Adverse reactions to injectable soft tissue permanent fillers.

Background: Synthetic injectable facial fillers with a permanent effect are widely atoxic and nonimmunogenic, but they differ with respect to composition and in chemical and biologic characteristics. Yet, they all act as foreign bodies in the tissues eliciting a host response that try to remove the gel. Inflammatory nodules may develop at the sites of injection-for some fillers, many years later, for others, not.