Delayed hypersensitivity reaction to hyaluronic acid dermal filler following influenza-like illness.

Background: Delayed reactions after facial hyaluronic acid injection are relatively rare complications. Their cause may be infectious or immune-mediated in origin, and their outbreak can be triggered, for example, by an influenza-like illness. Objective: To describe potential adverse event of influenza like illness following dermal filler injection. Methods: We report fourteen unusual cases of delayed hypersensitivity reaction to several brands of hyaluronic acid dermal filler following influenza like illness. Results: Increasing evidence implicates influenza infection in the pathogenesis of late onset filler reaction. Conclusion: Although there is a low risk of late onset adverse reaction with hyaluronic acid fillers, injecting physicians must be aware of the possible filler reaction following the influenza infection.