What is this bubble/blister I always get after lip filler? (Photo)

This can be a nodule. If this has happen to you before it could be that that is the way that part of your lip tissue (that exact spot) receives the filler. This can last 2-4 weeks and sometimes resolve on their own as the lip filler integrates itself into the tissue. If you notice the bump to get firm, red, hot, inflammed that may mean that its infected and you may need antibiotics. If your going to go for a touch up you should make sure to inform the provider who is treating you that you have history of this happening so they can watch you closely. I hope this helps!

I encourage you to follow up with your injector for an evaluation. It could be related to superficial filler. If that is the case it can be dissolved with hyaluronidase. It could also be a medical issue that is exacerbated by the filler treatment.

This looks like an area where filler was injected superficially and is visible under the skin. Dissolving the filler would remedy the problem. It may seem bigger after injections because of the associated swelling accompanying injections and lip filler's hydrophilic properties.

I think you should follow up with your provider or get seen by a plastic surgeon or auto otorhinolaryngologist when this happens. It looks to me like you’re developing a mucus cyst a.k.a. mucocele.
Mucus cysts form, typically from minor tissue damage and trapping mucus producing glands under the skin surface of mucous membranes
Best,
Mats Hagstrom, MD