Thank you for your question.There is no contra-indication to having lip fillers even if you have a history of cold sores. You will need to take antiviral medications (Valtrex / Acyclovir) before and after each time you are injected. If you have an active cold sore - you should not be injected. This prescription can be called in to your pharmacy so you can get and take the medication before you have your injection done.Current Hyaluronic Acid injection products result in beautiful, soft, enhanced lips when done by an experienced injector. The latest Allergan products - Volbella and Volift - last greater than 1 year and the outcomes are amazing. Seek out a well qualified PS in your area to discuss goals. Lip injections are an art form and you want an injector that understands the anatomy of a beautiful lip.All the best.Scott Barr, MD, FRCSC