Dermal fillers are generally well-tolerated by most people, although there is a chance of temporary headaches and of bruising at the injection site. Rarely, there is a possibility of a droopy eyelid or asymmetry, both of which are temporary and reversible. The most common side effects of dermal fillers are mild tenderness after the injection, swelling (lips) and tiny bruises at the injection site. More rare side effects include the possibility of an allergic reaction, lumps or bumps or vascular occlusion (clogged vessel). While these side effects are extremely rare, Dr. Lewin is not only an experienced injector but also a medical doctor who can attend to these events quickly and effectively.