Human Herpesvirus 6 (HHV-6) Links to Numerous Diseases

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Human herpesvirus 6, also called HHV-6, is most likely in your body right now, hanging out and not doing much of anything. If you're part of a certain minority, though, it may be causing one or more illnesses.

doctor taking patient information
Pornpak Khunatorn / Getty Images 

As the name suggests, HHV-6 was the sixth member of the herpes virus "family" to be discovered. Other herpes viruses include the Epstein-Barr virus, cytomegalovirus, and herpes simplex 1 and 2 (both of which can cause cold sores and genital herpes).

Symptoms are most likely when you first become infected; however, it is possible for the virus to reactivate at some point down the road. In that case, it may cause health problems including any of several neurological conditions.

HHV-6 can target the nervous system, which is made up of your brain and spinal column, the immune system, and a wide variety of organs.

HHV-6 comes in two types, called A and B. Scientists originally thought they were variants of the same virus, but now they believe them to be completely separate from each other.

HHV-6 A is less common and may be acquired in adulthood, while the B type generally is acquired in early childhood and is found in the vast majority of the population.

All herpes-family viruses stay in your body for life, usually lying in a dormant (inactive) state. You cannot cure HHV-6, but it does not cause disease in everyone.


Research links HHV-6 A to numerous neurological conditions. Some of these links are supported by considerable evidence, while other ties are less certain. At this point, we can't say for certain that HHV-6 directly causes any of these conditions.

Diseases linked to HHV-6 reactivation are many. For most of them, though, we don't know if HHV-6 is the actual cause.

Some of the diseases are autoimmune, including:

Others are types of cancer or cancer related, such as:

More conditions linked to HHV-6 A reactivations include:

Some people with an active HHV-6 infection may develop more than one of these illnesses. However, a vast majority of people infected with this virus have no symptoms at all, and many have only mild short-term symptoms.

Anyone with HHV-6 can experience a reactivation, but it is most common in people with a compromised immune system, such as organ transplant recipients and people with HIV.


HHV-6 B is the more common form of the virus. Most people—more than 90%—are infected during their first three years and carry it around for the vast majority of life. For most babies, the initial infection doesn't cause any noticeable health problems.


In about 20% of children, however, HHV-6 B infection causes a condition called roseola. Symptoms of roseola generally come in two stages. The first may include:

  • Sudden high fever (above 103 F) lasting three to five days
  • Mild sore throat
  • Runny nose
  • Cough
  • Swollen lymph nodes in the neck
  • Irritability
  • Mild diarrhea
  • Decreased appetite
  • Swollen eyelids

Within a day of the fever going away, the child may develop a rash that doesn't itch or cause discomfort.

The rash is made up of lots of small pink spots or patches, sometimes inside a white ring. It usually begins on the torso and spreads to the limbs and possibly the face. It can go away in as little as a few hours or hang around for several days.

Roseola usually isn't serious. In rare cases, a child may develop a high fever that can lead to complications such as seizures. Treatment is typically focused on alleviating fever and ensuring plenty of bed rest.


In addition to fever-induced seizures, HHV-6 B has been linked to epilepsy, a chronic neurological condition characterized by recurrent seizures.

Symptoms of epilepsy can vary and may involve any of the processes coordinated by the brain. Epilepsy is chronic, meaning that it requires long-term treatment and management.

Common symptoms of epilepsy include:

  • Uncontrollable jerking movements
  • Temporary confusion
  • Staring off into space for a short time
  • Fear and anxiety
  • A sense of deja vu
  • Loss of consciousness
  • Loss of awareness


HHV-6 is also linked to encephalitis (inflammation of the brain), a condition that can be fatal. Common symptoms of encephalitis include:

  • Seizures
  • Headaches
  • Muscle or joint pain
  • Fatigue
  • Weakness
  • Fever
  • Confusion
  • Partial paralysis
  • Speech problems
  • Hearing problems
  • Loss of consciousness

In babies and young children, it may also cause:

  • Bulging in the skull's soft spots
  • Nausea
  • Vomiting
  • Stiffness
  • Irritability
  • Poor feeding
  • Sleeping through feeding times

If you suspect a child has encephalitis, it is imperative that you seek immediate medical attention.

