My shingles are on the arm. only 2 major sights, now the blisters are breaking but the area around them is a very large red hot circle...on antivir?

Cellulitis?: It is ok to have redness around the blisters but there should not be a'hot' feeling. You may have developed a bacterial superinfection of the shingles. You should call you doctor and certainly see him or her if the redness is increasing or you have an elevated temperature.

Have this checked.: Red, hot, swollen, with possible purulent drainage could mean a secondary bacterial infection has set in. Please have your doctor take a look at this.