Unlike traditional filler, you do have to wait until the body breaks down lip threads, which means they aren't instantly reversible; plus, Dr. Chantrey says they can take a little longer to break down than hyaluronic acid-based filler. "This can be seen as a positive by someone who wants a longer-lasting result," she explains. "However, if you have a side effect such as an infection or a distortion, or you just don’t like the result, you can’t easily get them out." For this reason, Dr. Chantrey, like many qualified aestheticians in the UK, only uses fully reversible dermal fillers that have undergone strict and comprehensive clinical trials.