Postherpetic Neuralgia

What is postherpetic neuralgia?

Postherpetic neuralgia (PHN) is a chronic nerve pain condition that can occur as a complication of shingles infection. It causes persistent pain in the area previously affected by the shingles rash, even after the rash has healed. This pain arises when the varicella-zoster virus (responsible for both chickenpox and shingles) damages nerve fibres during the shingles outbreak. The damaged nerves send abnormal pain signals to the brain, resulting in prolonged or severe discomfort.

Unlike shingles, which involves an active viral rash, PHN is a chronic pain condition that may last for months, sometimes even years. While most people recover from shingles without long-term issues, PHN can significantly affect one’s quality of life.

How common is postherpetic neuralgia?

PHN is the most common complication of shingles. It affects approximately 10 to 20% of individuals who develop shingles, with the risk increasing with age. Among those aged 60 and above, up to 50% may experience PHN following a shingles outbreak.

What are the symptoms of postherpetic neuralgia?

Symptoms of PHN are typically confined to the area where the shingles rash previously occurred. This is most commonly a band-like region on one side of the body, though it can affect the face or other parts of the body as well.

Common symptoms include:

• Persistent pain: The hallmark symptom is pain that lasts more than three months after the shingles rash has healed. This pain may be described as burning, aching, stabbing or throbbing.
• Allodynia: Heightened sensitivity to touch. Even light contact, such as clothing or wind, can trigger significant discomfort.
• Paresthesia: Abnormal sensations such as tingling, numbness or itching.
• Worsening pain with temperature changes: Some individuals report increased pain in response to heat, cold or changes in weather.
• Sleep disturbances and fatigue: Ongoing pain may interfere with rest and lead to exhaustion or low mood over time.

The severity of symptoms varies. Some individuals experience mild, intermittent discomfort, while others face severe, unrelenting pain that interferes with daily activities and emotional wellbeing.

When should you see a doctor?

Consult a healthcare provider if you:

• Have had shingles and continue to experience pain in the affected area beyond three months
• Notice persistent discomfort, burning or tingling sensations even after the shingles rash has resolved
• Are unable to tolerate touch, such as from clothing or bed sheets, in the area of previous shingles

Prompt medical consultation is important to confirm the diagnosis and begin appropriate treatment, which may help reduce pain and prevent complications.

How can postherpetic neuralgia be prevented?

While there is no surefire way to prevent PHN, two strategies can help lower the risk:

• Vaccination: The shingles vaccine (Shingrix) significantly reduces the risk of developing shingles and its complications, including PHN. In clinical studies, Shingrix has been shown to be over 90% effective in preventing both.
• Prompt antiviral treatment: Starting antiviral medications (such as acyclovir, valacyclovir or famciclovir) within 72 hours of shingles onset can help reduce the severity and duration of the infection, and lower the chance of developing PHN.

Who should receive the shingles vaccine?

Shingles vaccination is generally recommended for:

• Adults aged 50 and above
• Adults aged 19 and older with weakened immune systems due to medical conditions or treatments
• Individuals who have previously had shingles

Additionally, those who have received an older shingles vaccine (e.g., Zostavax) may still benefit from Shingrix.

Speak to your doctor about whether the vaccine is right for you and when you should receive it. From September 2025, eligible Singaporeans and Permanent Residents will be able to receive subsidised Shingrix vaccinations at public healthcare institutions and GP clinics under the Community Health Assist Scheme (CHAS).

What causes postherpetic neuralgia?

PHN occurs when the varicella-zoster virus reactivates in the body, typically decades after an initial chickenpox infection, and causes shingles. During a shingles outbreak, the virus can damage peripheral nerves. These nerves then send distorted or exaggerated pain signals to the brain, leading to ongoing discomfort even after the skin has healed.

It is not fully understood why some individuals develop PHN while others do not. The likelihood increases with age and depends on the severity of the shingles episode.

What are the risk factors for postherpetic neuralgia?

Several factors may increase the risk of developing PHN:

• Age: Individuals over the age of 60 are more likely to develop PHN, with the risk rising further in those over 70.
• Severe shingles outbreak: A more intense rash or initial pain during shingles is associated with a higher chance of PHN.
• Delayed antiviral treatment: Not receiving antiviral medications within 72 hours of rash onset may increase the risk.
• Weakened immune system: Conditions such as cancer, HIV or diabetes, or use of immunosuppressive medications, can increase susceptibility.
• Location of rash: Shingles affecting the face or torso may be more likely to lead to PHN.

What are the complications of postherpetic neuralgia?

Individuals with postherpetic neuralgia may develop other issues commonly seen with chronic pain conditions, which can affect physical health, emotional well-being and daily functioning. Depending on the how long the pain lasts and how intense it is, possible complications include:

• Depression
• Insomnia
• Fatigue
• Loss of appetite
• Difficulty concentrating

How is postherpetic neuralgia diagnosed?

