How effective are lidocaine (local anesthetic) patches in managing shingles pain?

Lidocaine Patches for Shingles Pain Management

Lidocaine patches (5%) are effective for postherpetic neuralgia (pain after shingles) and should be considered as first-line therapy, with approximately 60% of patients achieving moderate to complete pain relief. 1, 2

Evidence for Efficacy

For established postherpetic neuralgia (pain lasting >1 month after rash onset), lidocaine patches demonstrate significant benefit:

• The American College of Physicians designates lidocaine patches as first-line treatment for post-herpetic neuralgia, with a number needed to treat (NNT) of 2, indicating excellent efficacy 1
• Approximately 60% of patients achieve moderate to complete pain relief with proper 12-hour daily application 1, 2
• Pain reduction is significant at all time points from 4-12 hours compared to placebo patches 1
• 66% of patients report improvement in pain intensity by Day 7, and an additional 43% who don't initially respond show improvement by Day 14 2
• Pain relief is equally effective regardless of time since shingles onset, though earlier initiation appears prudent 2

Application Protocol

Apply up to 3-4 patches to the painful area for 12 hours within a 24-hour period, then remove to ensure a 12-hour patch-free period: 3, 1

• Patches are available in over-the-counter 4% concentration or prescription 5% strength 3
• Apply only to intact skin—never to broken or inflamed skin 3, 1
• Can be applied to dorsal or plantar surfaces of the affected area 3, 1
• Pharmacokinetic studies confirm systemic lidocaine levels remain within safe range with up to four patches in 24 hours 4, 3

Safety Considerations

Lidocaine patches have minimal systemic absorption and excellent safety profile:

• Adverse reactions are rare, mild, and mostly limited to skin rash 3
• Blood lidocaine concentrations remain low (59-431 ng/ml range in studies) 5, 6
• Similar number of adverse skin reactions in treatment versus placebo groups 5, 6
• Avoid using within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 4, 3

Contraindications include: 3, 1

• Advanced liver failure (decreased clearance)
• Application to broken or inflamed skin
• Known hypersensitivity to amide anesthetics

Monitor for signs of systemic toxicity (rare): 4, 1

• Early signs: circumoral numbness, facial tingling, tinnitus, light-headedness, slurred speech
• Severe signs: muscle twitching, loss of consciousness, respiratory arrest, cardiac arrhythmias

Acute Shingles Pain (During Active Rash)

Limited evidence exists for lidocaine use during acute herpes zoster (active rash phase):

• One small study of 9% lidocaine ointment showed pain reduction from 4-20 hours after application in acute herpes zoster, though not every patient obtained relief 7
• The primary evidence base supports use for postherpetic neuralgia (pain persisting >1 month after rash), not acute shingles 2, 5, 6

When Lidocaine Patches Are Insufficient

If inadequate pain relief after 2 weeks, add or switch to: 1

• Gabapentin: Start 100-300 mg, titrate to 900-3600 mg daily
• Pregabalin: Start 50 mg three times daily, titrate to 100 mg three times daily
• Tricyclic antidepressants: Nortriptyline or desipramine 10-25 mg starting dose, titrate to 50-150 mg
• Capsaicin 8% patch: Single application provides pain relief lasting up to 90 days

Key Clinical Pitfalls

• Don't wait: Although effective in longstanding postherpetic neuralgia, begin therapy as early in the course as possible 2
• Don't apply heat: Avoid excessive heat application over lidocaine patches, as this increases systemic absorption 3, 1
• Don't combine carelessly: Avoid combining with other over-the-counter lidocaine preparations to prevent excessive systemic load 4
• Don't use on damaged skin: Application to broken or inflamed skin is contraindicated 3, 1