Fillers are injectable treatments that add volume to sunken areas such as the cheeks and forehead to create a smooth, plump appearance. According to the Cleveland Clinic, they physically fill in the changes that occur as we age—such as a decrease in collagen, which causes the skin to thin and lose elasticity—to restore a more youthful look. The duration of results varies depending on the ingredient: hyaluronic acid (HA) lasts approximately 6 to 12 months; calcium hydroxyapatite (CaHA) lasts about one year; and poly-L-lactic acid (PLLA), which stimulates collagen production, is reported to last two years or more. However, the duration of results and outcomes vary significantly from person to person. Possible side effects include bruising, swelling, infection, asymmetry, and numbness; although rare, serious risks such as vascular-related vision problems have also been reported. During your consultation, it is advisable to confirm the ingredients used, whether they are approved, the injection site and volume, the duration of results, whether the ingredients are reversible, and the plan for managing side effects. This information is for informational purposes only and does not constitute a diagnosis. Please consult a specialist regarding the actual procedure.
[Source] https://my.clevelandclinic.org/health/treatments/22667-dermal-fillers