After the chickenpox virus has been contracted, it travels from the skin along the nerve paths to the roots of the nerves where it becomes inactive. The chickenpox virus then 'hibernates'. When the virus is reactivated, it travels via the nerve paths to the skin. It is not known what factors trigger a reactivation of the virus. Shingles generally affects the elderly, but occasionally occurs in children who have had chickenpox within the first year of their lives and in people with an immune deficiency.

Shingles can be a sign of immunodeficiency, caused by HIV or chemotherapy, stress, long time after sickness for example, but most people who get shingles have a normal immune system.

The first sign that a reactivation of the chickenpox virus is taking place is a burning sensation on the nerve paths along which the virus is travelling. Nerve paths typically form half-circles around the body. The pain and subsequent rash correspond to the position of the nerve paths and are almost always on one side of the body or face or limbs only, but more common in the trunk body.

The rash is typically accompanied by a fever and enlarged lymph nodes.

Two to three days after the pain has begun, a typical rash appears: small blisters on red, swollen skin. It resembles the type that is seen during an attack of chickenpox but covers a smaller area.

The rash usually reaches its peak after three to five days. Then, the blisters burst and turn into sores, which gradually scab over. The scabs fall off after two to three weeks.

Sometimes the area where the rash was located becomes extremely painful after the scabs have gone and can last from a few weeks to several months. This highly unpleasant after-effect of shingles is called postherpetic neuralgia.

The patient's medical history in combination with the appearance of the rash will usually be sufficient for making a diagnosis. If necessary, a scrape from the blisters can help identify the virus. A blood sample can also be used to confirm the initial diagnosis.
What happens if it gets worse?
The rash can become infected by bacteria.
An attack of shingles near the eyes, or at the top of the nose can be associated with scarring on the cornea, affecting vision.
Shingles on the face can, in rare cases, lead to a temporary hearing loss, facial paralysis and a reduced sense of taste.

Future prospects

Shingles is rarely serious. In about 90 per cent of patients, the attack normally subsides within a week after the appearance of the first symptoms if it gets treated immediately. Otherwise they may suffer for months. Most people only have one or two attacks.
Elderly people in particular may continue to feel intense pain, even after the attack seems to have subsided.These could goes on for months of pain and may cause depression.

Keep the rash uncovered. Try not to scratch. Use calamine lotion to ease the irritation.