1. When the virus reactivates, it can cause a painful rash that develops into a cluster of small bumps.
   
   
2. The bumps turn into blisters that fill with fluid.
   
   
3. The blisters break open.
   
   
4. The sores crust over and finally disappear in two to four weeks.
   
   
5. Damage to the nerves causes pain that can last for months.

Graphic Courtesy of the US FDA.