Postherpetic neuralgia (PHN)

What is postherpetic neuralgia?

Postherpetic neuralgia (PHN) is persistent nerve pain that continues in the area of the shingles rash after the blisters have healed. It is the most common complication of shingles.

PHN is defined as pain that persists for 90 days or more after rash onset. The pain can be burning, stabbing, aching, or like electric shocks. Even light touch or clothing against the skin can trigger severe pain (allodynia).

How common is it?

The risk of developing PHN after shingles is approximately 10–18% overall. Risk increases significantly with age:

• Under 40: relatively uncommon
• Age 50–59: about 10%
• Age 60–69: about 13%
• Age 70–79: about 18%
• Age 80+: about 20–25%

Other risk factors

• Severe pain during the acute shingles episode
• Severe or widespread rash
• Rash on the face or eye area
• Delayed antiviral treatment (after 72 hours)
• Immunosuppression

Treatment for PHN

PHN can be difficult to treat and often requires a combination of approaches:

• First-line medications: Gabapentinoids (gabapentin, pregabalin), tricyclic antidepressants (amitriptyline, nortriptyline), or lidocaine patches for localized pain
• Second-line: Tramadol, capsaicin patches (high-concentration, applied by a healthcare professional)
• Non-pharmacological: TENS (modest evidence), cognitive behavioural therapy for coping with chronic pain

Opioids are generally not recommended as first-line treatment and carry risks of dependence. Treatment decisions should be made with a healthcare provider experienced in chronic pain management.

Prevention

The most effective way to reduce PHN risk is vaccination. The recombinant zoster vaccine (Shingrix) reduces the risk of shingles by over 90% — and since fewer people get shingles, fewer develop PHN. Even when shingles occurs after vaccination, the episode is typically milder and shorter.