It is a completely synthetic compound comprised of microspheres of calcium hydroxylapatite in an aqueous gel. Calcium is a natural substance already in the body, so Radiesse™ causes no allergic reactions making no allergy testing necessary. Radiesse™ is especially helpful in deeper creases and wrinkles such as the nasolabial folds and corners of the mouth. Radiesse™ may last a year or more. The most common side effect, as with any injection, is temporary redness and swelling at the injection site and typically resolves within two to three days.