The Posthyaluronidase Syndrome: Dosing Strategies for Hyaluronidase in the Dissolving of Facial Filler and Independent Predictors of Poor Outcomes.

Background: Hyaluronic acid dermal fillers are used extensively in periocular aesthetic medicine, and the incidence of filler-related complications is increasing. This study aimed to investigate the optimal dosing strategy for hyaluronidase and to identify predictors of poor outcomes. Methods: We performed a retrospective review of 157 orbits of 90 patients treated with hyaluronidase over a 4-year period. Demographic data, indication, and details of hyaluronidase treatment and outcomes were recorded. Results: The primary indication for dissolving filler was swelling in 52%, lumpiness in 20%, and before surgical blepharoplasty in 17%. The most frequently used hyaluronidase concentration was 150 U per mL in 66%, followed by 75 U per mL in 31%, 37.5 U per mL in 3%, and 100 U per mL in 1%. Outcomes were characterized as follows: 59% with a satisfactory result; 24% as insufficient treatment requiring further hyaluronidase; and 18% complaining of facial changes such as hollowing, indicating a post hyaluronidase syndrome. There was no statistical difference in outcomes between the 75 and 150 U per mL dosage groups ( Conclusions: The posthyaluronidase syndrome may be related to previous filler volume and duration, rather than the concentration or dose of hyaluronidase used. All patients should be informed about the risks of adverse effects after hyaluronidase treatment; patients with longer histories of filler use and higher total volumes should be advised of the increased risk.