Can lidoderm (lidocaine) be applied directly to a shingles rash or is it necessary to wait until the rash has crusted over?

Lidocaine Patch Application for Active Shingles Rash

Lidocaine patches can be safely applied directly to the intact portions of active shingles rash, avoiding areas with open blisters or broken skin. This approach provides effective pain relief during the acute phase of herpes zoster while maintaining safety through topical application with minimal systemic absorption.

Application Guidelines for Active Shingles

Safe Application Technique

• Apply lidocaine 5% patches only to intact skin areas within the painful dermatome, carefully avoiding any blistered or ulcerated regions 1
• The patch should be applied at 12-hour intervals, twice daily, directly to the painful area where skin remains unbroken 1
• This selective application strategy allows pain relief while preventing potential complications from applying medication to damaged skin 1

Evidence for Use During Acute Phase

• A randomized, double-blind study demonstrated that lidocaine 5% patches applied to intact portions of acute herpes zoster lesions (within 4 weeks of onset) produced significant pain reduction compared to vehicle patches 1
• Pain relief was substantial during both rest (mean difference 14.7 points, P=0.005) and movement (mean difference 10.4 points, P=0.007) 1
• The treatment was well tolerated with low incidence of adverse events when applied to intact skin 1
• Additional evidence from Japanese studies using 10% lidocaine gel showed remarkable pain reduction in 93% of patients with acute or subacute herpes zoster, with no adverse systemic reactions or local skin damage 2

Clinical Rationale

Mechanism of Benefit

• Lidocaine patches provide dual benefit through both pharmacological action (local anesthetic effect) and physical barrier protection of sensitized skin 1
• The low systemic absorption profile makes this particularly advantageous for elderly patients or those on multiple medications who may have reduced tolerance for systemic adverse effects 3

Timing Considerations

• Do not wait for the rash to completely resolve before initiating lidocaine patch therapy 1
• Treatment can begin during the acute phase (within 4 weeks of rash onset) as long as intact skin is available for application 1
• Early pain control during acute herpes zoster may help prevent development of postherpetic neuralgia 2

Important Caveats

Areas to Avoid

• Never apply patches directly over open blisters, weeping lesions, or ulcerated skin 1
• Avoid application to areas with active skin breakdown or secondary bacterial infection 4

Complementary Treatment

• Lidocaine patches should be used as an adjunct to, not a replacement for, antiviral therapy (acyclovir, valacyclovir, or famciclovir), which remains the primary treatment for acute herpes zoster 5
• Antivirals are most effective when started within 72 hours of rash onset 5

Monitoring

• Assess the rash daily to identify new areas of intact skin that may benefit from patch application as blistered areas begin to crust over 1
• Watch for local skin reactions at application sites, though these are typically mild 3