Causes and Risk Factors of Shingles

In This Article
Table of Contents

Shingles results from reactivation of the varicella zoster virus (VZV), which, when it first infects the body, causes chickenpox and then goes into hiding in the nervous system. Why the virus re-emerges isn't entirely understood, but there are theories. 

Shingles is most common in older people, but anyone with the varicella zoster virus is at risk.

In fact, reduced immunity is considered the biggest risk factor for shingles. Researchers believe that stress could also play a role for some people.

Shingles is an especially unpleasant illness. It causes a painful and unsightly skin rash, as well as potential long-term complications, the most common one being a condition known as postherpetic neuralgia (PHN), which is characterized by a burning sensation where the shingles rash once was. That's why it's important to understand what causes chickenpox, who's most at risk of coming down with it, and how to protect yourself if you're exposed.

shingles risk factors
© Verywell, 2018 

Virus Reactivation

After a person recovers from chickenpox, the symptoms disappear but the varicella virus that caused it retreats to cells in the nervous system, where it can hang out for decades without causing problems.

When the virus re-emerges, it typically reactivates in clusters of nerve cells in the peripheral nervous system called a sensory ganglion. The ganglia most likely to host varicella are those in the cervical, thoracic, and lumbar spine.

Varicella also often affects the trigeminal ganglion that provides sensation to the face. As its name suggests, this particular clump of nerves has three branches. The one associated with eye function, the ophthalmic branch, is 20 times more likely than the other two to be affected.

The area with the particular nerve cells in which the virus reawakens is where the shingles symptoms—extreme pain, unsightly rash—will be concentrated.

Since the nervous system consists of tree-like branches of nerves, the blisters will follow the particular path of the nerves affected. That's why a shingles rash often resembles a swath of blisters in a very specific area, rather than spread all over the body (as in chickenpox).

Shingles Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Old Man

Common Causes

What prompts the varicella virus to reactivate isn't entirely understood. The virus is a member of the same family of microbes that cause herpes infections, such as genital herpes and cold sores, which also tend to come and go, so it's not surprising that varicella would behave similarly. The big difference is, while herpes infections can recur multiple times, most people only experience shingles once.

In any event, there are two main causes of shingles:

Weakened Immune System

There is a clear association between shingles and weakened immunity to infection.  Even though the varicella virus is not invading the body for the first time, the immune system still is responsible for keeping it at bay. Sometimes, however, it's unable to do that.

What this means is that the varicella virus, which after causing the chickenpox rash in the skin had traveled to ganglia in the nervous system, becomes active again and heads back to the skin. Since it travels along the nervous system, the rash stays on one side of the body and appears in the shape of a strip or band that aligns with the shape of the nerves below the skin. 

Stress

There's a long-held hypothesis that chronic stress or even a single episode of emotional distress can trigger the dormant varicella virus to become active again and bring on a shingles outbreak. Given that stress often is linked to any number of changes in health, including gastrointestinal problems, migraines, and eczema, this notion is not at all far-fetched.

In fact, there is some evidence to support it. For example, an often-cited 1998 study of otherwise healthy adults over 60 found that those who had had shingles were more than twice as likely to have had a negative life event within six months of the outbreak as peers who didn't have shingles. When asked about events within the past two to three months specifically, those in the shingles group reported the same amount of negative life events as their unaffected counterparts. This suggests that perceiving an event as stressful, rather than the event itself, may be linked to increased rate of shingles.

More recent research has largely supported this concept. Some have taken this to mean that the overall perception of stress and the ability to cope with it, may add to the underlying factors that create the perfect storm for a shingles outbreak.

Risk Factors

Since compromised immunity is the most common trigger for a latent varicella virus to become active, any factor associated with a weakened immune system can increase the risk of shingles. Important risk factors for shingles include:

  • Being 50 or over. With age, there is a natural decline in cell-mediated immunity.
  • Infection from human immunodeficiency virus (HIV). Although most people who develop shingles have the infection just once, it's not uncommon for someone with HIV to have recurrent shingles infections.
  • A chronic medical condition. Cancer (especially leukemia or lymphoma) or diabetes are examples.
  • Medication that suppresses the immune system. Some examples of these include chemotherapy drugs and systemic steroids, such as prednisone.
  • Having an organ transplant. The medications that are necessary for preventing organ rejection suppress the immune response. 

