Why do you get shingles

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Last updated: April 8, 2026

Quick Answer: Shingles occurs when the varicella-zoster virus, which causes chickenpox, reactivates after lying dormant in nerve tissue. The risk increases significantly with age, affecting about 1 in 3 people in the United States during their lifetime, with over 99% of adults over 50 having been exposed to the virus. The CDC recommends two doses of the Shingrix vaccine for adults 50+ and immunocompromised adults 19+, which is over 90% effective at preventing shingles.

Key Facts

Shingles is caused by reactivation of the varicella-zoster virus (VZV), the same virus that causes chickenpox
About 1 in 3 people in the U.S. will develop shingles in their lifetime according to CDC data
Risk increases significantly after age 50, with about half of cases occurring in people 60+
The Shingrix vaccine, approved in 2017, is over 90% effective at preventing shingles
Postherpetic neuralgia, a painful complication, affects 10-18% of shingles patients

Overview

Shingles, medically known as herpes zoster, is a viral infection characterized by a painful rash that typically appears as a stripe of blisters on one side of the body. The condition has been recognized since ancient times, with descriptions dating back to Hippocrates in ancient Greece who called it "herpes" meaning "to creep." The connection between chickenpox and shingles was established in the late 19th century by Hungarian physician János Bókay, but it wasn't until 1953 that Thomas Weller isolated the varicella-zoster virus. In the United States, approximately 1 million cases occur annually, with incidence increasing with age. Before the chickenpox vaccine was introduced in 1995, nearly all children contracted chickenpox, creating a large reservoir of people at risk for shingles later in life. The economic burden is substantial, with direct healthcare costs estimated at $1 billion annually in the U.S. alone.

How It Works

After a person recovers from chickenpox, the varicella-zoster virus doesn't leave the body but instead becomes dormant in sensory nerve ganglia near the spinal cord and brain. The virus can remain inactive for decades, kept in check by the immune system. When immune function declines due to aging, stress, illness, or medications, the virus can reactivate. It travels along nerve pathways to the skin, causing the characteristic painful rash. The reactivation typically affects a single dermatome - a specific area of skin supplied by a single spinal nerve. This explains why shingles usually appears as a band or strip on one side of the body. The most common locations are the torso (50% of cases), face (including eyes in 10-25% of cases), and neck. The rash progresses through stages: first redness, then fluid-filled blisters that eventually crust over, usually healing within 2-4 weeks.

Why It Matters

Shingles has significant public health implications due to its prevalence and potential complications. Postherpetic neuralgia, the most common complication, causes severe nerve pain that can persist for months or years after the rash clears, affecting quality of life and daily functioning. Other serious complications include vision loss if the eye is involved, neurological problems, skin infections, and rarely, pneumonia or encephalitis. The introduction of the Shingrix vaccine in 2017 marked a major advancement, reducing shingles incidence by over 90% in clinical trials. Vaccination is particularly important for older adults and immunocompromised individuals who face higher risks. Understanding shingles helps healthcare providers identify early symptoms, initiate prompt antiviral treatment within 72 hours of rash onset, and prevent transmission to vulnerable individuals who haven't had chickenpox or been vaccinated.