I almost exclusively use injectable hyaluronic acid (HA) fillers in the face.  There are several products available which work well.  This is composed of a naturally occurring substance found in the skin and is not made from animal products.  Although mentioned as a potential risk, I have never seen an allergic reaction to this product after injection.  There are studies which suggest that this type of filler stimulates collagen formation which is desirable in long-term reduction of wrinkles.  This is an absorbable filler that lasts approximately 10 months.  I know of no long term deleterious effects after injection of HA fillers.