Rarely, the virus that causes shingles can cause neurological complications like encephalitis. Early diagnosis and treatment are key to improving the outlook for a person with this condition.

Shingles is a painful rash that typically develops in older adults or people who are immunocompromised. It’s caused by the varicella-zoster virus (VZV), which is the same virus that causes chickenpox.

In rare cases, VZV can cause neurological complications like encephalitis. Encephalitis is inflammation of the brain. It’s a serious condition that can cause long-term neurological damage and, in some cases, even death.

Here’s what you need to know about the connection between shingles and encephalitis, including symptoms, diagnosis, treatment, and outlook.

The virus VZV causes shingles and chickenpox. It typically causes chickenpox in childhood and then remains dormant in the body. Years later, it can become active again, causing the painful rash known as shingles.

When VZV reactivates, it may also spread into the central nervous system. This can cause neurological disorders like encephalitis. However, this complication is rare.

According to the World Health Organization, encephalitis occurs in 1 in 33,000–50,000 cases of VZV. Other research estimates that VZV encephalitis affects 0.1–0.2% of people with VZV.

Encephalitis caused by VZV is also called “herpes zoster encephalitis” or “VZV encephalitis.” This helps distinguish it from other causes of encephalitis, such as:

  • infection with herpes simplex virus (HSV), the most common cause of viral encephalitis
  • mosquito- or tick-borne viruses
  • bacterial or fungal infections
  • problems with the immune system

VZV encephalitis typically occurs in people with active shingles, although it may occur before or after the rash. Rarely, it can occur without the appearance of a rash.

The risk of developing VZV encephalitis is higher for people who are immunocompromised. This can include:

  • adults older than 50 years of age
  • people living with an immunodeficiency disorder, such as HIV
  • people receiving anticancer treatments
  • people who have had an organ transplant

A 2020 case report and research review indicated that in very rare cases, VZV encephalitis can develop in children or people with healthy immune systems. More research is needed to understand why this happens.

Symptoms of VZV encephalitis often begin as mild, flu-like symptoms. This can include:

  • headache
  • fever
  • vomiting
  • aching muscles and joints
  • neck stiffness

In addition, people with VZV encephalitis often experience changes in mental status, such as disorientation, confusion, or altered personality or behavior.

Medical Emergency

Encephalitis is a serious medical condition that can progress rapidly, causing long-term neurological damage and even death. Early diagnosis and treatment in a hospital are critical.

Get emergency medical treatment if you notice any of the following signs or symptoms of severe encephalitis:

  • personality changes
  • problems with speech or hearing
  • double vision
  • hallucinations
  • seizures
  • loss of consciousness
  • muscle weakness
  • memory loss
  • loss of sensation in parts of the body

To diagnose encephalitis, a doctor will start by performing a physical exam and reviewing your medical history, including medication use and preexisting medical conditions.

They may also ask about any activities during the past days or weeks involving:

  • exposure to insects, ticks, or animals
  • contact with people who were sick
  • recent travel

If your doctor suspects VZV encephalitis, they may perform or order the following diagnostic tests:

  • physical examinations to assess motor and sensory function, nerve function, and mental status
  • laboratory screening of blood, urine, and body secretions to help detect brain or spinal cord infection
  • polymerase chain reaction (PCR) testing to detect viral infections such as VZV in the cerebrospinal fluid
  • CT or MRI scan to assess inflammation of the brain

People who receive a diagnosis of encephalitis need immediate treatment to help prevent disease progression and brain damage.

The standard treatment for VZV encephalitis is the antiviral drug acyclovir, which can help slow the progression and spread of the virus.

Acyclovir will be administered intravenously (through an IV) in a hospital. The typical treatment duration is:

  • 7 days in people who are immunocompetent
  • 10–14 days in people who are immunocompromised

Common side effects of acyclovir include nausea, vomiting, and diarrhea. Rare but serious side effects can include hallucinations, confusion, and seizures. Speak with your doctor if you experience any severe side effects.

Other treatments to help manage the symptoms of VZV encephalitis may include:

  • IV fluids to help prevent dehydration
  • pain relievers
  • support for airway, breathing, and circulation
  • medications to manage seizures
  • steroids, such as prednisone, to help reduce inflammation of the blood vessels (vasculopathy)
  • a breathing tube, urinary catheter, or feeding tube if loss of consciousness occurs

Most people who have shingles do not develop encephalitis. Encephalitis is a rare complication affecting only 0.1–0.2% of people with VZV.

Some people have a greater risk of complications from VZV, such as shingles and encephalitis. This includes:

If you are immunocompromised and experience a shingles outbreak, speak with your doctor about any concerning symptoms that occur in addition to a rash. Recognizing the symptoms of encephalitis as early as possible can help prevent disease progression and complications.

It’s not always possible to prevent encephalitis. However, you can take steps to help avoid exposure to certain infections that cause the disease:

  • Make sure you and your children keep vaccinations current, including recommended vaccines when traveling.
  • Practice good hygiene by washing your hands frequently with soap and water.
  • Avoid sharing eating utensils.
  • Protect yourself from exposure to mosquitoes and ticks with long-sleeved shirts, long pants, and repellent.
  • Avoid contact with people experiencing a shingles outbreak.

The outlook for a person with VZV encephalitis depends on whether they are immunocompromised and how early they receive a diagnosis and treatment.

Research suggests the death rate for people with VZV encephalitis is 5–15%. In people who are immunocompromised, the likelihood of dying may be up to 80%.

An estimated 40% of people with encephalitis require admission to the intensive care unit (ICU). A 2022 case series study found that 1 in 3 critically ill people with VZV encephalitis had favorable neurological outcomes 1 year after admission to the ICU.

Recovery from encephalitis can be a long and difficult process. Many people do not make a full recovery and have long-term complications due to brain damage.

Complications of encephalitis can include:

  • memory loss
  • frequent seizures
  • personality changes
  • difficulty with concentration and problem-solving
  • persistent fatigue
  • hearing or speech loss
  • blindness

The earlier a person with VZV encephalitis receives treatment, the better the chances of a positive outcome.

In very rare cases, encephalitis may develop along with shingles. This can occur when the virus that causes shingles spreads to the central nervous system.

It’s important to get treatment as early as possible to improve the outlook for encephalitis, which is a serious medical condition.

Speak with a doctor and get immediate medical care if you recognize the signs and symptoms of encephalitis.