Fillers are gels that are comprised of concentrated hyaluronic acid combined with lidocaine (local anaesthetic). As we get older, the soft tissues and fat pads in your face lose volume and start to sag, causing a “tired” or a “sad” look. 
Dermal fillers can replace the volume, enhancing natural glow and giving a refreshed look. The filler is injected into or under the skin to help improve the appearance of lines and wrinkles by plumping up the tissues, adding volume to areas where there has been loss due to the ageing process. The effect can been seen immediately and will improve further over the next 14 days. The effect lasts 12-18 months (often longer) as the body gradually removes the filler from the treated areas.
Fillers are formulated to different consistencies depending on the area being treated, eg lips need to move and stretch to allow speech and puckering so are treated with a softer more stretchy filler than cheeks which need more structure so a firmer filler is used.
Big lips are out, natural looking lips are in. I do not advocate the injection of large volumes of lip filler, my patients are happy to leave my clinic with natural looking and age appropriate aesthetic appearances. 
Filler dissolving is available, however, some fillers used by other clinics may not dissolve easily, please ask in clinic.