If you have a blister, you should keep the blister intact as long as possible. Once it breaks, make sure to keep it moist with Vaseline or Aquaphor and don't remove the roof of the blister. You should also wear plenty of sunscreen and notify your doctor. If it is just swelling and not a blister, there is nothing to worry about. Just protect yourself from the sun and ice the area to help the swelling resolve a bit sooner.
These answers are for educational purposes and should not be relied upon as
a substitute for medical advice you may receive from your physician. If you
have a medical emergency, please call 911. These answers do not constitute
or initiate a patient/doctor relationship.