Herpes Zoster (Shingles)

Herpes zoster, commonly known as shingles, is a painful viral infection that causes a distinctive blistering rash on one side of the body. Anyone who has had chickenpox is at risk, as the same virus remains dormant in the body and can reactivate years later, especially as we age.

Table of contents

• What is herpes zoster
• What causes herpes zoster
• Who is at risk for herpes zoster
• Symptoms and stages of herpes zoster
• How herpes zoster spreads
• Complications of herpes zoster
• How doctors diagnose herpes zoster
• Treatment options
• Prevention and vaccination

What is herpes zoster

Herpes zoster, also called shingles, is a viral infection that causes a painful rash and nerve damage^[1]. It is caused by the reactivation of the varicella-zoster virus (VZV), which is the same virus that causes chickenpox^[2]. After a person recovers from chickenpox, the virus does not leave the body completely. Instead, it remains inactive (dormant) in nerve cells in the spine for years before it can reactivate and cause herpes zoster^[3].

The infection is characterized by a painful, blistering rash that typically appears on one side of the body, often as a single stripe of blisters^[4]. An estimated one million people get shingles each year in the United States^[2]. About 1 in every 3 people will develop herpes zoster in their lifetime^[2].

What causes herpes zoster

Herpes zoster occurs when the varicella-zoster virus, which has been dormant in the sensory ganglia (nerve clusters) after a previous chickenpox infection, becomes active again^[5]. When the virus reactivates, it replicates in neuronal cell bodies, and virus particles shed from the cells are carried down the nerve to the area of skin supplied by that nerve^[3]. In the skin, the virus causes local inflammation and blistering^[3].

Experts are not always certain why the virus reactivates, but it tends to happen as people get older and their immune system naturally starts to weaken^[1]. Several triggering factors have been recognized, including emotional stress, use of immunosuppressant medications, acute or chronic illness, exposure to the virus, presence of a cancer, pressure on nerve roots, spinal surgery, or a serious injury^[3].

Who is at risk for herpes zoster

Anyone who has had chickenpox can develop shingles^[2]. More than 99% of Americans born before 1980 had chickenpox, even if they don’t remember it^[2]. While children can have shingles, it is not common. The condition is much more frequent in adults, especially older people^[4].

The risk of herpes zoster increases sharply with advancing age, roughly doubling in each decade past the age of 50 years^[3]. People over the age of 50 account for a significant proportion of cases^[5]. The incidence ranges from 1.2 to 3.4 per 1,000 persons per year among younger healthy individuals, while it is 3.9 to 11.8 per 1,000 persons per year among patients older than 65 years^[3].

Your risk of shingles and serious complications increases if you have a weakened immune system. This includes people with medical conditions that affect immune function, such as certain cancers like leukemia and lymphoma, HIV infection, or those who take drugs that suppress the immune system, like steroids and medicines given after an organ transplant^[2]. People with cancer have a 40% increased risk of developing herpes zoster^[5]. Those suffering from chronic diseases such as diabetes, autoimmune diseases, heart disease, or kidney disease are also at increased risk^[5].

Most people who develop shingles only have it one time during their life, though it can recur^[2]. About 1% of people get a second episode^[5]. Recurrences are most common in patients who are immunosuppressed^[3].

Symptoms and stages of herpes zoster

The symptoms of herpes zoster can be divided into three distinct phases^[5]:

Preeruptive phase (preherpetic neuralgia stage)

This is the earliest stage, which usually lasts 1 to 3 days, though it can extend up to 10 days^[5]. During this phase, there are no visible skin changes. Early signs include burning or shooting pain, tingling, itching, or numbness, usually on one side of the body^[1]. The pain can be intense and is typically confined to the area where the rash will later appear^[6].

Other symptoms that can appear during this phase include areas of reddish or discolored skin, fever, chills, headache, generally feeling unwell (a condition called malaise), and stomach upset^[1]. Some people may experience fatigue, diarrhea, or light sensitivity^[5].

Acute eruptive phase

The acute eruptive phase begins when a painful, raised or blistered rash appears, typically 1 to 3 days after the onset of pain^[1]. The rash starts as a crop of red bumps (papules) on patchy, reddened skin. These quickly develop into grouped fluid-filled blisters (vesicles) on an inflamed base^[5]. New lesions continue to appear for several days, each blistering or becoming pustular then crusting over^[3].

The rash most commonly appears on one side of the body around the waist, or on one side of the face, neck, chest, belly, or back^[1]. It typically looks like a single stripe of blisters that wraps around either the left or right side of the torso^[6]. The characteristic pattern follows a dermatome, which is an area of skin supplied by a single nerve, and it stops abruptly at the midline of the body^[1].

The chest (thoracic), neck (cervical), forehead (ophthalmic), and lumbar/sacral regions are most commonly affected at all ages^[5]. Herpes zoster occasionally causes blisters inside the mouth or ears, and can also affect the genital area^[1]. The blisters initially are clear but eventually cloud, rupture, crust, and begin to heal^[5]. Within about 10 days, the blisters dry out and crust over into scabs, which may take a few weeks to completely go away^[1].

In uncomplicated cases, recovery is complete within 2 to 3 weeks in children and young adults, and within 3 to 4 weeks in older patients^[3]. Almost all adults experience pain, typically severe^[5]. Some people experience shingles pain without ever developing the rash, a condition known as herpes zoster sine eruptione^[1].

Chronic phase (postherpetic neuralgia)

This phase is characterized by persistent or recurring pain lasting 30 or more days after the acute infection or after all lesions have crusted^[8]. Pain usually is confined to the area of the original rash and can last for months or years^[1].

