The present invention relates to improved methods for filling the skin for cosmetic or medical purposes. Compositions comprising carboxymethyl cellulose (CMC), polyethylene oxide (PEO) and calcium ions can be made and have physical properties that depend on the amounts and types of CMC, PEO, and calcium ions to form ioniclaly cross-linked gels. Compositions can be formed into microspheres, coascervates, gels, or membranes. Gels, microspheres and coascervates can be injected directly into a site for dermal filling. Membranes can be surgically introduced, where they swell to form hydrated gels. After introduction, the dermal filler persists for a period of time and then can disintegrate and be removed from the body.