Understanding Acne Scars: Types, Causes, and Treatment Options

Scarring occurs when acne inflammation is severe enough to damage the dermis, the deeper layer of skin beneath the epidermis. When a deep spot or cyst ruptures, it triggers an inflammatory response and sets off the skin's healing process. If that process produces too little collagen, the result is a depressed (atrophic) scar. If it produces too much, the result is a raised (hypertrophic or keloid) scar.

The risk of scarring is higher with inflammatory acne, nodules and cysts that extend deep into the dermis, and increases with delayed or inadequate treatment. Picking and squeezing spots also significantly raises the risk, as mechanical trauma extends the dermal injury and increases inflammation. This is why controlling active acne is always the first priority before addressing scarring: treating scars while new lesions are forming is unlikely to produce lasting results.

Atrophic scars, those that sit below the surrounding skin surface, are the most common type from acne. They are further divided into three subtypes based on their shape, depth, and width. Ice pick scars are narrow and deep, with a V-shaped cross-section. They are the most difficult to treat because they extend deep into the dermis and sometimes into the subcutaneous tissue. Boxcar scars are round or oval with well-defined vertical edges and a flat base, similar in appearance to chickenpox scars. Rolling scars have a wavy, undulating surface caused by fibrous tissue bands tethering the skin to deeper structures below.

Most patients have a combination of subtypes, and treatment is often tailored to address the predominant pattern. An accurate scar assessment, ideally under magnification and in raking light, is essential for selecting the right approach.

Dark marks left after acne spots are often called scars, but in most cases they are post-inflammatory hyperpigmentation (PIH), temporary discolouration caused by melanin overproduction during inflammation. PIH is common in medium to darker skin tones and can persist for months, but it eventually fades without treatment. Brightening treatments, chemical peels, and sun protection can speed this process.

True atrophic or textural scars, by contrast, represent a permanent structural change in the dermis that will not resolve on its own. Distinguishing between PIH and actual scarring matters, because the treatments are different.

Fractional laser resurfacing is the most widely used and best-evidenced treatment for atrophic acne scars. By creating controlled columns of thermal injury in the dermis, it stimulates collagen remodelling and gradually improves the scar's depth and texture over a course of sessions. Boxcar and rolling scars typically respond better than ice pick scars, which may require additional approaches such as punch excision or subcision.

Chemical peels can improve superficial scarring and post-inflammatory pigmentation, particularly in patients with milder scarring or as a complement to laser treatment. They are generally not effective for deep atrophic scars on their own.

The SCAR Protocol, offered at the clinic, combines fractional laser with exosome therapy in a single session. Exosomes are cell-derived nanoparticles rich in growth factors and signalling molecules that support tissue regeneration. The rationale for combining them with laser is to enhance collagen production and reduce the inflammatory phase of recovery, potentially improving outcomes in patients with deep or treatment-resistant scarring.

There is no universal answer. The number of sessions depends on the scar type and severity, the patient's skin tone, the type of laser used, and how the individual's skin responds to treatment. As a general guide, mild to moderate scarring may show meaningful improvement after three to four sessions; deeper or more widespread scarring may require five or more.

Results continue to improve for three to six months after each session as collagen remodelling progresses, so assessments are best made at least three months after the most recent treatment. Patience, realistic expectations, and a consistent treatment plan give the best outcomes.