<p>From mayoclinic.com:</p>
<p>Shingles — also known as herpes zoster — is a viral infection that causes a painful rash.</p>
<p>Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox. After you've had chickenpox, the virus lies dormant in your nerves. Years later, the virus may reactivate as shingles.</p>
<p>Although painful, typically shingles isn't a serious condition. Sometimes, however, the rash can lead to a debilitating complication called postherpetic neuralgia. This condition causes the skin to remain painful and sensitive to touch for months or even years after the rash clears up.</p>
<p>Early treatment can help shorten a shingles infection and reduce the risk of complications.</p>
<p>Shingles is a second eruption of the varicella-zoster virus — the same virus that causes chickenpox.</p>
<p>Varicella-zoster is part of a group of viruses called herpes viruses, which includes the viruses that cause cold sores and genital herpes. Many of these viruses can lie hidden in your nervous system after an initial infection and remain dormant for years before causing another infection.</p>
<p>Anyone who's had chickenpox may develop shingles. If your immune system doesn't destroy the entire virus during the initial infection, the remaining virus can enter your nervous system and lie hidden for years. Eventually, it may reactivate and travel along nerve pathways to your skin — producing shingles.</p>
<p>The reason for the encore is unclear. Shingles is more common in older adults and those who have weak immune systems.</p>
<p>About one in 10 healthy adults who've had chickenpox eventually develop shingles, usually after age 50. Most people develop shingles only once, but recurrences in other areas are possible.</p>
<p>A person with shingles can pass the varicella-zoster virus to anyone who hasn't had chickenpox before. This usually occurs through direct contact with the open sores of the shingles rash. Once infected, the person will develop chickenpox, however, not shingles. The infection can be serious for certain groups of people with immune system deficiencies.</p>
<p>Until the shingles blisters scab over, avoid physical contact with:</p>
<pre><code>* Anyone who's never had chickenpox
* Anyone who has a weak immune system
* Newborns
* Pregnant women (A chickenpox infection can be dangerous for a developing baby.)
</code></pre>
<p>For about one in five people who develop shingles, the pain continues in the same spot long after the blisters have cleared. This condition is known as postherpetic neuralgia.</p>
<p>When you have postherpetic neuralgia, damaged nerve fibers send confused and exaggerated messages of pain from your skin to your brain. This leaves the affected area of skin sensitive to even the slightest touch. For some people, the brush of clothing or a breeze can be excruciatingly painful.</p>
<p>Pain medication, antidepressants or anticonvulsant medications may help provide relief until the pain subsides.</p>
<p>Shingles can also lead to other complications, including inflammation of the brain (encephalitis) and other neurological problems. If shingles occurs on your face, it can cause hearing problems and temporary or permanent blindness. Loss of facial movement (paralysis) is possible as well. If blisters aren't properly treated, bacterial skin infections are another potential problem.</p>