What Actually Causes Shingles—and How You Can Prevent It

It's estimated that one million people in the United States get shingles every year. Shingles is a disease caused by a reactivation of the varicella-zoster virus—the virus that causes chickenpox.

While not everyone who has chickenpox as a kid will see it reappear as shingles as an adult, one in three people will experience shingles over the course of a lifetime. But what exactly causes the reactivation of the virus? And how can you prevent it?

What Are the Symptoms of Shingles?

Shingles symptoms begin several days before a rash appears as an itching, burning, or tingling feeling. "The hallmark of shingles is that there is pain that precedes the rash," said David Cutler, MD, a family medicine physician at Providence Saint John's Health Center. "This can be confusing for people who go to the doctor with pain and no rash. This can mean your shingles diagnosis will be missed."

You then develop a painful rash that consists of blisters that usually appear as a stripe around the left or right side of the body. The rash scabs over in seven to 10 days and can sometimes be accompanied by:

• Fever
• Headache
• Chills
• Upset stomach

These blisters appear on a path of the nerve that the virus is extending along. "However, most people don't know where the paths of various nerves are," said Dr. Cutler. "But if you've had sciatica or a pinched nerve in your neck going down your arm, those are the patterns shingles will take."

Occasionally blisters from shingles will appear on your face or get into your eyes, which is much more dangerous and requires immediate treatment since it can lead to vision problems or vision loss.

What Causes Shingles?

If you have had chickenpox before, you have the virus that causes chickenpox (varicella-zoster) in your body. Even after you recover, the virus is stored in your body and can reactivate anytime. When it's reactivated, it turns into shingles.

"While the exact cause of shingles is unknown, experts do know that the virus can remain inactive in nerve tissues near the spinal cord and brain for decades," said Eric Grahling, MD, a pain management expert at Comprehensive Pain Management of Central Connecticut. "We believe that it may recur so many years later if a person has a lowered immunity due to infections that comes with age or has a weakened immune system due to medical treatments or a disease."

Many people don't remember having chickenpox in the past. If you were born in the US before 1980, you likely were exposed to chickenpox since more than 99% of people born before 1980 in the US had chickenpox.

It's important to speak to a healthcare provider if you don't remember having chickenpox. They can make sure you get a varicella titer test that can tell you if you've been exposed to the virus in the past.

How Can You Reduce the Risk of Shingles?

Luckily, shingles is preventable. There is an effective vaccine, and if you do develop shingles, there are a few ways you can prevent the virus from spreading to another person.

Get a Shingles Vaccine

Zostavax, approved in 2006, used to be the only shingles vaccine available. But as of 2017, Shingrix was approved by the FDA and is the preferred vaccine choice. Shingrix is said to be over 90% effective. It's recommended you get the Shingrix vaccine if you are:

• 50 years old or older
• 19 years old or older and have a weakened immune system

You'll get two doses of Shingrix, scheduled two to six months apart. Sometimes, people with weakened immune systems can get the second dose one to two months apart.

"It's important to note that you should also get Shingrix even if you had Zostavax, the older shingles vaccine," Dr. Cutler said. "You should also get it if you already had shingles or don't know if you had chickenpox as a child." Since it is possible to get shingles more than once.

Shingles Is Contagious, but You Can Help Prevent Its Spread

A shingles outbreak is contagious. You can pass the virus to anyone who isn't immune to chickenpox if that person has direct contact with your shingles sores. If a person becomes infected, they will develop chickenpox, not shingles—but they can still develop shingles later in life.

So until your shingles blisters scab over, try to avoid contact with the following groups of people:

• Pregnant people (who haven't had chickenpox or a chickenpox vaccine)
• People with a weakened immune system
• Premature or low birth weight infants

You should also practice good hand hygiene, cover the rash, and avoid touching or scratching the rash. The risk of spreading the virus is low if you keep the rash covered.

What Are the Complications of Shingles?

Ideally, healthcare providers are hoping to prevent adults from ever getting shingles, and, ultimately, shingles-related complications such as:

• Vision loss
• Pneumonia
• Hearing problems
• Brain inflammation (encephalitis)
• Ongoing nerve pain called postherpetic neuralgia (PHN)
• Death

"Thankfully, most shingles cases are highly treatable," said Dr. Grahling. "However, the dreaded consequence of shingles is the extreme pain known as postherpetic neuralgia (PHN), which can persist for months or even years." PHN can affect up to 10–18% of those who have experienced shingles.

If you're experiencing symptoms, there is hope for treatment, but you have to get help—fast. "You'll want to see a pain management specialist as soon as possible," Dr. Grahling said. "You'll receive the appropriate medications and the advanced injection therapies available that can help prevent this ruthlessly painful condition—in this case, time is of the essence in treating this."

A Quick Review

Shingles is caused by the reactivation of the varicella-zoster virus, which causes chickenpox. The reactivation of the virus may occur as a result of lowered immunity. This may be due to infections, age, or having a weakened immune system due to medical treatments or disease.

People 50 years and older or 19 years and older with a weakened immune system should strongly consider getting the shingles vaccine, called Shingrix, to protect themselves against shingles.