The main study question was as follows: In patients with pilonidal sinus disease (all stages and severities), does laser hair removal as the major non-surgical therapy, post-surgical adjunct, or prophylaxis reduce disease recurrence in comparison with no hair removal, standard hair removal, or surgery only?

The research question was framed using the PICO framework, as detailed in Table 1 below.

Table 1. PICO framework for the systematic review.

Two authors searched the following electronic databases; PubMed/MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, and Google Scholar in January 2026. All the identified primary studies were screened based on the pre-defined eligibility criteria to identify eligible studies. Only studies with a full English text or an available English translation were retained for the final analysis. The detailed search terms and filters that were used on each database (combined using Boolean search string) were as follows.

PubMed/MEDLINE: ("pilonidal sinus"[MeSH] OR "pilonidal disease"[tiab] OR "pilonidal cyst"[tiab] OR "sacrococcygeal sinus"[tiab]) AND ("laser hair removal"[tiab] OR "laser epilation"[tiab] OR "laser depilation"[tiab] OR "laser hair depilation"[tiab]) AND ("treatment"[tiab] OR "recurrence"[tiab] OR "therapy"[tiab]) AND humans[MeSH] AND English[lang] AND ("2000/01/01"[Date - Publication]: "2024/12/31"[Date - Publication])

EMBASE: ('pilonidal sinus'/exp OR 'pilonidal disease':ti,ab OR 'pilonidal cyst':ti,ab OR 'sacrococcygeal sinus':ti,ab) AND ('laser hair removal'/exp OR 'laser epilation':ti,ab OR 'laser depilation':ti,ab OR 'laser hair depilation':ti,ab) AND ('treatment outcome'/exp OR 'recurrence':ti,ab OR 'therapy':ti,ab) AND [humans]/lim AND [english]/lim AND [2000-2024]/py

CochraneCENTRAL: ("pilonidal" AND ("laser hair" OR "laser epilation" OR "laser depilation" OR "laser hair depilation")) with Publication Year from 2000 to 2024

CINAHL: ("pilonidal sinus" OR "pilonidal disease" OR "pilonidal cyst") AND ("laser hair removal" OR "laser epilation" OR "laser depilation") Limiters: English Language or available translation; Published Date 20000101-20241231

GoogleScholar: ("laser hair removal" OR "laser epilation" OR "laser depilation") AND ("pilonidal sinus" OR "pilonidal disease") AND ("recurrence" OR "treatment") sorted by relevance, custom range 2000-2024, first 200 results screened

Studies were evaluated against pre-specified inclusion and exclusion criteria prior to the search, as detailed in Table 2.

Table 2. Inclusion and exclusion criteria.

All the identified records were loaded into Rayyan QCRI software to be de-duplicated and screened blindly. After the de-duplication, two authors screened titles and abstracts against the eligibility criteria. All potentially eligible studies were located and accessed using the full-text article and reviewed by the authors independently. Any disagreements were addressed via consensus building and discussion, where it seemed appropriate, by consulting a third senior reviewer. In a PRISMA 2020 flow diagram (Table 3) below, the study selection process is summarized.

Table 3. Study selection summary (PRISMA 2020 Flow).

Two reviewers independently used a pre-piloted standardized data extraction form to extract data (Table 4). The variables to be retrieved in each of the included studies were: the study author and year of publication; country of study; study design; sample size and patient demographics (age, sex, Fitzpatrick skin type where reported); laser type and technical parameter (wavelength, fluence, pulse duration, spot size, cooling); treatment regimen (number of sessions, intervals, adjunct surgical procedure); primary outcome (recurrence rate and definition); secondary outcomes (wound healing, quality of life, adverse events, patient satisfaction); and follow-up period. For comparative studies (RCTs and case-control) both intervention and control groups were extracted as two sets of data.

Table 4. Laser pilonidal systematic rv data extraction.

