You don’t catch shingles from another person the way you catch a cold or the flu. Shingles develops from a virus already inside your body, one that’s been quietly sitting in your nerve cells since you had chickenpox, potentially decades earlier. About 1 in 3 people in the United States will develop shingles at least once in their lifetime, making it remarkably common despite its unusual origin story.
The Virus That Never Leaves
Shingles is caused by the varicella-zoster virus, the same virus responsible for chickenpox. After you recover from chickenpox, the virus doesn’t get cleared from your body. Instead, it retreats into clusters of nerve cells called ganglia, located along your spine and at the base of your skull. There it enters a dormant state, shutting down its ability to reproduce and essentially going silent.
The virus can remain hidden in these nerve cells for decades. Researchers have detected viral DNA in nerve tissue obtained at autopsy from people who had chickenpox many years before death. During dormancy, the virus maintains only minimal activity, keeping a single regulatory gene switched on while everything else stays quiet. Your immune system doesn’t eliminate the virus during this period. The virus essentially represses its own replication through an internal mechanism, not because your immune system is actively fighting it off.
What Triggers Reactivation
Shingles happens when the dormant virus “wakes up” and begins reproducing again. It then travels along nerve fibers from the ganglia back out to the skin, where it causes the characteristic painful, blistering rash. This rash typically appears in a band or strip on one side of the body, following the path of the nerve where the virus was hiding.
The most significant trigger is a weakening of your immune system. This can happen through:
- Aging: Your immune defenses naturally decline over time, which is why shingles is far more common after age 50.
- Immune-suppressing conditions: HIV, certain cancers, and autoimmune diseases all raise your risk.
- Medications: Drugs that deliberately suppress the immune system, such as those used after organ transplants or for autoimmune conditions, can trigger reactivation. In animal studies, treatment with immune-suppressing drugs alone caused reactivation in 75% of subjects.
- Physical and emotional stress: Severe stress has been linked to reactivation in both human and animal research.
Not everyone who reactivates the virus has an obvious trigger. Sometimes shingles appears in otherwise healthy people with no clear explanation.
Can You Catch Shingles From Someone?
You cannot catch shingles directly from another person. However, if you’ve never had chickenpox and never received the chickenpox vaccine, you can catch the varicella-zoster virus from someone with an active shingles rash. In that case, you’d develop chickenpox first, not shingles. The virus would then go dormant in your nerve cells, and you could develop shingles later in life.
Transmission happens through direct contact with the fluid inside shingles blisters or by breathing in virus particles released from those blisters. A person with shingles is contagious from the time the blisters appear until they fully crust over and dry out. Once the blisters are completely crusted, the risk of spreading the virus drops significantly.
In healthcare settings, the risk is taken seriously. Patients with widespread (disseminated) shingles can spread the virus through the air, not just through blister contact. This is why hospitals treat these cases with the same precautions used for chickenpox.
You Need a Prior Infection First
The prerequisite for shingles is having the varicella-zoster virus already in your body. That means you must have had chickenpox at some point or received the live chickenpox vaccine, which contains a weakened form of the same virus. Many adults who believe they never had chickenpox actually had a mild or subclinical case in childhood that went unnoticed, which is why shingles can seem to appear “out of nowhere.”
If you’ve truly never been exposed to varicella-zoster virus in any form, you cannot develop shingles. Your nerve cells would have no dormant virus to reactivate.
Can You Get Shingles More Than Once?
Most people experience shingles only once, but recurrence is possible. Estimates range from about 1% to nearly 10% of people having more than one episode. Those with weakened immune systems face higher odds of recurrence. Having shingles once does not clear the virus from your nerve cells, so the potential for another episode remains.
Reducing Your Risk
The shingles vaccine (Shingrix) is currently recommended for adults 50 and older, given as two doses separated by two to six months. Adults 19 and older with weakened immune systems also qualify and can receive their second dose as early as one to two months after the first. A large study found that two doses were 76% effective at preventing shingles, while a single dose provided 64% effectiveness. For immunocompromised individuals, the vaccine was 65% effective.
Beyond vaccination, the factors that keep your immune system functioning well are the same ones that help keep the virus dormant: managing chronic stress, getting adequate sleep, and staying on top of any conditions that affect immune function. None of these guarantee prevention, but they reduce the odds that the virus hiding in your nerve cells will find an opportunity to reactivate.