Adverse Events Associated with Hyaluronic Acid Filler Injection for Non-surgical Facial Aesthetics: A Systematic Review of High Level of Evidence Studies.

BACKGROUND: Hyaluronic acid (HA) dermal fillers are widely used in aesthetic medicine. While generally safe, potential complications can arise. OBJECTIVE: This systematic review aims to identify and classify potential complications linked to the use of HA dermal fillers, as informed by high-quality, low-risk-of-bias studies. METHODS: This review follows the Cochrane review standards for clinical systematic reviews. This systematic review analyzed 48 high level of evidence studies on the use of hyaluronic acid (HA) dermal fillers in non-surgical facial aesthetics and the adverse events that occurred.The inclusion criteria were randomized control studies on HA dermal fillers and their complications. Excluded were case reports, case series, observational studies, and other non-randomized research due to their inability to provide generalized conclusions and their inherent publication bias. RESULTS: Adverse events were classified into three categories: expected reactions, product or technique-related adverse events, and severe adverse events. Most adverse events were short-lived injection site reactions, which resolved spontaneously. Specific HA fillers and injection techniques influenced the occurrence of adverse events, which generally resolved within weeks without treatment. Severe adverse events were rare, persisting for months and requiring active medical intervention. DISCUSSION: This classification system can enhance understanding, prevention, and treatment of HA filler complications, and support patient education. The common complications were injection site reactions, with persistent symptoms treated with topical steroids, NSAIDs, or hyaluronidase. Severe complications included severe edema, angioedema and others, often necessitating specific treatments. CONCLUSION: HA dermal fillers are generally safe and effective, with most adverse events being transient and mild to moderate in severity. Severe adverse events, although rare, do occur and are generally non-treatment related. Informed consent, patient education, and professional training are crucial for safe and successful outcomes. Level of Evidence II This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .