Chickenpox (varicella) rarely causes complications, but it is not always harmless. It can cause hospitalization and, in rare cases, death. Fortunately, since the introduction of the vaccine in 1995, hospitalizations have declined by nearly 90%, and there have been few fatal cases of chickenpox.
Older adults have the greatest risk for dying from chickenpox, with infants having the next highest risk. Males (both boys and men) have a higher risk for a severe case of chickenpox than females. Children who catch chickenpox from family members are more likely to have a severe case than if they caught it outside the home. The older the child, the higher the risk for a more severe case. But even in such circumstances, chickenpox is rarely serious in children.
Other factors put individuals at specifically higher risk for complications of the varicella-zoster virus. Patients with diseases, such as Hodgkin's disease, who receive bone marrow or stem cell transplants are at higher risk for herpes zoster and its complications.
Although a pregnant woman has a very low risk for contracting chickenpox, if she does become infected the virus increases her risk for life-threatening pneumonia. Infection in the pregnant woman in the first trimester also poses a 1 - 2% chance for infecting the developing fetus and potentially causing birth defects. Herpes zoster is extremely rare in pregnant women, and there is almost no risk for the unborn child in such cases. The major long-term complication of varicella is the later reactivation of the herpes zoster virus and the development of shingles. Shingles occurs in about 20% of people who have had chickenpox.
Specific Complications of Chickenpox (Varicella)
Aside from itching, the complications described below are very rare.
Itching. Itching, the most common complication of the varicella infection, can be very distressing, particularly for small children. Certain home remedies are available that can alleviate the discomfort. [See: "Treatment for Chickenpox" section below.]
Secondary Skin Infections and Scarring. Small scars may remain after the scabs have fallen off, but they usually clear up within a few months. In some cases, a secondary infection may develop at sites which the patient has scratched. The infection is usually caused by the bacteria Staphylococcus aureus or Streptococcus pyogenes. Permanent scarring may occur as a result. Children with chickenpox are at much higher risk for this complication than adults are, possibly because they are more likely to scratch.
Bacterial superinfection of the skin caused by group A streptococcus is the most common serious complication of chickenpox (but it is still rare). The infection is usually mild, but if it spreads in deep muscle, fat, or in the blood, it can be life threatening. Infection can cause serious conditions, such as necrotizing fasciitis (the so-called flesh-eating bacteria) and toxic shock syndrome (TSS). Symptoms include:
- A persistent or recurrent high fever
- Redness, pain, and swelling in the skin and the tissue beneath
Ear Infections. Some children experience ear infections from chickenpox. Hearing loss is a very rare result of this complication.
A middle ear infection is also known as otitis media. It is one of the most common of childhood infections. With this illness, the middle ear becomes red, swollen, and inflamed because of bacteria trapped in the eustachian tube.
Pneumonia. Pneumonia is suspected if coughing and abnormally rapid breathing develop in patients who have chickenpox. Adults and adolescents with chickenpox are at some risk for serious pneumonia. Pregnant women, smokers, and those with serious medical conditions are at higher risk for pneumonia if they have chickenpox. Oxygen and intravenous acyclovir are key treatments for this condition. Pneumonia that is caused by varicella can result in lung scarring, which may impair oxygen exchange over the following weeks, or even months.Click the icon to see an image of pneumonia.
- Inflammation in the Brain. Encephalitis and meningitis, infection or inflammation in the central nervous systems, can occur in rare cases in both children and adults. This condition can be very dangerous, causing coma and even death.
- Stroke. Although stroke in children is extremely rare, a condition called cerebral vasculitis, in which blood vessels in the brain become inflamed, has been associated with varicella-zoster. Varicella may be a factor in some cases of stroke in young adults.
Reye Syndrome. Reye syndrome, a disorder that causes sudden and dangerous liver and brain damage, is a side effect of aspirin therapy in children who have chickenpox or influenza. The disease can lead to coma and is life threatening. Symptoms include rash, vomiting, and confusion beginning about a week after the onset of the disease. Because of the strong warnings against children taking aspirin, this condition is, fortunately, very rare. Children should never be given aspirin when they have a viral infection or fever. Acetaminophen (Tylenol) is the preferred drug for fever or pain in patients younger than age 18 years.
