Lip fillers are a type of dermal filler that add volume to the lips. They are made of various materials, including synthetic hyaluronic acid (HA), which is a natural substance found in the body. Other materials used in lip fillers include collagen, poly-l-lactic acid, calcium hydroxylapatite, autologous fat injections, and polymethylmethacrylate. However, the most common fillers contain substances similar to hyaluronic acid. During a lip filler procedure, a healthcare provider will apply a topical anesthetic to the lips to numb them, and then use a thin needle to inject the filler. The effects of lip fillers typically last around 6 months, after which more injections are needed to maintain the volume of the lips. Lip fillers are a personal decision, and individuals who wish to get them should be in good physical health, have realistic expectations, and not have an active oral infection.