Restylane is the trade name for a specific formulation of non-animal sourced hyaluronic acid. It is composed of cross-linked long chain hyaluronic acid, and is (USA) FDA approved for cosmetic injection into subdermal facial tissues.
Most commonly, it is injected under wrinkles and aging lines of the face such as the nasolabial folds, melomental folds, "crows feet" and forehead wrinkles. It may also be used for filling aging-related facial hollows and "orbital troughs" (under and around the eyes).
Restylane is most commonly used for lip augmentation.
It is produced by the Swedish company "Q-med", and has a long history of popularity in Europe and Australia, but has only recently been approved for use in the USA, due to the influence of Inamed's collagen ("Zyderm", "Zyplast") in that market.
The effects of Restylane last around 6 months or sometimes more. Variants produced by the same company give better duration, and so "Perlane" lasts 9+ months and "SubQ" lasts 15+ months. Recovery time from an injection takes around three days, as swelling and bruising can be a problem. Some practitioners will ask their patients to return to the practice two or three weeks after treatment for reassessment with view to a "top-up" if required.
In a recent study, when injected, Restylane seemed to regenerate collagen in skin.