The validity of the included studies was evaluated by means of validated appraisal tools. In the case of RCT, Cochrane Collaboration Risk of Bias Tool (RoB 2.0) was used, and the information about five domains was evaluated: randomisation process, non-adherence to intended interventions, missing outcome data, outcome measurement, and selection of reported results. All domains were rated by the level of low risk, some concerns, and high risk of bias. In the non-randomised studies (cohort studies, case-control studies, retrospective series), the Newcastle-Ottawa Scale (NOS) was applied with maximum 9 stars in three areas including selection, comparability and outcome. The studies with a score of 7 stars and above were categorized as high quality; 4 - 6 stars as moderate quality and 3 stars and below as low quality. Table 5 summarises the results of quality assessment.

Since the included studies have a wide range of heterogeneity in terms of study design, patient population, laser parameters, and outcome reporting, formal meta-analysis of all the data was not conducted. Rather, a narrative synthesis was held, which involved categorizing studies according to their clinical setting (primary treatment or adjunct to surgery), type of laser, and outcome. Recurrence rates are in percentages and absolute event counts are found where necessary. In the case of RCTs odds ratios (OR) with 95 percent confidence intervals (CI) were noted.

346 records were found by this electronic database search (PubMed: 143; EMBASE: 98; CENTRAL: 32; CINAHL: 27; Google Scholar: 46). After the elimination of 89 duplicates, 257 records were filtered at the title and abstract level, 186 being excluded. The other 71 full-text articles were evaluated as to their eligibility; 18 (Laser ablation of sinus tracts only: 11; Case reports < 4 patients: 5; Non-English, no translation: 5; No follow-up data: 4; Duplicate cohort: 8; Systematic reviews/meta-analyses without extractable original data: 4; Citation-source mismatch identified on full-text re-verification, i.e. cited reference did not contain the reported LHR-PSD outcome data: 5). In the ultimate systematic review, eleven studies were incorporated the flow diagram is presented as Table 3.

The eleven included studies were carried out in different geographic locations, with most studies happening in the United Kingdom (n = 4) [15]-[18], Turkey [19], the United States of America [20], France [13], Egypt [12][21], Saudi Arabia [21], German [22]. The total number of the study population was 870. The range of age of the patients in the identified literature was between 11 - 35 years, which is believed to be the highest population in PSD. Majority of the studies were male dominated, with an average of 70 - 80 percent of all participants. Most of the studies (n = 5) considered LHR as an intervention used after the surgical excision of PSD [7][11][15][17][18]. Three included pre-surgery and post-surgery operations [13][15][23]. Three of them involved a primary non-surgical LHR arm [7][11][19], and three of them assessed LHR as an intervention in the presence of recurrent PSD after multiple previous surgical procedures [13][20][22]. The studies utilized a variety of laser; Diod 810 nm and Nd:YAG 810 [7][20][22][24], Alexandrite laser 755 nm [18], Nd:YAG laser nm 1064 [12], alexandrite laser and Nd:YAG [25], Alexandrite 755 [23] and 755 nm Alexandrite laser and Nd:YAG laser nm 1064 [22]. The number of sessions also differed significantly: most of the studies applying single sessions of 4 - 8 sessions separated by intervals of 4 - 8 weeks [7][13][16][18][21][22] and 2 - 3 weeks [24]. Table 5 (data extraction form) provides a summary of the key study characteristics.

The summary of quality assessment (Table 5) is provided as follows; Two out of the five RCTs were evaluated as moderate-to high-quality using the Cochrane RoB 2.0 tool [7][21][22], with the remaining three having some concerns mainly associated with the nature of the intervention as it was impossible to blind the participants and the clinicians on the treatment allocation [19][20]. Out of the non-randomised studies, four studies were graded as high quality (NOS 7 stars and above) [16]-[18][20] and 2 were moderate to low quality (NOS 4 - 6 stars) [13][22]. The main sources of risk of bias in some studies were the absence of a control group [13][15]-[17], self-selection bias (laser treatment usually necessitated self-referral or insurance approval) [18][20], and the definitions of recurrence of the variables, as well as relatively short follow-up [19][21]. No study was judged to have poor reporting on adverse events and laser parameters.

