Shingles is an infection of a nerve and the area of skin around it. It is caused by the herpes varicella-zoster virus, which also causes chickenpox.
Most people have chickenpox as a child, but after the illness has gone, the virus remains dormant (inactive) in the nervous system. The immune system keeps the virus in check, but later in life it can be reactivated and cause shingles.
How common is shingles?
About one in five people get shingles at some point in their life. Although it can occur at any age, it is most common in people who are over 50 years of age.
Shingles usually affects a specific area on either the left or right side of your body. The main symptoms are pain and a rash.
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.