Chickenpox (varicella) rarely causes complications, but it is not always harmless. It can cause hospitalization and, in rare cases, death. The major long-term complication of varicella is the later reactivation of the herpes zoster virus and the development of shingles.
Certain factors put people at higher risk for complications of the varicella-zoster virus:
- Any adult who gets chickenpox is at increased risk for complications.
- People with impaired immune systems due to diseases (such as Hodgkin disease) or cancer treatments (chemotherapy, bone marrow, or stem cell transplants) are at higher risk for chickenpox complications. They also have increased risk for herpes zoster and its complications.
- Pregnant women who get chickenpox have an increased risk for life-threatening pneumonia. Infection during the first trimester or early second trimester may also affect the developing fetus and potentially cause birth defects. If the mother contracts chickenpox during the days following birth, her newborn is at risk for developing a serious varicella infection. Shingles is extremely rare in pregnant women.
Specific Complications of Chickenpox (Varicella)
Aside from itching, the complications described below are usually rare.
Intense itching is the most common complication of chickenpox. It can be very distressing, particularly for small children. Many home remedies can help relieve the discomfort. It is important not to scratch the scabs because this can lead to scarring. [See: Treatment for Chickenpox section in this report.]
Bacterial Skin Infections
In some cases, a secondary bacterial infection may develop at sites that were scratched. If the skin around the scab becomes red, swollen, or warm, this may be a sign of a secondary bacterial infection. If you or your child develops these symptoms contact your health care provider because in rare cases, serious bacterial complications can occur.
Varicella pneumonia is an uncommon but serious complication of chickenpox. It usually develops 1 to 6 days after the chickenpox rash appears. Fever and cough may be signs of varicella pneumonia. Pregnant women, people who are immunocompromised, and smokers are at increased risk for this lung complication.
Encephalitis and Meningitis
Encephalitis and meningitis are rare but serious neurological (nervous system) complications of chickenpox. Meningitis is inflammation of the lining of the spinal cord and brain. Encephalitis is the inflammation of the brain itself. Signs and symptoms include:
- Sudden fever
- Stiff neck
- Nausea and vomiting
- Sensitivity to light
In encephalitis, seizures and coma can occur. Meningitis and encephalitis are very serious conditions that require immediate medical treatment.
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. Children should never take aspirin when they have a viral infection or fever. Acetaminophen (Tylenol, generic) is often given instead for fever or pain in children.
Disseminated varicella, which develops when the virus spreads to organs in the body, is extremely serious especially for people with weakened immune systems.
Specific Complications of Shingles (Herpes Zoster)
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 usually affects people with herpes zoster who are over 60 years old. The older a person is the longer PHN is likely to last. It rarely occurs in people under age 40.
- 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. People whose eyes have been affected also have increased risk for PHN.
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 is associated with Stevens-Johnson syndrome, an extensive and serious condition in which widespread blisters cover mucous membranes and large areas of the body.
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. People with HIV/AIDS may be at particular risk for a chronic infection in the cornea of the eye.
Herpes zoster can also cause a severe infection in the retina called acute retinal necrosis syndrome. In such cases, visual loss can develop. Although this complication usually follows a herpes outbreak in the face, it can occur after an outbreak in any part of the body.
Shingles can increase the risk for specific neurological complications:
- Guillain-Barré Syndrome. Guillain-Barré syndrome is caused by the inflammation of the nerves and is 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, including breathing. Symptoms vary from mild to severe enough to require hospitalization. The disorder typically 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. Severe or partial hearing loss may occur but this too is usually temporary. Facial paralysis, on the other hand, may be permanent.
- Bell Palsy. Bell palsy is a partial paralysis of the face often caused by damage to a facial nerve. Sometimes, it is difficult to distinguish between Bell palsy and Ramsay Hunt syndrome, particularly in the early stages. In general, Ramsay Hunt syndrome tends to be more severe than Bell palsy.
- Meningitis and Encephalitis. Inflammation of the membrane around the brain (meningitis) or in the brain itself (encephalitis) is an uncommon complication in people with herpes zoster. The encephalitis is generally mild and resolves in a short period. In rare cases, particularly in people with impaired immune systems, it can be severe and even life threatening.
- Vascular Complications. Some research suggests that herpes zoster may increase the risk for transient ischemia attack (TIA), stroke, or possibly heart attack in the first weeks or months following a shingles outbreak. Antiviral drugs may be protective.
Disseminated Herpes Zoster
As with disseminated chickenpox, disseminated herpes zoster, which can spread 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.