Guide cluster: SMP

SMP for Scars

Quick answer: SMP is not a hair transplant. It creates the look of tiny shaved hairs using pigment in the scalp. It can help with scars, diffuse thinning, failed transplants, or cases where surgery is not a good fit.

The Scalp Scar Nobody Warned You About — and What SMP Can Do

Scalp scars come from many sources: the linear incision of a FUT hair transplant, the hundreds of small circular marks left by FUE extraction, a childhood injury, a burn, or surgery to the skull itself. What they share is a quality that makes them cosmetically difficult: they do not grow hair, and they often stand out in stark contrast against the surrounding scalp, particularly at short hair lengths. Scalp micropigmentation has emerged as the most consistently effective cosmetic intervention for this problem — not because it restores hair growth in scars, but because it is exceptionally well suited to the specific task of making scars visually disappear at the scale at which the human eye processes the scalp.

What Types of Scars SMP Can Address

The range of scalp scarring that responds to SMP is broader than many people realise. The most commonly treated category is transplant-related scarring: the horizontal linear scar left by FUT strip harvesting, and the distributed pattern of small circular depigmented marks left by FUE punch extraction [1]. Both respond well to SMP, though the technique varies between them — FUT scars require blending a continuous strip, while FUE donor-area scarring requires working across a diffuse field of individual marks.

Beyond transplant scarring, SMP is used for trauma scars resulting from accidents, injuries, or surgery unrelated to hair restoration. Post-craniotomy scarring — scarring on the scalp following brain surgery — represents one of the more medically significant applications, and clinical evidence supports its use in this context [2]. Patients who have undergone skull surgery and wish to conceal the resulting scar at comfortable hair lengths are increasingly turning to SMP as a safe, effective option.

Burn scars affecting the scalp present a more variable scenario. Where the burn has produced flat, stable, fully healed scarring with relatively uniform texture, SMP can be highly effective. Where the burn has produced raised, hypertrophic, or keloid scarring, the approach becomes more complex — raised scars require different or additional interventions before SMP is likely to produce satisfactory results [3].

Scarring alopecia — hair loss resulting from inflammatory or autoimmune scalp conditions that destroy the follicular unit and leave scar tissue — is also an emerging application. Clinical studies have evaluated SMP specifically in this context, finding both good efficacy and patient satisfaction [1].

How SMP Works on Scar Tissue

Scar tissue is fundamentally different from normal scalp skin. It is composed primarily of collagen fibres laid down rapidly during the wound-healing process, resulting in a denser, less flexible tissue with reduced vascularity compared to the surrounding skin [4]. Hair follicles are absent. The surface texture may differ from normal skin — smoother, shinier, or conversely more irregular, depending on the type and age of the scar.

These differences affect how SMP pigment behaves in scar tissue. In some cases, the denser fibrous structure causes pigment to spread slightly from the point of deposition, producing dots with less defined edges than on normal skin. In other cases, particularly in very old, tough scar tissue, pigment retention can be less reliable, with greater than average fading between sessions [3]. In both scenarios, the response underscores the need for a practitioner with direct experience performing SMP on scar tissue — not simply a practitioner who is proficient in standard scalp SMP.

The needle depth, dot size, and pigment concentration used in scar SMP may all need to be adjusted compared to non-scar applications. An experienced scar-SMP practitioner will typically use conservative dot sizing in the first session to assess the tissue response before committing to a specific approach [2].

What Results Are Realistic

For FUT linear scars, SMP routinely produces outcomes that dramatically reduce the visibility of the scar at short and shaved hair lengths. Patients who previously could not wear their hair below a minimum guard length without the scar becoming visible are typically able to wear their hair at any length after SMP [1]. The scar does not disappear literally — it is still there — but the pigment across it creates sufficient visual noise to blend with the surrounding scalp in normal daily observation.

For FUE donor-area marking, results are typically good to excellent, with the distributed pattern of small circles replaced by an impression of uniform donor-area density [3]. The degree of improvement depends on the extent of the marking and the patient's skin tone.

For trauma scars and post-surgical scars, clinical data from post-craniotomy cases support the conclusion that SMP produces good aesthetic outcomes and high patient satisfaction when performed on stable, flat scar tissue [2]. The caveat is that stability is important: SMP should not be performed on scars that are still changing in colour, texture, or size, which typically means waiting at least twelve to eighteen months after the initial injury or surgery before proceeding.

For raised or hypertrophic scars, results are more modest and less predictable. Elevated scar tissue presents technical challenges for dot placement and retention, and may benefit from treatment with fractional laser or silicone scar therapy before SMP is attempted [3].

Scar SMP vs. Hair Transplant into Scars

A question that sometimes arises is whether hair transplant into scar tissue is a viable alternative to SMP for camouflage. The answer, in most cases, is that it is not — at least not as a primary or standalone strategy. Scar tissue, particularly well-established fibrous scar tissue, has noticeably reduced vascularity compared to normal scalp tissue [4]. Hair follicles require an adequate blood supply to survive and grow in their new location. In the fibrous, avascular environment of mature scar tissue, graft survival rates are typically much lower than in normal scalp tissue, and results are often patchy or insufficient.

SMP does not face this limitation. The pigment deposition process does not depend on blood supply in the recipient tissue — it relies only on the mechanical integration of pigment particles into the dermal layer, a process that works in scar tissue even when vascularity is poor [1]. This fundamental difference makes SMP the more reliable choice for scar camouflage in most cases, while hair transplant into scars remains an option only in specific scenarios where the scar tissue has been pretreated or is in favourable condition.

Key Takeaways

• SMP addresses FUT linear scars, FUE donor-area marks, trauma scars, burn scars, and post-surgical scars including post-craniotomy [2][3].
• SMP creates visual camouflage in scar tissue — it does not physically restore hair or alter scar structure [1].
• Scar tissue absorbs pigment differently; experienced scar-SMP practitioners adjust technique accordingly — dot size, depth, and pigment concentration may all differ from standard scalp SMP [3].
• Best results are on flat, stable scars; raised or hypertrophic scars may need prior treatment before SMP [3].
• Hair transplant into mature scar tissue typically yields poor results due to reduced vascularity; SMP does not depend on recipient tissue vascularity and is so more reliable for scar camouflage [4].
• Typical session count for scar camouflage is 2–4; improvement is visible from session two onward [1].

References

[1] Shubham M, et al. (2025). SMP efficacy and safety in scarring alopecia. Journal of Cutaneous and Aesthetic Surgery. Doi: 10.25259/jcas_97_2025. https://doi.org/10.25259/jcas_97_2025

[2] Xu J, et al. (2025). Scalp micropigmentation in post-craniotomy scarring. Asian Journal of Surgery. Doi: 10.1016/j.asjsur.2025.09.142. https://doi.org/10.1016/j.asjsur.2025.09.142

[3] Liu Y, et al. (2025). Scalp micropigmentation for localized alopecia including scarring. Journal of Cosmetic Dermatology. Doi: 10.1111/jocd.70375. https://doi.org/10.1111/jocd.70375

[4] Popescu CE, et al. (2024). Stem cell therapy prior to FUE on scarred tissue. Journal of Medicine and Life. Doi: 10.25122/jml-2024-0303. https://doi.org/10.25122/jml-2024-0303