According to research in Infectious Disease Clinics of North America, nearly all children with encephalitis in the United States require hospitalization with 40% requiring critical care in an intensive care unit.


A few different blood tests can detect whether you're infected with HHV-6. One of the tests comes back with a "yes" or "no" answer, which isn't terribly useful since you've probably carried this virus since childhood.

A better test looks at the level of antibodies in your blood, since an elevated number can indicate an active infection. (Your body produces antibodies in response to infection, with each type "tailored" to identify and tag a specific infectious microorganism.)

Complicating matters is the fact that a negative test result doesn't necessarily mean you don't have an active infection. That's because HHV-6 can infect a single organ, such as the brain, heart, lungs, liver, or uterus. To detect that, the specific tissues must be tested.

Because blood tests are often unreliable, your healthcare provider may diagnose HHV-6 based on symptoms alone, ruling out other likely causes such as mononucleosis, meningitis, cytomegalovirus (CMV), rubella, or sepsis.

Your healthcare provider may also use diagnostic imaging, tissue biopsy, lumbar puncture ("spinal tap"), or bronchoscopy (to view inside your airways).

Before diagnosing roseola in a baby, healthcare providers generally consider other possible causes of rash and fever—of which there are many. Different lab tests are used for diagnosing HHV-6 reactivation in organ transplant recipients or people with hepatitis, encephalitis, or HIV.


At this point, we don't have a well-established treatment regimen for active HHV-6 infection. Because symptoms can vary widely from one person to another, healthcare providers generally tailor the treatment to the individual case.

Antiviral drugs have gotten some attention for treating HHV-6, but so far, they remain unproven. Some of the more common drugs suggested for combating this virus are Cytovene (ganciclovir) and Foscavir (foscarnet).

There's no vaccine to prevent HHV-6 infection.

A Word From Verywell

If you think you may have an illness that could be related to an HHV-6 infection or reactivation, be sure to bring it up with your healthcare provider. A proper diagnosis is the first step toward finding the treatments that help you feel better.

Many of the illnesses linked to HHV-6 are chronic, so you may have to learn to manage them. Educating yourself, working with your healthcare provider, and exploring different treatment options are all important when it comes to finding your optimum treatment regimen.

Frequently Asked Questions

  • How do you get Herpesvirus 6?

    Similar to a cold, human herpesvirus 6 is often passed on when mucus or respiratory particles from an infected person are picked up by another person. Thorough hand washing is the best way to prevent spreading it.

  • What are the symptoms of an HHV-6 infection?

    The HHV-6B infection, which is most often acquired in early childhood, can cause fever, diarrhea, and, possibly, a roseola rash. In rare instances, it can also lead to encephalitis or seizures. HHV-6A may not present with any symptoms when it’s first contracted. 

  • Can pregnant women pass HHV-6 on to their babies?

    Yes. It's possible that HHV-6 could be passed on to a baby during birth since the virus’s DNA might be shed in a woman’s genital tract. It’s estimated this happens in 1% to 2% of pregnancies.

10 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.
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  2. Agut H, Bonnafous P, Gautheret-dejean A. Laboratory and clinical aspects of human herpesvirus 6 infections. Clin Microbiol Rev. 2015;28(2):313-335. doi:10.1128/CMR.00122-14

  3. Mullins TB, Krishnamurthy K. Roseola infantum (exanthema subitum, sixth disease). StatPearls.

  4. Cleveland Clinic. Roseola infantum/sixth disease.

  5. American Academy of Family Physicians. Epilepsy.

  6. Messacar K, Fischer M, Dominguez SR, et al. Encephalitis in US children. Infect Dis Clin North Am. 2018;32(1):145-162. doi:10.1016/j.idc.2017.10.007

  7. Komaroff AL, Zerr DM, Flamand L. Summary of the 11th International Conference on Human Herpesviruses-6A, -6B, and -7J Med Virol. 2020;92(1):4–10. doi:10.1002/jmv.25576

  8. American Academy of Pediatrics. Human Herpes Virus 6.

  9. HHV-6 Foundations. What Is HHV-6?

  10. Komaroff AL, Rizzo R, Ecker JL. Human herpesviruses 6a and 6b in reproductive diseases. Front Immunol. 2021;12:648945. doi:10.3389/fimmu.2021.648945

Additional Reading

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.