fillers, subject to individual medical assessment and availability. In contrast, raised scars may be managed with treatments including corticosteroid injections, silicone sheets, or cryotherapy, as advised by a qualified medical professional. At-home care, including topical retinoids, exfoliating acids, and daily sunscreen use, can support professional treatments and improve overall skin texture.

Ultimately, preventing future scars by timely treatment of active acne and avoiding picking is an important strategy. For an accurate diagnosis and a personalized treatment plan, it is essential to consult a qualified doctor registered with the Singapore Medical Council who can recommend appropriate and safe options for your skin.

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Note: This article is for educational purposes only and does not constitute medical advice. Individual treatment plans should be developed in consultation with qualified healthcare professionals. Treatment outcomes vary from person to person, and no guarantee of results is intended or implied. All professional treatments mentioned should be performed by licensed medical practitioners in Singapore, using HSA-approved products, devices, and techniques, as applicable.