Table 5. Quality assessment of included studies.

3.4.1. LHR as Post-Operative Adjunct to Surgery

The strongest and the most regular evidence is about LHR as a post-operative supplement after the surgical removal of PSD [7][13][15][16]. In 6 studies that assessed this indication, recurrence rates in LHR treated groups have ranged between 0% and 13.3%, which is a significant and uniform decrease relative to the historical surgical recurrence rates of 11% - 50% in the control groups [7][18][21][22].

There is the strongest comparative evidence provided by two RCTs. Ghnnam and Hafiz [21] randomised 86 postoperative patients using Alexandrite LHR (n = 45) and razor shaving (n = 41); at 24 months, the recurrence rate in the LHR group was 2.3% compared to 17.1% in the razor group (p < 0.05) [21]. The procedure was also comfortable with no complications. Badawy and Kanawati [12] randomised 45 patients to post-operative Nd:YAG LHR and no hair removal, with recurrence rates of 4.4% and 28.9% respectively (p < 0.05) [22]. With follow up periods lasting between 12 to 23 months, it is seen that when using Nd:YAG LHR had none of the patients requiring further surgical treatment to date. In this type, pain was the most frequent side effect in 6/14 patients (40%). Nd:YAG LHR is strongly advocated for in in non-complicated recurrent PNS, LHR is strongly advocated to be started before and continued after doing surgical treatment.

Kelati et al. [13], in a retrospective case-control study, found a recurrence rate of 8.3% in the post-operative LHR group compared to 51.7% in the control group (surgery alone) (p < 0.001), a roughly 6-fold reduction [13]. In this study, 2 patients had abnormal healing or persistent sinus after surgery alone compared to none in laser procedure after surgery group. Comparatively, the systematic review by Pronk et al. [9] of 14 studies (963 patients) indicated a recurrence rate of 9.3% in post-operative LHR and 23.4% in conventional hair removal [9].

In a real-world retrospective cohort study of 97 LHR patients treated over six years, Andrew et al. [15] found only one recurrence (1.0%), and the number of LHR sessions was the only independent predictor of treatment success (p < 0.001), independent of the type of surgery, disease severity, or type of laser [15]. On the other hand, recurrence rate was 12% for 64 patients who underwent 6 or more sessions of laser depilation after elective surgery [18]. Similarly, six of fifteen (40%) who completed laser treatments had resolution without surgical intervention [16]. In this study, of the nine patients who underwent surgery, six (67%) resolved after one surgery [16]. Therefore, laser hair removal is associated with improved quality of life.

The results of recurrence rates in all comparative studies are summarised in Table 6.

Table 6. Comparison of recurrence rates across key included studies.

3.4.2. LHR as Primary Non-Surgical Treatment

The evidence for LHR as a non-surgical intervention, not combined with surgery, is still underdeveloped yet promising. The first prospective pilot study specifically aimed to study LHR as a primary therapy in patients aged 13 - 35 with moderate to severe PSD who wished to avoid surgical excision [16][24]. This is not fully supported in research [26][27]. Laser epilation is seen as an adjunct to standard care in preventing recurrence of pilonidal disease in adolescents and young adults compared to standard care alone [7][15][18][21][22][24] and children (13 years and above) [16]. The primary outcome was the rate of re-occurrence after one year, while the secondary outcomes included health-related quality of life, disability days, health care satisfaction, disease-related attitudes and perceived stigma, and rates of procedures, surgical excisions, and postoperative complications [7]. It was found that the rate of patients who experienced a recurrence within a year was significantly lower in the LE treatment group than in the standard care group (−23.2%; 95% CI, −33.2 to −13.1; p < 0.001). From the included studies, it is clear laser epilepsy reduced recurrence of pilonidal disease after 6 months or 1 year and it is safe and well tolerated in patients with pilonidal disease [7][13][15][16][21]. This finding corresponds with research on efficacy of laser technology as a non-surgical treatment in resolving pilonidal disease [24]-[26].

