When the varicella-zoster virus reactivates, it travels along a specific nerve path. This means you may see a shingles rash develop in one or more areas innervated by that nerve. This skin area along the nerve path is known as a dermatome.

Shingles, also called herpes zoster, is caused by a reactivation of the varicella-zoster virus, the same virus that causes chickenpox.

The virus usually stays dormant for years in your nerve cells after you’ve had chickenpox. If it reawakens, the virus moves through specific nerve pathways until it reaches your skin layers. When that happens, you see a blistering rash that leaves a linear footprint and causes pain and itchiness.

The rash can appear on any part of your body but typically on one side of your trunk or torso. The location of a shingles rash depends on which nerve the virus spreads from in your body. Usually, the rash is contained in one or two areas of your skin or dermatomes.

If you have not had chickenpox, you may develop it if you come in direct contact with someone’s active shingles rash. If you have had chickenpox and become exposed to the virus, you may develop shingles instead.

When you get the varicella-zoster virus the first time, you develop chickenpox symptoms. Once you get better, the virus stays in your body in an inactive form. It usually remains dormant in your cranial nerves and spinal ganglia. Spinal ganglia are nerve cells that connect your spinal cord to the nerves in your body and limbs.

If the varicella-zoster virus reactivates years later, it starts spreading down your sensory nerve fibers from your spinal cord to areas of your skin. This is known as shingles.

Nerves carry sensory information. They send messages of pain, itchiness, or pressure from your skin to your spinal cord and brain.

When the virus travels along a nerve and eventually reaches your skin, it often causes a painful and itchy rash. Besides this visible rash made of tiny blisters, the virus also causes sensations along that nerve pathway, like burning pain, pins and needles, and itchiness. These sensations are also possible when shingles manifests without a rash.

Shingles may last up to 5 weeks.

You can learn more about early signs of shingles here.

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Shingles Dermatomes. Illustration by Alexis Lira.

A dermatome is an area of your skin where the sensation is supplied by one spinal nerve.

You have 31 spinal nerves on each side of your body that help send information between your body and spine. Each nerve is associated with a dermatome except for the C1 spinal nerve in your neck.

For example, the C5 spinal nerve on the right side of your body is responsible for delivering sensory information from your right collarbone and upper shoulder to your spinal cord and brain. All the skin in this region is one dermatome.

Shingles rashes form along one or two dermatomes on one side of your body. Their location depends on which nerve the virus spreads from. The rash doesn’t cross the midline of your body because each spinal nerve supplies sensory information only for the left or right side of your body.

Shingles causes inflammation and temporary impairment in your nerves, which in turn results in symptoms like burning pain, itching, numbness, and a rash. As the herpes zoster virus continues to travel along your sensory nerves, it can also cause more severe damage and inflammation, even after your rash disappears. Many shingles complications are associated with this damage.

You can read more about shingles pain here.

Postherpetic neuralgia

The most common long-term complication of shingles is postherpetic neuralgia. It refers to pain or itchiness that lasts weeks or months after a shingles rash has resolved. It is due to nerve damage.

Most people recover from postherpetic neuralgia within a year, but in some cases, it can be permanent.

Motor nerve damage

The herpes zoster virus can also affect the nerves that help you move your muscles. It’s thought that about 0.5–5% of people with shingles develop segmental zoster paresis. This condition leads to weakness in the muscles around the shingles rash.

Cranial nerve damage

In some cases, the herpes zoster virus affects one of the major nerves in your head called cranial nerves. Less than 1% of shingles cases affect cranial nerve 7 (facial nerve), leading to shingles on the face. A complication of this is the Ramsay Hunt syndrome.

This syndrome may cause symptoms like:

Medications are the most common treatment for long-term pain and weakness associated with nerve damage. Treatment for shingles focuses on reducing the severity and duration of symptoms and lowering the chance of complications. If complications like nerve damage are present, a healthcare professional may recommend the following:


Anticonvulsants, such as gabapentin and pregabalin, are approved by the Food and Drug Administration (FDA) to treat postherpetic neuralgia. These drugs bind to calcium channels and influence neurotransmitter release to relieve pain.


A wide range of antidepressants may be used at low dosages to help manage pain. One group of antidepressants commonly used for this purpose is tricyclic antidepressants. These drugs inhibit the reuptake (reabsorption) of serotonin and norepinephrine.

Topical local anesthetics

Two types of creams are commonly used to help manage nerve pain. Lidocaine is FDA-approved specifically for treating postherpetic neuralgia.

Capsaicin cream is available over the counter and is somewhat effective, but many people experience burning pain while putting it on.

A healthcare professional may also prescribe pain-relieving medications.

The chickenpox virus can remain dormant in your nerves for years and then reactive in the form of shingles. Once reawakened, the virus spreads to your skin and travels along specific nerve pathways. A shingles rash will appear in the area that specific nerve controls.

Because the shingles virus travels along nerves, and these send pain, pressure, and temperature information to your brain, the condition tends to be painful and uncomfortable. You will also notice the rash follows a line, usually along one or two nerve pathways on one side of the face or body.