How herpes zoster spreads

Shingles itself is not contagious—you cannot get shingles from someone who has shingles^[2]. However, you can get chickenpox from someone with shingles if you have never had chickenpox or never received the chickenpox vaccine^[2]. The varicella-zoster virus can spread through direct contact with fluid from shingles rash blisters or from breathing in virus particles that come from the blisters^[2].

People with active herpes zoster lesions can spread the virus until their blisters dry and scab over^[2]. They cannot spread the virus before the blisters appear or after the rash scabs over^[2]. The risk of spreading the virus is low if the shingles rash is kept covered^[7].

To prevent spreading the virus to others, people with shingles should cover the rash, avoid touching or scratching it, wash their hands often for at least 20 seconds, and avoid contact with pregnant women who never had chickenpox or the chickenpox vaccine, premature or low birth weight infants, and people with weakened immune systems until the rash scabs over^[2].

Complications of herpes zoster

The most common complication of shingles is nerve pain that doesn’t go away when the rash heals, called postherpetic neuralgia (PHN)^[1]. This can last for months or years and can be extremely painful, interfering with daily life^[1]. About 20% of patients with herpes zoster develop postherpetic neuralgia, with the most established risk factor being age—this complication occurs nearly 15 times more often in patients more than 50 years old^[11]. Between 9% and 45% of all herpes zoster cases result in PHN^[8].

Other complications include^[1]:

• Bacterial infection of the blisters
• Vision loss from an eye infection when the ophthalmic division of the nerve is involved
• Facial paralysis, or Ramsay Hunt syndrome, which occurs when the facial nerve is affected
• Hearing loss, tinnitus (ringing in the ears), and other hearing issues
• Brain inflammation (encephalitis)
• Vertigo (dizziness)
• Pneumonia
• Infection of internal organs, including the gastrointestinal tract and lungs

Muscle weakness occurs in about one in 20 patients^[5]. Deep blisters can take weeks to heal and may result in scarring^[5]. Rarely, shingles is fatal^[1]. About 96 deaths occur each year in the United States from herpes zoster complications^[14].

How doctors diagnose herpes zoster

Healthcare providers usually diagnose shingles by taking your medical history and looking at the rash^[1]. If the rash follows the line of dermatomes (areas of skin along a nerve) and doesn’t cross the midline of your body, that’s a clue that it’s shingles^[1]. The classic physical finding includes painful grouped blisters resembling herpes on a reddened base^[8].

In some cases, your provider may scrape off tissue from the rash or swab some fluid from the blisters and send the sample to a laboratory for testing^[1]. This helps confirm if your rash is caused by shingles and can identify the specific virus^[7].

Treatment options

There is no cure for shingles. Episodes of herpes zoster generally are self-limited and resolve without intervention, though they tend to be more severe in adults than in children^[10]. However, early treatment can reduce the extent and duration of symptoms and possibly the risk for chronic complications like postherpetic neuralgia^[10].

Antiviral medications

Healthcare providers usually treat shingles with orally administered antiviral drugs, which are most effective when started within 72 hours after the onset of the rash^[1]. These medications may speed healing, lower the risk of complications, and help make the attack shorter and less severe^[7]. They may also help prevent postherpetic neuralgia^[7].

Common antiviral medications include acyclovir, famciclovir, and valacyclovir^[1]. Some studies have shown that famciclovir and valacyclovir can shorten the duration of postherpetic neuralgia^[13]. Oral antiviral medication also reduces the risk of eye complications in patients with ophthalmic herpes zoster^[13].

Pain management

Shingles can cause severe pain, so healthcare providers may prescribe pain relievers to help with discomfort^[7]. Conservative therapy includes nonsteroidal anti-inflammatory drugs (NSAIDs)^[10]. For more severe pain, especially in cases of postherpetic neuralgia, patients may require narcotics for adequate pain control^[11].

Other medications used for nerve pain include^[11]:

• Tricyclic antidepressants, such as amitriptyline, often given in low doses
• Anticonvulsants, such as gabapentin
• Capsaicin cream or patches, applied topically
• Lidocaine patches or cream for numbing

Corticosteroids

The addition of an orally administered corticosteroid can provide modest benefits in reducing the pain of herpes zoster and the incidence of postherpetic neuralgia^[11]. Corticosteroids help alleviate acute pain^[13].

Supportive care

To help relieve symptoms at home, cool washcloths, calamine lotion, and oatmeal baths may help relieve some of the itching^[7]. Wet dressings with 5% aluminum acetate (Burow solution), applied for 30 to 60 minutes 4 to 6 times daily, can also be helpful^[10].

Treatment is of greatest benefit in those patient populations at risk for prolonged or severe symptoms, specifically immunocompromised people and persons older than 50 years^[10]. If you think you might have shingles, contact your provider as soon as possible, ideally within 3 days after the rash appears^[7].

Prevention and vaccination

The best way to prevent shingles is vaccination^[2]. A safe and effective vaccine is available to prevent shingles and its complications^[4]. The Centers for Disease Control and Prevention recommends 2 doses of recombinant zoster vaccine (called Shingrix) to prevent shingles and related complications in adults 50 years and older^[2]. Shingrix is also recommended for adults 19 years and older who have weakened immune systems because of disease or therapy^[2].

Vaccination helps protect against shingles by maintaining high levels of immunity. It is believed that herpes zoster occurs due to the failure of the immune defense system to control the latent replication of the virus^[3]. Individuals who maintain a high level of immunity rarely develop shingles^[3].