The signs and symptoms of shingles usually affect only a small section of one side of your body. These signs and symptoms may include:

• Pain, burning, numbness or tingling
• Sensitivity to touch
• A red rash that begins a few days after the pain
• Fluid-filled blisters that break open and crust over
• Itching

Some people also experience:

• Fever
• Headache
• Sensitivity to light
• Fatigue

Pain is usually the first symptom of shingles. For some, it can be intense. Depending on the location of the pain, it can sometimes be mistaken for a symptom of problems affecting the heart, lungs or kidneys. Some people experience shingles pain without ever developing the rash.

Most commonly, the shingles rash develops as a stripe of blisters that wraps around either the left or right side of your torso. Sometimes the shingles rash occurs around one eye or on one side of the neck or face.

Shingles is caused by the varicella-zoster virus — the same virus that causes chickenpox. Anyone who's had chickenpox may develop shingles. After you recover from chickenpox, the virus can enter your nervous system and lie dormant for years.

Eventually, it may reactivate and travel along nerve pathways to your skin — producing shingles. But, not everyone who's had chickenpox will develop shingles.

The reason for shingles is unclear. But it may be due to lowered immunity to infections as you grow older. Shingles is more common in older adults and in people who have weakened immune systems.

Varicella-zoster is part of a group of viruses called herpes viruses, which includes the viruses that cause cold sores and genital herpes. Because of this, shingles is also known as herpes zoster. But the virus that causes chickenpox and shingles is not the same virus responsible for cold sores or genital herpes, a sexually transmitted infection.

Are you contagious?

A person with shingles can pass the varicella-zoster virus to anyone who isn't immune to chickenpox. This usually occurs through direct contact with the open sores of the shingles rash. Once infected, the person will develop chickenpox, however, not shingles.

Chickenpox can be dangerous for some people. Until your shingles blisters scab over, you are contagious and should avoid physical contact with anyone who hasn't yet had chickenpox or the chickenpox vaccine, especially people with weakened immune systems, pregnant women and newborns.

Anyone who has ever had chickenpox can develop shingles. Most adults in the United States had chickenpox when they were children, before the advent of the routine childhood vaccination that now protects against chickenpox.

Factors that may increase your risk of developing shingles include:

• Being older than 50. Shingles is most common in people older than 50. The risk increases with age. Some experts estimate that half the people age 80 and older will have shingles.
• Having certain diseases. Diseases that weaken your immune system, such as HIV/AIDS and cancer, can increase your risk of shingles.
• Undergoing cancer treatments. Radiation or chemotherapy can lower your resistance to diseases and may trigger shingles.
• Taking certain medications. Drugs designed to prevent rejection of transplanted organs can increase your risk of shingles — as can prolonged use of steroids, such as prednisone.

Complications from shingles can include:

• Postherpetic neuralgia. For some people, shingles pain continues long after the blisters have cleared. This condition is known as postherpetic neuralgia, and it occurs when damaged nerve fibers send confused and exaggerated messages of pain from your skin to your brain.
• Vision loss. Shingles in or around an eye (ophthalmic shingles) can cause painful eye infections that may result in vision loss.
• Neurological problems. Depending on which nerves are affected, shingles can cause an inflammation of the brain (encephalitis), facial paralysis, or hearing or balance problems.
• Skin infections. If shingles blisters aren't properly treated, bacterial skin infections may develop.