How to get rid of a blister from writing too much?

Protect it: An unpopped blister represents a closed sterile environment. Yes on occasion one can become infected then it is time to open it, however the risk of infection in a well treated open wound is still greater than that of an intact blister. The blister will gradually resolve with time. If you still have a lot to write use a larger diam. Pen preferably with padding.

Prevent: Continued re-injury and allow time to heal.