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Postherpetic Neuralgia

Although herpes zoster is not as contagious as the primary varicella infection, persons with reactivated infection can transmit varicella-zoster virus to nonimmune contacts. About 20 percent of patients with herpes zoster develop postherpetic neuralgia.

Postherpetic neuralgia is defined as pain that persists for longer than one to three months after resolution of the rash. Affected patients usually report constant burning, lancinating pain. Symptoms tend to abate over time. Less than one quarter of patients still experience pain at six months after the herpes zoster eruption, and fewer than one in 20.

Treatment of postherpetic neuralgia

Although postherpetic neuralgia is generally a self-limited condition.

Treatment of Postherpetic Neuralgia

Medication

Dosage

Topical agents

Capsaicin cream (Zostrix)

Apply to affected area three to five times daily.

Lidocaine (Xylocaine) patch

Apply to affected area every 4 to 12 hours as needed.

Tricyclic antidepressants

Amitriptyline (Elavil)

0 to 25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is

Nortriptyline (Pamelor)

0 to 25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is

Imipramine (Tofranil)

25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or

Desipramine (Norpramin)

25 mg orally at bedtime; increase dosage by 25 mg every 2 to 4 weeks until response is adequate, or

Anticonvulsants

Phenytoin (Dilantin)

100 to 300 mg orally at bedtime; increase dosage until response is adequate or blood drug level is 

Carbamazepine (Tegretol)

100 mg orally at bedtime; increase dosage by 100 mg every 3 days until dosage is 200 mg three times daily, response is adequate or blood drug level is 6 to12 :g per mL (25.4 to 50.8 Fmol per L).

Gabapentin (Neurontin)

100 to 300 mg orally at bedtime; increase dosage by 100 to 300 mg every 3 days until dosage is 300 to 900 mg three times daily or response is adequate.

 

Analgesics

Capsaicin (Zostrix-HP), an extract from hot chili peppers, is more efficacious for post-herpetic neuralgia than placebo. Capsaicin cream must be applied.

Lidocaine patches reduce pain intensity, with minimal systemic absorption. The effect lasts only four to 12 hours.

Acetaminophen (eg, Tylenol) and nonsteroidal anti-inflammatory drugs are useful for potentiating the pain-relieving effects.

Tricyclic antidepressants that are commonly used in the treatment of postherpetic neuralgia include amitriptyline (Elavil), nortriptyline (Pamelor), imipramine (Tofranil).

Anticonvulsants. Phenytoin (Dilantin), carbamazepine (Tegretol) and gabapentin (Neurontin) are often used.

Other modalities used to treat post-herpetic neuralgia include transcutaneous electric nerve stimulation (TENS), biofeedback, nerve blocks.