Shingles is a rash that causes blisters on the skin, which may feel painful or itchy. Disseminated shingles is a widespread form of shingles that covers more areas of the body.

Shingles, or herpes zoster, is a skin rash that causes blisters across one side of the body. The same virus that causes chickenpox, the varicella-zoster virus, causes shingles.

Disseminated shingles occurs when the rash covers a wider area of the body than localized shingles, in which a rash is contained within a certain area.

This article looks at what disseminated shingles is, who it may affect, symptoms, possible complications, and treatment.

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Disseminated shingles is a complication of shingles where the rash covers a wider area of the body.

A dermatome is an area of skin that a spinal nerve supplies. Spinal nerves, called nerve roots, branch off the spinal cord at different points along the spine.

There are 31 pairs of different spinal nerves. Each dermatome in the body corresponds to a pair of spinal nerves and uses the nerves to communicate with the brain.

According to a 2019 article, shingles usually occurs in one or two dermatomes on the face or chest area and does not spread across the midline of the body.

Shingles appears as a cluster of bumps or fluid-filled blisters. People may have a few lesions outside the main cluster, but if there are more than 20 lesions outside the main rash, this is disseminated shingles.

Disseminated shingles may affect three or more dermatomes.

Learn more about shingles here.

It is possible for anyone who has had chickenpox to get shingles. This is because the virus that causes both conditions remains dormant in nerve cells in the body after people recover from chickenpox.

If the virus activates again, it causes shingles. There is no clear reason why the virus becomes active, but risk factors include older age and having a weakened immune system.

According to the National Institute on Aging, around 50% of shingles cases affect people who are 60 years old or above, and the risk of shingles becomes greater at 70 years or above. If the immune system is less capable of fighting off an infection, it puts people at a higher risk of shingles.

Factors that can weaken the immune system include:

Stress or a cold can also weaken the immune system temporarily.

Disseminated shingles affects around 2% of the general population. It affects people with compromised immune systems in around 15–30% of cases.

Learn about the link between shingles and HIV here.

The varicella-zoster virus causes shingles and chickenpox. The virus can pass easily from a person with chickenpox to someone who has never had chickenpox or has not had a vaccination against chickenpox.

Once people have had chickenpox, the varicella-zoster virus remains dormant in the body. If the virus reactivates, it causes shingles.

It is also possible for people with shingles to pass on the varicella-zoster virus to people who have not previously had chickenpox or the chickenpox vaccine.

The virus can pass on through close contact with a person with shingles, such as direct contact with the blisters or breathing in virus particles from the blisters.

It is not possible to get shingles from a person with shingles. If people come into contact with the infection, it will cause chickenpox. However, they may develop shingles later in life.

Disseminated shingles may appear similar to chickenpox, and it may be difficult to tell the difference between the conditions.

Symptoms of disseminated shingles include:

Shingles usually occurs as a single stripe of blisters around one side of the body or on one side of the face. Disseminated shingles may cover a wider area than this and may cross the midline of the body.

Treatment for disseminated shingles may involve antiviral medications. People with a weakened immune system may require treatment in hospital.

Treatment in a hospital can involve intravenous antiviral medication, such as acyclovir. Doctors may also give people pain relief medication, such as morphine.

If symptoms are improving, people may then switch to taking acyclovir orally and be able to continue their recovery at home.

The Centers for Disease Control and Prevention (CDC) recommends that people have the recombinant zoster vaccine to prevent shingles and any complications.

According to the CDC, two doses of the vaccine Shingrix offers over 90% protection against herpes zoster and postherpetic neuralgia (PHN), which is long lasting, persistent pain following shingles. People will have around 85% or more protection for a least 4 years following vaccination.

Learn more about the Shingrix vaccine for shingles and chickenpox.

The most common complication of disseminated shingles is PHN. PHN is persistent pain in the area where a shingles rash was that continues for over 90 days after the rash appeared.

Disseminated shingles may also cause a nerve disorder called plexopathy, which can cause weakness in the limbs.

Other possible complications can affect the liver, lungs, or brain and may cause encephalitis or pneumonitis.

Learn more about some aftereffects of shingles.

People need to contact a doctor right away if they think they have shingles or disseminated shingles, particularly if they have a weakened immune system.

Antiviral medications to treat shingles are most effective when people take them as soon as possible after the rash first appears.

Disseminated shingles is rare and most often affects people with severely compromised immune systems.

Prompt treatment is essential in managing the condition and preventing serious complications such as encephalitis or pneumonitis.

A person’s outlook may depend on their age, the status of their immune system, the severity of their symptoms, and other health conditions.

Early diagnosis and treatment along with high quality care may help provide good outcomes for people with disseminated shingles.

Shingles is a painful, itchy rash that causes blisters to form on one side of the body or face. Disseminated shingles covers a wider area and may cross the midline of the body.

Disseminated shingles is rare but can be more serious than localized shingles. Older adults and people with a weakened immune system may be at higher risk of developing disseminated shingles.

Prompt treatment with antiviral medication can help treat disseminated shingles and prevent complications.