What is the treatment for nerve pain associated with shingles?

Treatment of Nerve Pain Associated with Shingles (Postherpetic Neuralgia)

Gabapentin is the first-line oral pharmacological treatment for postherpetic neuralgia (PHN), starting at 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, then titrating up to 1800-3600 mg/day in three divided doses as needed for pain relief. 1

First-Line Treatment Options

Gabapentin (Preferred First-Line Agent)

• Gabapentin demonstrates efficacy across the 1800-3600 mg/day dose range, with no additional benefit shown above 1800 mg/day. 1
• The medication is FDA-approved specifically for postherpetic neuralgia and has been validated in controlled trials showing significant pain reduction. 2
• Common side effects include somnolence, dizziness, and mental clouding, particularly in elderly patients, requiring careful dose titration and monitoring. 1
• Half tablets not used within 28 days of breaking should be discarded, and the medication can be taken with or without food. 2

Tricyclic Antidepressants (TCAs)

• TCAs have excellent efficacy with a number needed to treat (NNT) of 2.64, making them highly effective for PHN. 1
• Nortriptyline is preferred over amitriptyline due to better tolerability with equivalent analgesic benefit. 1
• Start at 10-25 mg at bedtime and increase every 3-7 days to a final dose of 25-100 mg at bedtime as tolerated, which minimizes daytime sedation effects. 1

Topical Lidocaine Patches

• Topical lidocaine 5% patches provide excellent efficacy (NNT = 2) with minimal systemic absorption, making them particularly suitable for elderly patients or those with comorbidities. 1
• Patches can be worn for 12-24 hours on affected areas, delivering medication gradually over hours and providing localized pain relief. 1

Capsaicin

• Capsaicin is available as an 8% dermal patch or cream and can provide pain relief for at least 12 weeks. 1
• Common side effects include erythema and pain, which can be mitigated by applying 4% lidocaine for 60 minutes before capsaicin application. 1

Second-Line Treatment Options

Pregabalin

• Pregabalin should be considered if patients have an inadequate response to gabapentin, with an NNT of 4.93. 1
• Effective doses typically range from 150-600 mg/day in two divided doses. 1
• Postherpetic neuralgia may persist for months to years, and some patients require long-term treatment with no maximum duration specified in guidelines. 1

Opioids (Use with Caution)

• Certain opioids (oxycodone, extended-release morphine, methadone) show efficacy (NNT = 2.67), but should not be used as first-line agents due to risks of pronociception, cognitive impairment, respiratory depression, endocrine/immunological changes, and potential for misuse and addiction. 1
• Tramadol shows efficacy with an NNT of 4.76 and may be considered as an alternative opioid option. 1

Combination Therapy

• Combining morphine with gabapentin may be more effective when single agents provide inadequate relief, allowing for lower doses of each medication while providing additive effects. 1

Non-Pharmacological Approaches

• Cognitive behavioral therapy (CBT), hypnosis, and physical and occupational therapy are non-pharmacological approaches that may be beneficial for PHN. 1
• Hypnosis is specifically recommended for neuropathic pain management. 1

Critical Pitfalls and Caveats

Medications to Avoid

• Lamotrigine is not recommended for PHN due to lack of convincing evidence of efficacy and risk of lamotrigine-associated rash. 1
• Acyclovir treatment after PHN has developed (beyond the acute shingles phase) has little or no effect on the clinical course of established postherpetic neuralgia. 3

Special Population Considerations

• For elderly patients, start with lower doses and titrate more slowly, with topical treatments being particularly valuable due to minimal systemic effects. 1
• When taking gabapentin with antacids containing aluminum and magnesium (Maalox, Mylanta, Gelusil, Gaviscon, Di-Gel), wait at least 2 hours before taking the next dose of gabapentin. 2

Important Monitoring

• Gabapentin may cause suicidal thoughts or actions in approximately 1 in 500 patients, requiring monitoring for new or worsening depression, anxiety, agitation, or suicidal ideation. 2
• Do not stop gabapentin suddenly without consulting a healthcare provider, as this can cause serious problems including seizures in susceptible patients. 2
• Periodic reassessment of continued therapy is recommended, as postherpetic neuralgia may improve over time. 1

Treatment Algorithm Summary

1. Initiate gabapentin using the standard titration schedule (300 mg day 1,600 mg day 2,900 mg day 3, then increase to 1800-3600 mg/day in divided doses). 1
2. Consider topical lidocaine patches concurrently, especially for localized pain or in elderly patients. 1
3. If gabapentin provides inadequate response, add or switch to nortriptyline (10-25 mg at bedtime, titrate to 25-100 mg). 1
4. If still inadequate, consider pregabalin (150-600 mg/day in two divided doses) or combination therapy with low-dose opioids. 1
5. Reserve opioids for severe, refractory cases due to significant risks. 1