There is no specific diagnostic test for PHN. Diagnosis is typically based on:

• A history of shingles, especially in the same area where pain persists
• The duration of pain lasting more than three months after the rash resolves
• A physical examination to assess sensitivity and rule out other causes of nerve pain

How is postherpetic neuralgia treated?

While PHN may resolve gradually over time, treatment focuses on managing and reducing pain to improve quality of life. Because no single treatment works for everyone, a combination of therapies is often used. Your healthcare provider will tailor the approach based on your symptoms, response to prior treatments, and overall health.

Pharmacological therapies
Anticonvulsants
Originally developed for epilepsy, these medications calm overactive nerve signals and are often the first-line treatment for nerve pain:

• Gabapentin (e.g., Neurontin)
• Pregabalin (e.g., Lyrica)

Tricyclic antidepressants
These medications affect chemical messengers in the brain and spinal cord that influence pain perception:

• Amitriptyline
• Nortriptyline

Serotonin-norepinephrine reuptake inhibitors (SNRIs)
A newer class of antidepressants that may help relieve neuropathic pain:

• Duloxetine (Cymbalta)
• Venlafaxine (Effexor XR)

Simple analgesics
These may be used for mild to moderate discomfort or as part of combination therapy.

• Paracetamol
• Non-steroidal anti-inflammatory drugs (NSAIDs)

Opioids
Opioid medications may be considered for short-term use in selected patients with severe pain who do not respond to other treatments. They require close monitoring due to the risk of side effects and dependence.

• Tramadol
• Codeine
• Morphine

Lidocaine patches
Lidocaine (lignocaine) patches are applied directly to the painful area to numb the skin and reduce signals from irritated nerves. They may be helpful for patients unable to tolerate oral medications.

Physical and psychological therapies
Transcutaneous electrical nerve stimulation (TENS)
TENS involves placing small electrodes on the skin to deliver low-level electrical impulses that may reduce pain signals. Patients should consult a pain physician before using TENS, as availability of suitable devices varies and proper guidance is important.

Cognitive behavioural therapy (CBT)
CBT is a structured form of psychological therapy that helps patients understand the connection between thoughts, emotions and physical sensations. It can equip individuals with skills to manage chronic pain, reduce distress and improve functioning.

Self-care strategies:
Simple measures may help reduce discomfort and protect sensitive skin:

• Wear loose, soft clothing (e.g., cotton or silk) to reduce irritation.
• Use cold compresses or take cool baths to soothe the area.
• Apply barrier dressings (e.g., cling film or wound dressings) under clothes to protect sensitive skin.
• Keep a pain diary to monitor symptoms and treatment response.

Acupuncture
Acupuncture involves the insertion of fine needles into specific points on the body. It may help relieve nerve-related pain as well as associated symptoms such as sleep disturbance or anxiety. Electro-acupuncture, which applies a mild electrical current through the needles, may further stimulate the body’s natural pain-relief mechanisms.

Patients who are considering acupuncture should seek treatment from qualified practitioners who have experience managing nerve pain conditions.

Invasive procedures (reserved for severe or refractory cases)
These options are considered when other treatments have not provided adequate relief. They are usually offered by pain specialists after careful evaluation.

Nerve blocks
Nerve blocks involve injecting local anaesthetics or steroids near affected nerves to reduce pain signals. Relief may be temporary, but nerve blocks can assist in managing difficult symptoms or facilitate participation in rehabilitation therapies.

Spinal cord stimulation
A spinal cord stimulator delivers controlled electrical impulses to the spinal cord to modify pain signals before they reach the brain. This procedure is considered only for carefully selected patients with persistent, disabling pain despite multiple treatment attempts.

What can I do to ease my discomfort?

Simple measures that may help ease discomfort include:

• Wearing soft, loose-fitting clothing
• Applying cool packs to the affected area
• Avoiding known triggers such as heat, stress or tight clothing
• Using topical creams as advised by your doctor
• Maintaining good sleep hygiene and mental health

When should I be referred to a specialist?

A referral to a neurologist or pain specialist may be necessary if:

• Pain is severe or persistent despite first-line treatments
• You are unable to carry out daily activities due to pain
• Advanced procedures or therapies are being considered

What is the outlook for patients with postherpetic neuralgia?

The duration and severity of PHN vary widely between individuals. While some experience pain that fades within a few months, others may have persistent symptoms for a year or more. In rare cases, the pain may become chronic.

With appropriate treatment and time, most individuals experience significant relief. However, the condition can be debilitating, particularly in older adults or those with other health conditions.

Ongoing follow-up with a healthcare provider is important to assess treatment effectiveness and adjust the management plan when needed.

Who should get the shingles vaccine?

The shingles vaccine is recommended for individuals who are at higher risk of developing shingles and its complications, including postherpetic neuralgia. These individuals include adults
aged 60 years and above, as well as adults aged 18 to 59 years with weakened immune systems (such as those undergoing chemotherapy or living with certain chronic conditions).

Even individuals who have previously had shingles or received an earlier version of the vaccine (e.g. Zostavax) may benefit from the newer Shingrix vaccine, which is given as a two-dose course.

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