Lidocaine Gel for Intrarectal Administration
Lidocaine gel applied intrarectally is NOT an established or recommended route of administration for local anesthesia, and the available evidence shows it is ineffective for most clinical purposes. The evidence specifically demonstrates that topical lidocaine in the rectum does not prevent autonomic dysreflexia during anorectal procedures, whereas perianal/anal sphincter block with lidocaine is effective 1.
Evidence Against Intrarectal Lidocaine Gel
Intrarectal topical lidocaine has been shown to be ineffective in preventing autonomic dysreflexia during anorectal procedures in spinal cord injury patients, according to prior randomized controlled trials 1
A randomized trial demonstrated that lidocaine anal sphincter block (intersphincteric injection) is significantly more effective than placebo, reducing mean maximal systolic blood pressure increase to 22 ± 14 mmHg compared to 47 ± 31 mmHg with placebo (P = 0.01) 1
In prostate biopsy procedures, perianal application of 5% lidocaine cream sufficed for pain control, whereas intrarectal application did not add any benefit 2
Proper Alternative Approaches
For Anorectal Procedures
Use intersphincteric anal block with 1% lidocaine injected into the anal sphincter rather than topical intrarectal application 1
This approach significantly limits autonomic dysreflexia responses in susceptible patients (those with spinal cord injury at T6 or above) 1
For Perianal/Perineal Analgesia
Apply 5% lidocaine cream perianally (externally around the anus) rather than intrarectally 2
Optimal exposure time is 10 minutes for perianal application before procedures 2
Perianal application for 10 minutes provides significant pain reduction during probe insertion and manipulation 2
Safety Considerations for Any Lidocaine Use
Maximum safe dose without epinephrine is 4.5 mg/kg in adults and 1.5-2.0 mg/kg in children 3
Do not use lidocaine within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 3
Monitor for early signs of toxicity including circumoral numbness, facial tingling, slurred speech, tinnitus, and light-headedness 3
More severe toxicity can progress to muscle twitching, loss of consciousness, respiratory arrest, and cardiac arrhythmias 3
Clinical Bottom Line
Intrarectal application of lidocaine gel is not recommended based on available evidence. Instead, use intersphincteric injection for anal procedures or perianal topical application when surface anesthesia is needed 1, 2. The rectal mucosa does not absorb topical lidocaine effectively enough to provide meaningful analgesia for most procedures 1.