What is postherpetic neuralgia (PHN)?
Postherpetic neuralgia (PHN) is a complication of shingles infection (also called herpes zoster). Shingles is caused by the reactivation of the varicella-zoster virus, which is the same virus that causes chickenpox.
Shingles causes a painful, blistering rash and other symptoms. The rash most commonly occurs in a band pattern on one side of your body, usually on your trunk (central core of your body). The rash turns into blisters. As the rash/blisters go away, pain may remain. When pain remains, the condition is called postherpetic neuralgia.
What does postherpetic neuralgia (PHN) feel like?
You will feel pain in the area where the shingles rash developed. The pain can be constant or “come and go.” Some people describe the pain as burning, jabbing or aching. Others (less common) say the affected area feels numb or itchy.
How long does postherpetic neuralgia (PHN) last?
Postherpetic neuralgia (PHN) can last for weeks, months, or in some people, years after the shingles rash goes away. In most people, shingles pain goes away in one to three months. However, in one in five people, pain lasts more than one year.
The pain from PHN can be so severe in some people that it disrupts their life. Researchers don’t know why some people have severe or long-lasting pain and others do not.
How common is postherpetic neuralgia (PHN)?
Varicella-zoster virus causes both chickenpox and shingles. About 99% of Americans over age 40 have had chickenpox. About one in three people in the U.S. develop shingles in their lifetime. Some 10 to 18% of people who get shingles will develop postherpetic neuralgia. Postherpetic neuralgia is the most common complication of shingles.
Who is at risk of getting postherpetic neuralgia (PHN)?
Factors that increase the risk of developing postherpetic neuralgia (PHN) include:
- Older age: The chance of developing postherpetic neuralgia increases with age. If you’re older and develop shingles, you’re more likely to develop PHN and have longer lasting and more severe pain than a younger person with shingles. About 10 to 13% of people over age 50 who have had shingles will get PHN. People under age 40 rarely get PHN.
- Weakened immune system: Your immune system weakens as you get older, which allows the inactive varicella-zoster virus to become active again and cause shingles in some people. Medical conditions that can weaken your immune system include cancer, chronic infectious diseases (like HIV/AIDS), being an organ transplant recipient or taking medications that weaken your immune system (such as chemotherapy, immunosuppressant medicines, steroids or anti-organ rejection medicines).
- Severity of your shingles: If you have a severe rash, you have a greater chance of PHN.
- Painful, itchy or tingly feeling before shingles rash: If you had these symptoms in an area of skin a few days before your shingles rash broke out, you are at higher risk of PHN.
- Waiting to see your healthcare provider after shingles rash: If you wait longer than three days after your rash appeared — missing the window to receive antiviral drugs — you have an increased chance of PHN.
Symptoms and Causes
What causes postherpetic neuralgia (PHN)?
Postherpetic neuralgia (PHN) results from damage to nerve fibers during shingles infection. The nerve fibers at the skin in the affected area send exaggerated pain signals to your brain. Postherpetic neuralgia means nerve pain after herpes. Shingles is also called herpes zoster.
Shingles is caused by the varicella-zoster virus, the virus that causes chickenpox. Once you’ve had chickenpox, the virus remains in your body for your entire life, but is dormant or “silent” for years. When the virus becomes reactivated, it causes shingles. A certain percentage of people (< 20%) who get shingles develop PHN.
What are the symptoms of postherpetic neuralgia (PHN)?
Common postherpetic neuralgia symptoms include:
- Burning, sharp, jagging or aching pain in the area where the shingles rash appeared.
- Itchiness or numbness at or near the area of the former rash.
- Pain that is constant or “comes and goes.” Pain typically lasts, on average, for three months after the rash has healed, but can last for more than a year or longer.
- Pain at affected skin area can be brought on even with a light touch (even clothing brushing against skin).
- Pain gets worse at night or in heat or cold temperatures.
Diagnosis and Tests
How is postherpetic neuralgia diagnosed (PHN)?
Postherpetic neuralgia (PHN) is usually diagnosed based on your symptoms, history of having shingles and physical exam. If you’ve had a recent case of shingles and have pain in the area where the shingles rash once was, you likely have PHN. Your provider may want to make sure your pain is not caused by something else, but in most cases, no other tests are needed.
