Injectable Fillers for Atrophic Acne Scars: A Systematic Review of Mechanisms, Evidence, and Clinical Algorithms

Background: Acne affects 9.4% of the global population, with the highest prevalence among adolescent males (12– 25 years of age). More than 95% of patients develop persistent scarring, predominantly atrophic acne scars (AAS). These scars markedly impair facial aesthetics, psychological well-being, and quality of life, and increase the risk of depression and suicidal ideation. Conventional therapies (eg, Dermabrasion, Subcision and Traditional Ablative Lasers) show limited efficacy for shallow AAS and are associated with procedural pain, delayed onset of improvement, and a need for repeated sessions. Dermal fillers provide a promising alternative by delivering immediate volumetric correction and aesthetic enhancement while also stimulating long-term collagen production with minimal invasiveness and favorable safety profiles. They therefore represent a novel therapeutic approach for AAS. Aim: This review systematically evaluates the clinical utility of dermal fillers for treating AAS and explores future diagnostic and therapeutic approaches. Methods: We searched the PubMed and Web of Science databases for studies published in the past 10 years, categorizing and evaluating the efficacy and adverse effects of different dermal fillers for treating AAS. Results: Twenty-four studies met inclusion criteria, involving collagen-based fillers, hyaluronic acid fillers, collagen stimulator fillers, autologous fat, and decellularized matrix fillers. All filler types demonstrated significant scar improvement. Effects ranged from 3– 6 months to > 24 months. CaHA, PCL, and autologous fat/SVF demonstrated ≥ 6-month durability. Transient erythema, edema, and ecchymosis were common. Infrequent events included nodules and hyperpigmentation. No severe complications were reported. Conclusion: Multiple studies indicate that dermal fillers offer advantages over conventional therapies for atrophic scars. They provide immediate volumetric correction and stimulate long-term collagen production, with less tissue trauma than traditional approaches. Specific formulations also enhance skin hydration and may slow aging processes. Collectively, these benefits demonstrate substantial clinical promise, particularly when incorporated into combination therapies. Keywords: acne scars, fillers, HA, CaHA, PMMA