Overall, dermal fillers are considered safe but the possibility of side effects cannot be completely ruled out, as with any medical procedure. Most of the side effects associated with dermal fillers are short-term, occurring almost immediately after the injection and resolving in less than a few hours. Some prolonged side effects have, however, been reported, although on rare occasions.

The temporary side effects that may be experienced include:

1. Bruising and swelling
2. Bleeding from injection sites
3. Localized redness and tenderness.

More severe side effects that have been reported include:

1. Prolonged swelling (lasting for over one week)
2. Secondary infection of bruising site
3. Asymmetrical lips
4. Tissue loss arising from injection into a blood vessel
5. Allergic reactions which may lead to anaphylactic shock.

You should inform your doctor immediately if you notice any severe or persistent side effect.