They are safe, and the lip filling procedure is also safe, there is a low risk of complications or side effects. The best and most commonly recommended lip fillers are hyaluronic acid fillers, including Juvederm and Restylane. These fillers produce consistent and predictable results, have a very low risk of side effects, and have no downtime after treatment. Also, if you don't like the results, hyaluronic acid-based fillers are easy to reverse if needed.
Most of the side effects of lip injections are temporary, such as bruising and swelling. More serious side effects are usually associated with unprofessional handling, such as inadvertent injection of Juvederm into a blood vessel. Before a treatment with Juvederm, talk to a medical professional about your goals and aesthetic expectations.