Do a cold sore pusses?

It can appear so..: Small cold sores often appear with just slightly yellowish fluid (plasma-like) but larger ones can look like puss-filled lesion. The body white blood cells attack the virus, cause inflammation, fluid accumulation and thus appears as puss. These often resolves spontaneously. If it becomes larger and large with more redness/pain, it could secondary infection/boil. Consult doc. Good luck.

No: Cold sore usually form blister which gradually heals forming scab which disappears over few weeks. Pus formation would indicate superimposed bacterial infection.