Hyaluronic acid injections have been part of routine aesthetic practice for a long time. However, despite their widespread use and generally favorable safety profile, they may be associated with rare but clinically significant complications. One of these is secondary localized alopecia following HA filler injection.

In a 2025 study published in Clinical, Cosmetic and Investigational Dermatology, the authors presented a clinical case of this complication. They conducted a literature review covering 2000–2024 to assess its frequency, manifestations, and management strategies [1].

Clinical case: progression of the complication

The article describes a 23-year-old female patient who underwent facial augmentation with 5 mL of a hyaluronic acid filler injected into the left frontal region. The procedure itself was uneventful; however, four days later, localized erythema and pain developed at the injection site. After several days of persistent discomfort, the patient sought medical care and received three sessions of hyaluronidase with a total dose of 1500 units.

Pain subsided, but by day 15 post-injection, the patient noticed a patch of hair loss with superficial crusting, which continued to progress. Upon hospital admission, the lesion had well-defined borders. Dermoscopic findings included black dots, broken hairs, decreased hair density, scaling, and erythematous areas. Based on the temporal relationship with the procedure and clinical presentation, the authors considered this consistent with filler-induced alopecia areata [2].

Treatment approach

Initially, topical basic fibroblast growth factor (bFGF) gel was prescribed, but no significant spontaneous hair regrowth was observed.

Due to the lack of response, a multimodal approach was implemented, including Concentrated Growth Factor (CGF) injections, microneedling, and topical 5% minoxidil. CGF was obtained from autologous blood via differential centrifugation and injected into the lesion at 0.1–0.2 mL/cm² at a depth of 2 mm. Microneedling was performed using a 1.5 mm dermaroller, followed by minoxidil application to enhance transdermal delivery.

The patient underwent three sessions at 1–2 week intervals. According to the study, no adverse events occurred during treatment. At 4-month follow-up, complete hair regrowth was observed both clinically and dermoscopically.

Although encouraging, the authors emphasize that this is a single case and cannot define a standard of care, highlighting the need for further research.

Findings from the literature review

A key strength of the study is the systematic analysis of previously reported cases. The authors identified 13 full-text publications reporting 19 patients with alopecia following HA injections. Among them were 18 women and 1 man.

Hair loss most commonly develops within 1–4 weeks after the procedure. The temporal region was the most frequent injection site, and alopecia typically occurred adjacent to the injection area.

Diagnostic tools included trichoscopy, dermoscopy, ultrasound, and histopathology. Dermoscopic features reported in the literature included black dots, broken hairs, white or yellow dots, reduced follicular density, and vascular changes, supporting its value in early diagnosis and monitoring [2].

Possible mechanisms

The authors propose several mechanisms underlying this complication:

1. Extravascular compression due to high filler volume and its hygroscopic properties
2. Intravascular embolization by hyaluronic acid
3. Inflammatory tissue injury

In the presented case, the most likely explanation was pressure-induced alopecia, in which increased interstitial pressure reduces perfusion and leads to ischemia of hair follicles. In several reviewed reports, vascular compromise was also considered a key mechanism [4].

Importantly, early warning signs are not hair loss itself but rather symptoms such as pain, erythema, numbness, livedo-like vascular patterns (a net-like bluish-purple discoloration caused by microcirculatory impairment), and changes in skin color. The authors stress that early recognition significantly reduces the risk of irreversible tissue damage.

Role of hyaluronidase and other treatments

In the literature review, hyaluronidase was the primary emergency intervention, used in 16 out of 19 cases. Dosages varied widely, from 50 to 69,000 units, reflecting the lack of standardized protocols.

The authors emphasize that hyaluronidase should ideally be administered within the first 48 hours after injection, when ischemic damage is still reversible. However, even delayed use may alleviate pain and improve tissue perfusion. Ultrasound guidance is suggested to improve precision in targeting the filler [3, 5].

Additional treatments reported in the literature included minoxidil, intralesional triamcinolone, platelet-rich plasma (PRP), bFGF, hyperbaric oxygen therapy, and botulinum toxin A. Outcomes varied from complete regrowth to partial recovery or, in some cases, scarring alopecia.

Implications for clinical practice

The practical takeaway is clear: prevention is more important than treatment. The authors recommend evaluating scalp condition and obtaining a history of hair loss before the procedure, especially when injecting the forehead, temples, or scalp.

Practitioners should have a thorough understanding of vascular anatomy and high-risk zones, use slow, low-pressure injection techniques, apply minimal effective volumes, and avoid overcorrection. If additional product is required, staged treatments are safer than large single-volume injections.

Aspiration is discussed as a safety measure, though its reliability is limited. The use of blunt cannulas (25G or larger) is recommended, along with readiness to recognize vascular complications and initiate treatment [4] promptly.

At the same time, the limitations of current evidence must be acknowledged. The available data are based on a single clinical case and 13 publications reporting 19 patients, with heterogeneous diagnostic methods, treatment protocols, and follow-up durations. Therefore, these findings cannot be considered a standardized guideline but rather a clinical framework.

The authors conclude that alopecia after HA fillers is a rare but real complication. Early diagnosis and prompt intervention are critical to minimizing the risk of irreversible hair loss. For clinicians, this highlights the importance of not only technical proficiency but also vigilance for early signs such as pain, erythema, livedo-like vascular patterns, and other indicators of ischemia that may precede more severe vascular complications.

References

1. Jia L., Xiong J., Zhao C. et al. Alopecia secondary to hyaluronic acid injection: a case report and literature review. Clin Cosmet Investig Dermatol 2025; 18: 1565–1577. doi:10.2147/CCID.S524217
2. Asz-Sigall D., Inigo-Gomez K., Ortega-Springall M.F. et al. Alopecia secondary to hyaluronic acid embolization: trichoscopic findings. Skin Appendage Disord 2019; 5(6): 396–400.
3. Zheng C., Fu Q., Zhou G.W. et al. Efficacy of percutaneous superficial temporal arterial hyaluronidase injection for hyaluronic acid filler-induced necrosis of frontotemporal skin and/or the ipsilateral scalp with subsequent alopecia. Aesthet Surg J 2023; 43(2): NP77–NP83.
4. DeLorenzi C. Complications of injectable fillers, part 2: vascular complications. Aesthet Surg J 2014; 34(4):5 84–600.
5. Schelke L.W., Decates T.S., Velthuis P.J. Ultrasound to improve the safety of hyaluronic acid filler treatments. J Cosmet Dermatol 2018; 17(6): 1019–1024.