A fluid filled bump on your lip is either a mucocele or cold sore.
A mucocele is a mucous cyst which is harmless and painless and are fluid filled bumps that form when your salivary gland becomes blocked or even ruptured.
Cold sores are caused by the herpes simplex virus and are often painful and can even be itchy.
If the fluid filled bump on your lip is a mucocele cyst then it will eventually rupture on it's own within 3 to 6 weeks.
Do not try to remove the mucocele cyst on your own or try to rupture it yourself as it can make it worse and could cause infection.
If the mucocele cyst persists then a doctor dentist may use cryotherapy, laser treatment or even surgery to remove the cyst.
Bubbles of fluid on your lip also known as a mucous cyst or mucocele are harmless blisters which appear most often on the inner part of your lower lip.
The mucous cysts can also affect the inner cheeks, gums and tongue and the floor of the mouth.
Oral mucoceles also known as mucous cysts often occur due to minor trauma such as from biting your lip.
If it's bothering you then you may want to seek medical treatment but in most cases they go away within 3 to 6 weeks and are nothing to worry about.