Doctors diagnose shingles based on a history of pain on one side with an accompanying rash and blisters, notes Mayo Clinic. They may run tests on the blisters to confirm a shingles diagnosis.
People suffering from shingles have symptoms such as pain, numbness or tingling, a red rash and itching, according to Mayo Clinic. Some people with shingles also experience headaches, fever, sensitivity to light and fatigue. The shingles rash normally appears in a small area on one side of the body, though it can also appear on the face or neck. People who suspect they have shingles should see their doctors, particularly if the rash appears next to the eye, as left untreated it can lead to permanent eye damage. People with compromised immune systems and people over the age of 70 should also see their doctors immediately if they have the symptoms of shingles.
People who have had chickenpox are at risk of developing shingles, as it is caused by the same virus, which may stay in the blood stream for years before symptoms of shingles develop, states Mayo Clinic. The exact reason why the virus becomes active and results in shingles is not known, as of 2015, though it may be connected to an inability to fight infections as people age. Shingles is contagious and can be passed to anyone who is not immune to chickenpox.