collagenDescription: Collagen is a natural structural component of our skin and connective tissues. Bovine, porcine and human collagen have all been used. Evolence is the latest porcine collagen dermal filler and is highly purified, but has recently been discontinued. Other fillers are more popular currently.

How it's done: Before undergoing collagen injections, patients often require a skin test to ensure there is no allergic reaction. Collagen is injected into the dermis to fill and plump. It is useful to restore fullness to lips, correcting facial folds and wrinkles and reshaping facial contours.

Recovery: Results are immediate, allowing a few days for the product to settle, and last four to six months on average. Minor complications can include irritation, swelling, itching, bruising or tenderness at the injection site. Nodules and bumps have been reported and can be treated with massage or short-term steroids.

Cost: $600 and up.