phn

Postherpetic neuralgia (PHN) is a form of chronic neuropathic pain that persists after the acute phase of herpes zoster (shingles) has resolved. By convention, PHN refers to pain lasting three months or longer after onset of the shingles rash.

PHN results from nerve damage caused by reactivation of the varicella zoster virus. Risk factors include older age, severe acute zoster, extensive rash, and immunosuppression. The condition is more common in people over 60.

Symptoms include a burning, stabbing, or electric shock-like pain in the area previously affected by shingles, often accompanied by allodynia (pain from light touch) and sensory changes.

Diagnosis is clinical, based on history and examination. Other causes of persistent facial or body pain may be considered if the presentation is atypical. Management aims to reduce pain and improve function and often uses multiple modalities. First-line options include gabapentinoids (gabapentin, pregabalin), antidepressants (amitriptyline, nortriptyline, duloxetine), and topical lidocaine or capsaicin patches. Nonpharmacologic approaches such as physical therapy and psychological support can help. Opioids are generally avoided as first-line therapy and reserved for refractory cases. In selected patients, interventional treatments such as nerve blocks or spinal cord stimulation may be considered.

Prevention: vaccination against shingles with the recombinant zoster vaccine (Shingrix) reduces the risk of herpes zoster and PHN. Prognosis: PHN is variable; many patients experience gradual improvement over months, while some have pain persisting for years.