Disseminated Varicella. Disseminated varicella, which develops when the virus spreads to organs in the body, is extremely serious and is a major problem for patients with compromised immune systems.
Specific Complications of Shingles (Herpes Zoster)
Postherpetic Neuralgia. Postherpetic neuralgia (PHN) is pain that persists for longer than a month after the onset of herpes zoster. It is the most common severe complication of shingles. Risk factors for PHN include:
- Age. PHN affects about 25% of herpes zoster patients over 60 years old. The older a person is, the longer PHN is likely to last. It rarely occurs in people under age 50.
- Gender. Some studies suggest that women may be at slightly higher risk for PHN than men.
- Severe or complicated shingles. People who had prodromal symptoms or a severe attack (numerous blisters and severe pain) during the initial shingles episode are also at high risk for PHN. The rate is also higher in people whose eyes have been affected by zoster.
In most cases, PHN resolves within 3 months. Studies report that only about 10% of patients experience pain after a year. Unfortunately, when PHN is severe and treatments have not been very effective, the persistent pain and abnormal sensations can be profoundly frustrating and depressing for patients.
Skin Infections. If the blistered area is not kept clean and free from irritation, it may become infected with group A Streptococcus or Staphylococcus bacteria. If the infection is severe, scarring can occur.
In very rare cases, herpes zoster has been associated with Stevens-Johnson syndrome, an extensive and serious condition in which widespread blisters cover mucous membranes and large areas of the body.
Eye Infections. If shingles occurs in the face, the eyes are at risk, particularly if the path of the infection follows the side of the nose. If the eyes become involved (herpes zoster ophthalmicus), a severe infection can occur that is difficult to treat and can threaten vision. AIDS patients may be at particular risk for a chronic infection in the cornea of the eye.Click the icon to see an image of the eye.
Herpes zoster can also cause a severe infection in the retina called imminent acute retinal necrosis syndrome. In such cases, visual loss develops within weeks or months after the herpes zoster outbreak has resolved. Although this complication usually follows a herpes outbreak in the face, it can occur after an outbreak in any part of the body.
- Guillain-Barre Syndrome. Guillain-Barre syndrome is caused by inflammation of the nerves and has been associated with a number of viruses, including herpes zoster. The arms and legs become weak, painful, and, sometimes, even paralyzed. The trunk and face may be affected. Symptoms vary from mild to severe enough to require hospitalization. The disorder resolves in a few weeks to months. Other herpes viruses (cytomegalovirus and Epstein-Barr), or bacteria (Campylobacter) may have a stronger association with this syndrome than herpes zoster.
- Ramsay Hunt Syndrome. Ramsay Hunt syndrome occurs when herpes zoster causes facial paralysis and rash on the ear (herpes zoster oticus) or in the mouth. Symptoms include severe ear pain and hearing loss, ringing in the ear, loss of taste, nausea, vomiting, and dizziness. Ramsay Hunt syndrome may also cause a mild inflammation in the brain. The dizziness may last for a few days, or even weeks, but usually resolves. Severity of hearing loss varies from partial to total; however, this too usually goes away. Facial paralysis, on the other hand, may be permanent.
- Bell's Palsy. Bell's palsy is partial paralysis of the face. Sometimes, it is difficult to distinguish between Bell's palsy and Ramsay Hunt syndrome, particularly in the early stages. In general, Ramsay Hunt syndrome tends to be more severe than Bell's palsy.
- Meningitis and Encephalitis. Inflammation of the membrane around the brain (meningitis) or in the brain itself (encephalitis) is a rare complication in people with herpes zoster. The encephalitis is generally mild and resolves in a short period. In rare cases, particularly in patients with impaired immune systems, it can be severe and even life threatening.
- Stroke. Some research suggests that herpes zoster increases the risk for stroke in the year following a shingles outbreak.
Disseminated Herpes Zoster. As with disseminated chickenpox, disseminated herpes zoster, which spreads to other organs, can be serious to life-threatening, particularly if it affects the lungs. People with compromised immune systems are at greatest danger. It is very rare in people with healthy immune systems.