Optimising Primary Care Management of Postherpetic Neuralgia

Dr Zhang Qianpian
Service Chief @ SKH, SingHealth Duke-NUS Pain Centre;
Head & Consultant, Pain Management Service, Sengkang General Hospital;
Consultant, Department of Anaesthesiology, Singapore General Hospital

A common complication of shingles, postherpetic neuralgia is a chronic condition that affects up to half of people over 60 following a shingles outbreak. Learn how toquickly recognise and manage in primary care and when referral for specialist care maybe appropriate.

WHAT IS POSTHERPETIC NEURALGIA?

Postherpetic neuralgia (PHN) is a chronic nervepain condition that can occur as a complication ofvaricella-zoster virus (VZV) reactivation or shingles.The pain arises when the VZV damages centraland peripheral nervous tissues during the shinglesoutbreak. As a result of nervous tissue destruction, there can be decreased central inhibition of pain signals and peripheral sensitisation leading to persistent pain even after the rash has healed.

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.

INCIDENCES

PHN is the most common complication of shingles. It has an incidence of approximately 10 to 20% in 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. In Singapore, an estimated 4.5% of adults aged 50 and older could develop PHN.

RISK FACTORS

It is not fully understood why some individuals develop PHN while others do not. 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.

SYMPTOMS AND SIGNS 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 and signs 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. 
• Abnormal sensations: Patients may experience pruritus, paraesthesia, dysaesthesia, hyperalgesia and/or hypoesthesia. 
• Allodynia: Pain is produced by non-noxious stimuli. Even light contact, such as clothing or wind, can trigger significant discomfort. 
• Worsening pain with temperature changes: Some individuals report increased pain in response to heat, cold or changes of weather. 
• Sleep disturbances and fatigue: Ongoing pain may interfere with rest and lead to exhaustion or low mood over time.

DIAGNOSIS

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 has resolved

A physical examination to assess sensitivity and rule out other causes of neuropathic pain

Prevention

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 decrease 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 compromised immunity 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.

Since September 2025, eligible Singaporeans and Permanent Residents can receive subsidised Shingrix vaccinations at public healthcare institutions and GP clinics under the Community Health Assist Scheme (CHAS).

Likely Treatment Options by GPs

While PHN may resolve gradually over time, complete resolution of symptoms is rare. Treatment focuses on managing and reducing pain to improve quality of life. A multimodal approach is recommended.

The patient population is older with multiple comorbidities. Adverse effects of medications and interventions should be carefully considered and weighed against any benefits.

Anticonvulsants

Gabapentin and pregabalin are relatively well tolerated by the elderly. They are often prescribed as the initial treatment. Dose adjustment is needed in patients with impaired renal function (see dose adjustment table below).

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

Abbreviation: CrCl, creatinine clearance.

Serotonin-norepinephrine reuptake inhibitors (SNRIs)

A newer class of antidepressants that may help relieve neuropathic pain:

• Duloxetine (Cymbalta) 
• Venlafaxine (Effexor XR)

Tricyclic antidepressants (TCAs)

Elderly patients are more susceptible to the anticholinergic, antihistaminergic and alpha-blocking side effects of TCAs. A lower starting dose should be used followed by slow up-titration, if required.

• Amitriptyline 
• Nortriptyline 
• Desipramine

Other analgesics

Pain relievers may be used in combination with other treatments. These include:

• Paracetamol or paracetamol with codeine (for mild pain) 
• Non-steroidal anti-inflammatory drugs (NSAIDs) 
• Opioids (e.g., tramadol, oxycodone) for short-term or severe cases. These are used cautiously due to risks of dependence and side effects.

PATIENT EDUCATION ON SELF-CARE STRATEGIES

• 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.

WHEN SHOULD THE GP REFER TO A SPECIALIST?

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

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

LIKELY TREATMENT OPTIONS BY THE SPECIALIST

Lidocaine 5% patch: These patches have proven short and long-term efficacy with a favourable side effect profile. They are typically used for mild to moderate pain and can be applied for up to 12 hours each day.

Botulinum toxin (Botox) injections: Botulinum toxin may also help block nerve signals that transmit pain. It is injected into the skin around the affected area and may be considered for patients who do not respond to standard medications. Some studies suggest it can provide relief for several weeks or months.

Cognitive behavioural therapy (CBT): CBT is a psychological therapy that can help individuals cope with chronic pain.

Steroid injections: These may be offered as central neuraxial or peripheral nerve blocks to reduce inflammation and nerve irritation. Steroid injections are generally considered for short-term relief and are used selectively. Their effectiveness in PHN varies from person to person and may require careful monitoring.

Transcutaneous electrical nerve stimulation (TENS): The TENS machine delivers mild, buzzing electrical impulses to the skin, which prevents the nerves from sending abnormal pain messages to the brain.

Acupuncture: Acupuncture, a Traditional Chinese Medicine treatment, may help with PHN-related pain, insomnia and depression symptoms.

REFERENCES

1. Dworkin, R. H., & Schmader, K. E. (2003). Treatment and prevention of postherpetic neuralgia. Clinical Infectious Diseases, 36(7), 877–882. https://doi.org/10.1086/368196 
2. Oh, H., Tan, C., Williams, C., Giannelos, N., & Ng, C. (2024). Public health impact of herpes zoster vaccination on older adults in Singapore: a modeling study. Human Vaccines & Immunotherapeutics, 20(1). https://doi.org/10.1080/21645515.2024.2348839 
3. Forbes, H. J., Bhaskaran, K., Thomas, S. L., Smeeth, L., Clayton, T., Mansfield, K., Minassian, C., & Langan, S. M. (2016). Quantification of risk factors for postherpetic neuralgia in herpes zoster patients. Neurology, 87(1), 94–102. https://doi.org/10.1212/wnl.0000000000002808 
4. Forbes, H. J., Thomas, S. L., Smeeth, L., Clayton, T., Farmer, R., Bhaskaran, K., & Langan, S. M. (2015). A systematic review and meta-analysis of risk factors for postherpetic neuralgia. Pain, 157(1), 30–54. https://doi.org/10.1097/j.pain.0000000000000307 

Dr Zhang Qianpian. With clinical expertise in Anaesthesia, Pain Management and Pain Medicine, Dr Zhang completed her local fellowship in Pain Medicine in 2024. She actively supports both Sengkang General Hospital’s regional anaesthesia service and Singapore General Hospital’s PanORAMA services (PAiN, Obstetrics, Regional Anaesthesia & Miscellaneous Anaesthesia). As Principal Investigator, she leads cutting-edge projects incorporating music therapy and industry collaborations to enhance patient comfort during surgical experiences.

GPs can call our Pain Management Clinics for appointments at the following hotlines for more information:

Singapore General Hospital
Pain Management Centre: 63214377

Changi General Hospital
Chronic Pain Clinic: 6788 3003

Sengkang General Hospital
Pain Management Clinic: 6930 6000

KK Women’s and Children’s Hospital
Women's Pain Centre: 6394 8073
Children's Pain Management Clinic: 6394 8459
Referrals: cpmc@kkh.com.sg