To dream that you have a blister indicates that some minor annoyance or problem is draining your energy and time. Consider how you may have gotten the blister. If you got the blister from manual and hard labor, then it indicates that you need to put forth more effort in order to overcome your little problems. To dream that you got the blister from a burn suggests an emotional or relational problem.
Where the blister is located is also significant. If the blister is on you hand, then it suggests that you are having issues related to power and competency. If the blister is on your face, then it indicates issues related to your identity, self-image, and self-identity.