You will have swollen lips afterwards. This will mainly settle over the next 12 hours. Depending on the type of lip enhancement you have chosen, returning to work the following day should be OK.
Aftercare involves using a cold compress for the first day or so to help with any bruising or swelling that may occur.
Side effects with fillers are not that common however they can occur with bruising lasting 1-2 weeks or an allergic reaction which means the area can be red for up to a week. Occasionally a small lump can remain which if it does not settle with massaging can be dissolved with hyalase injections.