Injections are most frequently used for cosmetic procedures to help rejuvenate skin and reduce the appearance of wrinkles. They are also used for lip augmentation. In an office procedure, a filler is inserted into the treated area using a fine needle. In the case of fat injections, a needle is used first to remove fat from a donor site. The fat is then treated before it is inserted into the desired site, such as the lips. Generally, injection procedures do not require any anesthetic. Although the filler may cause side effects (such as an allergic reaction), the injections themselves do not.