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

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 .