What are the complications of postherpetic neuralgia?
Postherpetic neuralgia can cause:
- Trouble sleeping (insomnia).
- Decreased appetite.
- Poor concentration.
Pain from long-lasting PHN can lead to depression.
Management and Treatment
How is postherpetic neuralgia (PHN) treated?
If shingles is caught within the first three days of its outbreak, your healthcare provider may prescribe the antiviral medication acyclovir (Zovirax®), valacyclovir (Valtrex®) or famciclovir (Famvir®). These medications help the rash/blisters heal faster, keep new sores from forming, decrease pain and itching and reduce length of pain after sores have healed.
If your shingles outbreak is not caught early, your healthcare providers has many options to manage your postherpetic neuralgia (PHN) symptoms.
If your pain is mild, your healthcare provider may recommend:
- Acetaminophen (Tylenol®) or NSAIDs such as ibuprofen (Advil®, Motrin®).
- Creams and patches include lidocaine (Lidoderm®) and capsaicin (Zostrix®).
If your pain is more severe, your healthcare may prescribe:
- Antiseizure drugs gabapentin (Neurontin®, Gralise®) and pregabalin (Lyrica®).
- Antidepressants, such as escitalopram (Lexapro®), quetiapine (Seroquel®) or amitriptyline.
- Botulinum toxin (Botox®) injections in the area where you are having pain.
There’s no clear-cut superior treatment for PHN. Your provider may need to try more than one medication or prescribe the use of several medications at the same time. You and your provider will discuss options and what makes sense to try for you. Contact your provider if your pain is not lessening after taking your medicine. Take all your medications exactly as prescribed.
Can postherpetic neuralgia (PHN) be cured?
Although there is no cure for PHN, it can be treated. For most people with PHN, pain improves with time and eventually goes away. For most people, the pain goes away in one to three months.
Can postherpetic neuralgia be prevented?
The Food and Drug Administration has approved a shingles vaccine, which can reduce your chance of getting shingles and PHN. The recombinant herpes-zoster vaccine (Shingrix®) is recommended to prevent shingles in adults ages 50 and older. The vaccination is given in two doses, two to six months apart. The two-dose vaccine is 90% effective at preventing shingles and PHN. Protection lasts at least for four years after you get vaccinated.
If you have never had chickenpox or have children who have never had chickenpox, getting the chickenpox vaccine (Varivax) can help prevent getting this infection in the first place. If you never get chickenpox, you will not have the varicella-zoster virus in your body and will not get shingles or PHN.
Who should get the Shingrix vaccine?
The Shringrix vaccine is recommended in healthy adults age 50 and older. There is no maximum age. You should get the vaccine even if:
- You’ve had shingles.
- You’re not sure if you’d had chickenpox (about 99% of Americans over age 40 have had chickenpox, even if they don’t remember getting the disease as a child).
- You’ve already had the Zostavax vaccine. This vaccine for shingles is no longer available in the U.S. Ask your healthcare provider about the best time to get the Shingrix vaccine.
If you currently have shingles, you need to wait until the shingles rash has gone away. Talk with your provider about the proper time to begin vaccination with Shingrix.
Outlook / Prognosis
What outcome can I expect if I have postherpetic pain (PHN)?
There’s no standard treatment for the symptoms of postherpetic pain (PHN). Depending on the severity of your pain, you may start with over-the-counter products. If your pain is more severe, one or more prescription medications may be tried. PHN is difficult to treat. Achieving a complete symptom-free state was achieved in less than half the patients with PHN, according to one study.
PHN tends to happen in older individuals who may have other health conditions, which can complicate treatment and results. Pain can last weeks, months and even longer than a year. In some people, the pain can be debilitating. In most people, PHN lessens with time.
A note from Cleveland Clinic
The best way to not get postherpetic neuralgia (PHN) is to prevent it from happening in the first place. Varicella-zoster virus causes both chickenpox and shingles. Vaccines are available to protect against developing both of these viral infections.
Once you develop chickenpox, the varicella-zoster virus remains in your body for life. If the virus reactivates and causes shingles, you have a few days around the rash outbreak to see your provider and get an antiviral medication, which can significantly lessen your symptoms. Still, if you develop PHN, your provider has many medications available to manage your symptoms.
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