Also, of 15 patients who finished the entire LHR regimen (3 - 8 sessions, Alexandrite 755 nm, endpoint: no terminal hair), 6 (40%) had complete disease elimination without any surgical intervention at 18 months follow-up [16]. out of fifteen, nine patients ultimately required surgery, of whom six (67%) achieved resolution with a single surgical procedure [16]. Quality-of-life (DLQI) scores increased considerably after LHR (mean change DLQI: −4.6; Children’s DLQI: −6.0) without any adverse events. Case series have also described patients treated successfully with Alexandrite LHR alone, without any surgical intervention and with no recurrence at follow-up, while other retrospective series have described patients managed with conservative measures combining LHR and hygiene optimisation [15]. On the other hand, when using Nd:YAG LHR, after surgical excision of PNS (Patients group), it is noted that 7 patients out of 10 in the control group developed recurrent PNS and that pain was the most frequent side effect [22].

Andrew et al. [15] also reported a sub-analysis of 32 patients (33% of all patients) who were treated with LHR with no surgical repair: 25 of them (78%) showed improvement or healing of their PSD [15]. These results are consistent with the theoretical premise of LHR, which holds that removing the causal hair stimulus may permit resolution of inflammation and healing of early-stage sinuses and pits without formal excision [27]. The three of the included studies [16][17][22] can be seen to have used small samples (n = 15 - 22) and a post hoc subgroup analysis within a larger retrospective cohort, rather than from a study specifically designed and powered to evaluate LHR as a primary treatment. These results should therefore be regarded as preliminary and hypothesis-generating rather than as definitive evidence supporting first-line use of LHR.

3.5.1. Wound Healing

Some studies have compared the effect of LHR on post-operative wound healing. Lopez et al. asserted that 100% (19 participants) in their pediatric cohort achieved healing without wound breakdown or wound infection following LHR [24]. Comparatively, a systematic review by Grabowski et al. similarly noted that the benefit of LHR did not appear to depend on the type of surgical procedure performed [4]. In our study, however, Demircan et al. (2018) had one group of patients exposed to the Karydakis flap reconstruction technique only and another exposed to two sessions of laser epilation 2 weeks before and 3 weeks after the surgery and found no statistically significant differences between the groups in terms of surgical site infection, wound separation, abscess formation at the anytime postoperatively [19]. This could be down to treatment duration.

3.5.2. Quality of Life

Formal measurement of quality-of-life outcomes was reported in only a small proportion of studies. LHR was associated with a significant improvement in DLQI scores [16], and Khan et al. [17] reported a significant improvement in physical activity and return to normal daily functioning after LHR in all 19 patients with recurrent PSD; all 19 patients described the treatment as non-invasive and convenient to administer, with no exacerbations reported post-LHR [17]. Also, laser epilation was found to be effective when it comes to prevention of recurrence, but no significant differences in treatment effects based on sex, body mass index, previous disease, prior surgical excision, or annual household income (all p > 0.05) [20], but subtle differences effectiveness of laser epilation to reduce pilonidal disease recurrence rates may vary based on race and ethnicity [19][20].

3.5.3. Adverse Events and Safety Profile

LHR was also reported as consistently and uniformly safe in all 11 included studies, with an excellent adverse event profile. Mild to moderate pain or discomfort during treatment was the most commonly reported adverse event, especially in the perianal region, where cutaneous sensitivity is heightened. This was generally managed with topical anaesthetic cream 30 - 60 minutes before laser sessions, making the procedure tolerable for the great majority of patients. A small number of studies observed transient post-treatment erythema that subsided on its own within hours [19][20].