Note that many of these risk factors are as likely to apply to young people and children as they are to older people. So, even though shingles often is regarded as an illness of advancing age, this isn't always the case.

Was this page helpful?

Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Harpaz R, Leung JW, Brown CJ, Zhou FJ. Psychological stress as a trigger for herpes zoster: might the conventional wisdom be wrong?. Clin Infect Dis. 2015;60(5):781-5.

  2. Nair PA, Patel BC. Herpes Zoster (Shingles) [Updated 2019 May 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441824/

  3. Shrestha M, Chen A. Modalities in managing postherpetic neuralgiaKorean J Pain. 2018;31(4):235–243. doi:10.3344/kjp.2018.31.4.235

  4. Gilden D, Nagel M, Cohrs R, Mahalingam R, Baird N. Varicella Zoster Virus in the Nervous SystemF1000Res. 2015;4:F1000 Faculty Rev-1356. Published 2015 Nov 26. doi:10.12688/f1000research.7153.1

  5. Gilden D, Mahalingam R, Nagel MA, Pugazhenthi S, Cohrs RJ. Review: The neurobiology of varicella zoster virus infectionNeuropathol Appl Neurobiol. 2011;37(5):441–463. doi:10.1111/j.1365-2990.2011.01167.x

  6. Sampathkumar P, Drage LA, Martin DP. Herpes zoster (shingles) and postherpetic neuralgiaMayo Clin Proc. 2009;84(3):274–280. doi:10.1016/S0025-6196(11)61146-4

  7. Cohen KR, Salbu RL, Frank J, Israel I. Presentation and management of herpes zoster (shingles) in the geriatric populationP T. 2013;38(4):217–227.

  8. Gilden D, Cohrs RJ, Mahalingam R, Nagel MA. Neurological disease produced by varicella zoster virus reactivation without rashCurr Top Microbiol Immunol. 2010;342:243–253. doi:10.1007/82_2009_3

  9. National Institute of Neurological Disorders and Stroke. Singles: Hope Through Research. August 13, 2019

  10. Schmader K, George LK, Burchett BM, Hamilton JD, Pieper CF. Race and stress in the incidence of herpes zoster in older adults. J Am Geriatr Soc. 1998;46(8):973-7.

  11. Rafael Harpaz, Jessica W. Leung, Cedric J. Brown, Fang Jun Zhou, Psychological Stress as a Trigger for Herpes Zoster: Might the Conventional Wisdom Be Wrong?Clinical Infectious Diseases, Volume 60, Issue 5, 1 March 2015, Pages 781–785, https://doi.org/10.1093/cid/ciu889

  12. Kawai K, Yawn BP. Risk Factors for Herpes Zoster: a Systematic Review and Meta-AnalysisOpen Forum Infect Dis. 2017;4(Suppl 1):S313–S314. Published 2017 Oct 4. doi:10.1093/ofid/ofx163.733

  13. Oxman MN. Herpes zoster pathogenesis and cell-mediated immunity and immunosenescence. J Am Osteopath Assoc. 2009;109(6 Suppl 2):S13-7.

  14. Hansson E, Forbes HJ, Langan SM, Smeeth L, Bhaskaran K. Herpes zoster risk after 21 specific cancers: population-based case-control studyBr J Cancer. 2017;116(12):1643–1651. doi:10.1038/bjc.2017.124

  15. Pavlopoulou ID, Poulopoulou S, Melexopoulou C, Papazaharia I, Zavos G, Boletis IN. Incidence and risk factors of herpes zoster among adult renal transplant recipients receiving universal antiviral prophylaxisBMC Infect Dis. 2015;15:285. Published 2015 Jul 24. doi:10.1186/s12879-015-1038-1

Additional Reading