What Causes Shingles to Activate?

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Shingles, also known as herpes zoster, is a painful band-like rash caused by reactivation of varicella zoster virus (VZV), the same virus that causes chickenpox. Shingles affects the nerves and skin, causing an itchy, scaly rash that is flat in appearance. Itching these rashes can lead to scarring and scabs on the infected area. 

Shingles are quite common—it is estimated that up to 1 in 3 people will have at least one episode of shingles during their life. VZV usually hangs around harmlessly in the body, but reactivation is more common in those more than 50 years old, with a weakened immune system, or those who are experiencing physical or emotional stress.

This article addresses what causes shingles to activate.

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Shingles Causes

Most people develop shingles after they have recovered from a bout of chickenpox in their childhood. The main culprit, the varicella-zoster virus, remains dormant (inactive) in the nervous system and reactivates when triggered.

The exact triggers of VZV reactivation and the mechanism by which this happens are unknown, but the following risk factors have been shown to put you at higher risk of developing a shingles outbreak:

  • Weakened immune system
  • Being more than 50 years old
  • Experiencing high levels of physical or emotional stress
  • Cancer, especially leukemia and lymphoma

Shingles Symptoms 

Shingles commonly present as a localized rash on the trunk that doesn’t cross the midline of your body. This feature of shingles—in which the rash remains within one or two adjacent bands on the body (dermatomes)—is called localized zoster.

Some people develop pain, itchiness, or tingling in these areas prior to the rash developing. The rash may be flat or form clusters of fluid-filled blisters that progressively dry out and peel off over the course of three to five days.

Additional associated symptoms may include:

  • Fever
  • Headache
  • Photophobia (sensitivity to bright light)
  • Malaise
  • Sensitivity to touch in the affected area
  • Upset stomach

Blisters on the Face

The presence of blisters on your face is a medical emergency and you should seek immediate medical attention. These abrasions can cause:

  • Lasting eye damage and blindness
  • Hearing loss
  • Brief paralysis of the face

In very rare cases, VSV reactivation has been associated with encephalitis—inflammation of the brain. 

Shingles Treatment

Early shingles may be treated with creams and lotions to relieve pain and itching. Using a cool compress may also provide symptomatic relief. Several medications have been shown to be helpful, but their effectiveness is based on the time of initiation, the extent of the disease, and overall health. 

Generally, the earlier you start taking antiretroviral medication such as — acyclovir (Sitavig, Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir) — the better. Early antiretroviral use — taking these medications as soon as you experience pain or see the appearance of a rash — has been shown to shorten the length and severity of the illness. If these medications do not work, your healthcare provider may prescribe the following drugs to help provide relief:

  • Steroid (steroid injections to reduce pain and inflammation)
  • Tricyclic antidepressants
  • Anticonvulsants
  • Capsaicin patches

Can You Get Shingles More Than Once?

VZV usually remains dormant in the body, but about 1 in 3 people who have had chickenpox will have a shingles outbreak in their lifetime. Most people develop shingles at one time in their lives, but it is possible to have more than one outbreak, especially if you have one or more risk factors predisposing you to VZV reactivation.

What Triggers a Shingles Outbreak?

Experts do not know what exactly triggers a shingles outbreak, but it is theorized that high levels of stress and a weakened immune system are two major factors that may play a role in VZV reactivation. In addition, the following risk factors have been shown to put you at higher risk of developing a shingles outbreak:

  • Weakened immune system — this may be the case after taking immunosuppressive medication after an organ transplant, undergoing chemotherapy, contracting HIV or AIDS, developing diabetes, or after a bone marrow transplant
  • Older age, particularly over 50
  • Experiencing high levels of physical or emotional stress
  • Cancer, especially leukemia and lymphoma

Prevention

Vaccination with the recombinant zoster vaccine (RZV), also known as Shingrix, is the single most effective way to prevent shingles and its complications. Getting vaccinated is particularly important for those who are immunocompromised or over 50. Two doses of the Shingrix vaccine have been shown to be 90% effective.

Summary

Shingles, also known as herpes zoster, is a painful rash caused by reactivation of varicella zoster virus (VZV), the same virus that causes chickenpox. 

A Word From Verywell 

Getting the recombinant zoster vaccine is the best method to prevent shingles, especially in those who are over 50 or immunocompromised with a history of chickenpox. 

Shingles is rarely life-threatening, but its symptoms can greatly affect your quality of life. Shingles is common and may go away on its own, but there are ways to reduce your pain and the duration of your symptoms. The sooner you get treated with antiviral medication, the more likely you will avoid serious medical complications like postherpetic neuralgia and nerve damage.

Frequently Asked Questions

  • How does shingles get reactivated?

    Experts do not know what triggers a shingles outbreak, but it is theorized that high levels of stress and a weakened immune system may play a role in VZV reactivation because the immune system loses its ability to keep the virus in check.

  • Can stress trigger a shingles outbreak?

    Large amounts of stress can lower immune function, lowering its ability to defend against viruses like VZV. Therefore, while stress does not directly cause shingles, it is associated with a higher rate of VZV reactivation.

  • Will shingles go away on its own?

    Shingles can go away on its own in two to four weeks, but treatment can ease your symptoms and lower your risk of medical complications like postherpetic neuralgia and nerve damage.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Bricout H, Haugh M, Olatunde O, Gil Prieto R. Herpes zoster-associated mortality in Europe: a systematic review. BMC Public Health. 2015;15:466. doi:10.1186/s12889-015-1753-y

  2. Centers for Disease Control and Prevention. Shingles (herpes zoster) clinical overview.

  3. National Institute of Aging. Shingles.

  4. Izurieta HS, Wu X, Forshee R, et al. Recombinant zoster vaccine (Shingrix): real-world effectiveness in the first 2 years post-licensure. Clin Infect Dis. 2021;73(6):941-948. doi:10.1093/cid/ciab125

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.