There were no reports of permanent hyperpigmentation, hypopigmentation, scarring, infection attributable to laser treatment, or other significant adverse events in any of the 28 included studies. Andrew et al. [15] directly noted that there were no complications among 97 consecutive patients over the six-year study period [20]. According to Janek et al., no adverse events were noted in their prospective pilot trial using the Alexandrite laser (755 nm) among the 15 patients who completed treatment [15]. More broadly, the longer wavelength and reduced melanin absorption of the Nd:YAG laser (1064 nm) are thought to make it comparatively safer than the shorter-wavelength Alexandrite laser in patients with darker skin phototypes (Fitzpatrick IV - VI), who may be at greater risk of epidermal injury with Alexandrite owing to its higher melanin absorption.

Adverse event data from the included studies are summarised in Table 7.

Table 7. Adverse events and safety profile across included studies.

3.5.4. Number of Sessions and Treatment Parameters

The number of LHR sessions was found to be a key determinant of successful treatment in several studies. On multivariate analysis, Andrew et al. [15] found that it was the only independent predictor of PSD improvement (p < 0.001) [15]. The median number of sessions reported across studies was 4 to 8, with a 4 - 8 week interval to permit follicular cycling. Various authors have argued that a treatment endpoint of 70% or more reduction in visible hair—or, preferably, complete clearance of terminal hair in the natal cleft—should be the treatment goal [27]-[29].

Laser parameters differed significantly across the included studies. The standard settings used for the Alexandrite laser were a wavelength of 755 nm, fluence between 14 and 26 J/cm², pulse widths between 3 and 10 ms, and spot size of 15 - 18 mm with active skin cooling. Nd:YAG was set at a wavelength of 1064 nm, fluences of 30 - 60 J/cm² and pulse durations of 10 - 30 ms. Such heterogeneity of treatment protocols complicates direct comparison of the efficacy of modalities.

This systematic review summarises the evidence of 11 studies involving more than 870 patients and presents a thorough evaluation of LHR as a non-surgical intervention method in PSD. The general conclusion is clear: LHR as a post-operative adjunct is significantly and consistently more effective at reducing the rate of PSD recurrence than traditional hair removal or no hair removal, and it has a favourable safety profile. This conclusion is supported by pooled estimates from a previously published meta-analysis of three RCTs (OR 0.319; p = 0.0001) [8]. LHR also shows encouraging, but still preliminary, results as a sole non-surgical therapy, with some patients achieving disease resolution without surgery.

LHR is supported by a strong theoretical foundation based on the aetiological primacy of hair in the pathogenesis of PSD. Hair, especially the coarse terminal hair of the natal cleft, penetrates the skin under the mechanical forces of sitting and movement, acting as an antigenic foreign body that perpetuates an inflammatory cycle resulting in the formation and recurrence of sinus tracts [6][7]. Traditional temporary methods of hair removal (shaving, depilatory creams) are insufficient because the effect is temporary: hair regrows quickly, and the newly sharpened ends of shaved hair may actually contribute to re-penetration, an idea supported by the observation that razor hair removal was associated with a higher risk of recurrence [10].

Permanent hair reduction with laser addresses the root cause of the pathological stimulus rather than the symptoms, because destruction of the follicular stem cells in the bulge region progressively converts coarse terminal hairs into fine vellus hairs unable to penetrate the skin [29]. In the context of primary treatment, LHR removes the ongoing provocative stimulus, which may permit early-stage sinus tracts and pits to resolve without surgery—a hypothesis consistent with the 40% rate of non-surgical healing reported in the single pilot study by Janek et al. [16], though this remains to be confirmed in larger studies.

No single laser modality has been shown to be superior for treating PSD; nevertheless, several factors are considered when choosing a modality. The Alexandrite (755 nm) laser is highly effective for hair removal in lighter skin types (Fitzpatrick I - III), owing to its high melanin absorption. The Nd:YAG laser (1064 nm) is favoured in darker skin types (Fitzpatrick IV - VI) because its longer wavelength is less absorbed by melanin and penetrates more deeply, which is associated with a lower risk of epidermal injury in these skin types.

The study by Andrew et al. [15] did not reveal any statistically significant difference in treatment outcomes based on the type of laser used (p > 0.05), suggesting that efficacy in PSD may be more closely associated with the completeness of hair removal achieved than with the specific modality used. This has practical implications for service delivery, as it may allow treatment to be tailored to locally available laser systems without compromising outcomes.

