Extract

To the Editor:

The scientific basis for the application of substances for soft tissue augmentation is critical. It is used to support the cosmetic application of an agent and define the adverse event profile. Unfortunately, the scientific literature concerning these agents is often confusing.

In particular, many articles have attributed reactions to hyaluronic acid (HA) fillers to hypersensitivity. Recently, Dr. Karyn Grossman discussed such cases.1 Nevertheless, on close inspection, the literature fails to identify allergy as the etiology.

Hyaluronic acid is a common thread, and identical, among all vertebrates.2 It is produced from enzymes in the cell membrane contained in what has been theorized to be a specific organelle. Commercial HA products have a molecular weight between 1 and 10 million. In the human body they have a very fast turnover, except in the eye. Their usefulness for aesthetic indications requires cross-linking or other modifications to increase residence time in tissues.

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