How shingles develops in your body

You get shingles when the varicella-zoster virus — the same virus that causes chickenpox — wakes up inside nerve cells where it has been dormant for years or decades. The virus does not spread to you from someone else who has shingles. Instead, it reactivates from your own body's nerve tissue, usually along one side of your torso, face, or limbs.

After you recover from chickenpox, the virus does not leave your body completely. It retreats into nerve bundles called dorsal root ganglia and stays there in an inactive state. For reasons doctors do not fully understand, the virus can reactivate later in life and travel along the nerve to cause shingles. This reactivation typically happens only once, though a small number of people experience it twice.

The virus causes inflammation and damage to the nerve, which is why shingles produces pain, burning, and a blistering rash in a specific band or stripe across your skin. The rash usually appears on one side of the body and follows the path of the affected nerve.

Key Takeaways

  • Shingles comes from the same virus that causes chickenpox, which reactivates from dormant nerve cells in your body years or decades later.
  • You cannot catch shingles from another person, but someone who has never had chickenpox can catch chickenpox from a person with shingles.
  • A weakened immune system is the strongest known risk factor, which is why shingles is more common after age 50 and in people with certain medical conditions.
  • Physical or emotional stress, injury to the affected nerve area, and certain medications can trigger reactivation in people at risk.
  • The shingles vaccine significantly reduces your risk of developing the condition and can prevent severe complications if you do get it.

Why your immune system matters most

Your immune system normally keeps the dormant virus in check. When your immune system weakens — whether from age, illness, or medication — the virus can break through and reactivate. This is why shingles becomes much more common after age 50, when immune function naturally declines.

People with conditions that weaken immunity face higher risk. These include HIV, cancer, organ transplant, rheumatoid arthritis, and lupus. People taking medications that suppress the immune system — such as corticosteroids or biologics for autoimmune disease — also have increased risk. Even temporary immune suppression from a severe infection or major surgery can trigger shingles.

Age is the single strongest predictor. About one in three people over age 60 will develop shingles at some point in their life. The risk rises further after age 70. However, shingles can occur at any age, even in people with healthy immune systems.

Stress, injury, and other triggers

Beyond immune weakness, certain events can trigger reactivation in people already at risk. Significant physical or emotional stress — from illness, surgery, grief, or major life changes — sometimes precedes shingles by days or weeks. Trauma or injury to the area where the rash later appears may also play a role, though the connection is not fully understood.

Some medications increase risk. Immunosuppressants used after organ transplant or for autoimmune disease are the most common culprits. Certain cancer treatments can also raise the risk of shingles during or shortly after therapy.

Having a trigger does not mean you will definitely develop shingles. Many people experience stress or injury without ever getting the condition. Triggers matter most in people whose immune systems are already compromised.

Who is most likely to develop shingles

Your risk of shingles depends on several factors working together. Age is the foundation: the older you are, the higher your risk. But other conditions and circumstances layer on top of that baseline risk.

People at highest risk include those over 50, especially those over 70; people with HIV or AIDS; people who have had cancer or are undergoing cancer treatment; people who have had an organ or bone marrow transplant; and people taking long-term corticosteroids or other immune-suppressing medications. Pregnant people can develop shingles, though it is uncommon. People with a history of chickenpox are at risk — which includes nearly all adults born before the chickenpox vaccine became routine in the 1990s.

If you have never had chickenpox and were not vaccinated against it, you cannot develop shingles because you do not carry the dormant virus. However, this group is small in the United States, since chickenpox was very common before vaccination.

What happens if you are exposed to someone with shingles

You cannot catch shingles from another person. The virus in shingles blisters is not contagious in the way that chickenpox is. However, if you have never had chickenpox and have not been vaccinated against it, you can catch chickenpox from someone with active shingles. This is because the virus in the shingles rash is the same varicella-zoster virus that causes chickenpox.

If you are exposed to shingles and have never had chickenpox, avoid direct contact with the rash until it crusts over — usually about 7 to 10 days after it appears. Keeping the rash covered also reduces transmission risk. Once you recover from chickenpox, you will then carry the dormant virus and could potentially develop shingles later in life.

If you already had chickenpox or are vaccinated against it, exposure to someone with shingles poses no risk to you. Your immune system already recognizes the virus.

The role of the shingles vaccine

The shingles vaccine (Shingrix) works by training your immune system to recognize and fight the varicella-zoster virus before it reactivates. The vaccine does not contain the live virus, so it cannot cause shingles. It is given as two shots, two to six months apart.

The vaccine is recommended for all adults age 50 and older, regardless of whether they remember having chickenpox. It is also recommended for certain younger adults with weakened immune systems or specific medical conditions. Studies show that Shingrix prevents shingles in about 90 percent of vaccinated people and reduces the severity of the condition in those who do develop it despite vaccination.

If you have already had shingles, you can still benefit from the vaccine. It reduces the risk of shingles recurring and lowers the chance of long-term nerve pain after shingles. You should wait until the rash has completely crusted over before receiving the vaccine.

Frequently Asked Questions

Can I get shingles more than once?

Most people who have shingles will never have it again. However, recurrence is possible, especially in people with weakened immune systems. If you do develop shingles a second time, it usually appears in a different location on your body than the first episode.

If I get the shingles vaccine, can I still develop shingles?

The vaccine is highly effective but not 100 percent protective. About 10 percent of vaccinated people may still develop shingles, but their symptoms are usually much milder and recovery is faster. The vaccine also significantly reduces the risk of long-term nerve pain, which is one of the most bothersome complications.

Is shingles contagious before the rash appears?

No. Shingles is only contagious when the blisters are open and leaking fluid. Once the rash crusts over, the virus is no longer spread through contact. The pain and tingling that occur before the rash appears are not contagious.

Can children get shingles?

Shingles is rare in children but can occur, especially in those with weakened immune systems or those who had chickenpox before age one. Children who received the chickenpox vaccine are at very low risk of developing shingles.

Does the chickenpox vaccine prevent shingles?

The chickenpox vaccine protects against chickenpox infection. People vaccinated against chickenpox have a lower risk of developing shingles later in life compared to people who had the natural chickenpox infection, but the shingles vaccine (Shingrix) is more effective at preventing shingles in older adults.