Procedure: Plump up creased, furrowed, or sunken facial skin; add fullness to lips and backs of hands. Works best on thin, dry, light-colored skin. 
Length: 15 minutes to 1 hour per session. 
Anesthesia: Collagen: usually none; local may be included with the injection. Fat: local. 
In/Outpatient: Outpatient. 
Side Effects: Temporary stinging, throbbing, or burning sensation. Faint redness, swelling, excess fullness. 
Risks: Collagen: allergic reaction including rash, hives, swelling, or flu-like symptoms; possible triggering of connective-tissue or autoimmune diseases. (A skin test is required before collagen treatment to determine whether an allergy exists.) Both: Contour irregularities, infection. 
Duration of Results: Variable; a few months to 1 year.