LHR as a non-surgical option for PSD represents a potential paradigm shift for certain patient populations, although the supporting evidence remains preliminary. Young patients, young adults, and teenagers who wish to avoid surgical morbidity, a long healing process, absence from school or work, and the risk of postoperative wound complications could be candidates for a primary LHR-first approach if this indication is confirmed in future trials. Preliminary data from a single pilot study Janek et al. [16] and a subgroup analysis within a larger retrospective cohort Andrew et al. [15] suggest that some patients, particularly those with less advanced disease, may achieve resolution using LHR alone; given the small samples and exploratory nature of these analyses, however, this should be regarded as hypothesis-generating rather than established practice [15][16].

Recent guidelines from the American Society of Colon and Rectal Surgeons (ASCRS) and the American Pediatric Surgical Association (APSA) recognise conservative management, including hair removal, as a first-line approach to mild disease, but have not yet fully incorporated LHR into clinical pathways [5]. As primary-LHR evidence matures, future guideline updates may be able to formalise its role.

A common finding across the body of research is that a greater number of LHR sessions correlates with better outcomes, a relationship that multivariate analysis identified as independent [15]. The lowest recurrence rates were generally reported in studies using 6 - 10 sessions, while the highest recurrence rates were seen in studies using fewer sessions (2 - 4). The conventional treatment target of 70% hair reduction may not be the optimal endpoint; complete hair removal may represent better practice [7]. This has implications for insurance coverage, service planning, and patient counselling regarding realistic treatment timelines.

One clinical use of LHR is in treating recurrent PSD in patients who have undergone multiple previous operations. Repeated operations are associated with increasing morbidity, including extensive scarring, distorted anatomy, impaired wound healing, and reduced tissue vitality. Khan et al. [17] demonstrated that LHR in this difficult subgroup achieved a 0% new recurrence rate at 36 months, with a significant improvement in quality of life [20]. LHR may therefore serve as a definitive non-surgical therapy in such patients, interrupting cycles of recurrence and re-operation.

Although the evidence base is increasing and promising, several significant limitations remain. First, most included studies are non-comparative and retrospective, and are prone to selection bias and confounding. The highest level of evidence—RCTs—is limited to five studies, most of which could not blind participants or clinicians to treatment allocation given the nature of the intervention.

Second, the study populations, PSD staging and severity measures, laser type and parameters, treatment regimens, recurrence definitions, and follow-up length are all significantly heterogeneous. This heterogeneity makes formal meta-analysis of the full dataset, and cross-study comparison, challenging. Third, most studies have relatively short follow-up (12 - 36 months); since PSD recurrence may occur years after therapy, longer follow-up is needed to establish long-term effectiveness. Fourth, the lack of data on quality of life, cost-effectiveness, and patient-reported outcomes represents a substantial gap. Fifth, LHR services are unevenly distributed geographically, and reimbursement is inconsistent, as LHR is often categorised as a cosmetic procedure by healthcare payers, which hinders broader adoption.

Other non-surgical methods for PSD have also been described, including crystallised phenol application, fibrin glue injection, platelet-rich plasma, and endoscopic sinus tract treatment [30], although these are mostly minimally invasive measures focused on the sinus tract itself rather than the underlying hair stimulus. Among hair-targeting non-surgical strategies, LHR is the only method with a strong evidence base capable of producing long-lasting follicular destruction and an associated reduction in recurrence. Traditional depilatory procedures are insufficient, as their effect is short-term, and shaving may even increase disease risk [10]. LHR thus occupies a distinct, and largely unmatched, position among non-surgical PSD treatments by addressing the underlying pathophysiological process. Beyond the clinical evidence reviewed above, broader reviews of overall PSD management have also highlighted the increasing integration of LHR into multidisciplinary care pathways [31][32], including quality-improvement initiatives that track LHR-related clinic visit burden in dedicated pilonidal clinics [26].