Does topical application of lidocaine (local anesthetic) to a wound cause numbness?

From the Guidelines

Yes, topical application of lidocaine to a wound causes numbness. Lidocaine is a local anesthetic that works by temporarily blocking nerve signals in the area where it's applied, reducing pain sensation.

Key Points

• When applied topically to a wound, lidocaine typically begins working within 2 minutes and can provide numbness for about 30-45 minutes, depending on the concentration used 1.
• The medication works by inhibiting sodium channels in nerve cell membranes, preventing the generation and conduction of pain signals.
• Common formulations include lidocaine solutions or gels, which can be applied directly to wounds.
• While generally safe for most people, some individuals may experience mild burning upon application before the numbing effect begins.
• Lidocaine should be used cautiously in large wounds or on mucous membranes as excessive absorption could potentially cause systemic effects.
• The numbing effect is temporary and will gradually wear off as the medication is metabolized by the body.

Considerations

• According to the guidelines for the use of local anesthesia in office-based dermatologic surgery, lidocaine is a suitable option for topical use, with an onset of 2 minutes and a duration of 30-45 minutes 1.
• Another study on relief of pain and anxiety in pediatric patients in emergency medical systems also supports the use of lidocaine as a topical anesthetic for open wounds, with a recommended dose and application procedure 1.
• However, it is essential to follow the recommended guidelines and precautions to minimize the risk of adverse events.
• In terms of morbidity, mortality, and quality of life, the use of lidocaine as a topical anesthetic can improve patient outcomes by reducing pain and discomfort during wound treatment, which can lead to better wound healing and reduced risk of complications.
• Overall, the benefits of using lidocaine as a topical anesthetic for wound treatment outweigh the potential risks, making it a recommended option for clinicians.

From the FDA Drug Label

Helps to Numb Away Pain

• Numbness is a expected effect of topical application of lidocaine, as indicated by the phrase "Helps to Numb Away Pain" on the label.
• The active ingredient is 4% lidocaine, which is a local anesthetic. The topical application of lidocaine to a wound is intended to cause numbness, thereby relieving pain 2.

From the Research

Topical Application of Lidocaine

• The effect of topical application of lidocaine on wound healing and emergence from general anesthesia has been studied in various experiments 3, 4.
• A study on rats found that topical application of lidocaine prolonged the time to extubation without delaying the appearance of eyelid reflex 3.
• Another study on guinea pigs found that local infiltration of lidocaine produced significant histopathologic changes, but did not substantially alter wound healing 4.

Local Anesthetic Effects

• Lidocaine is a local anesthetic that can be used to numb the skin and reduce pain during medical procedures 5, 6.
• The absorption of lidocaine can vary significantly between individuals, and some people may experience high absorption levels 7.
• Topical anesthetics, including those containing lidocaine, can be effective in reducing pain and discomfort during wound repair 5, 6.

Wound Healing and Numbness

• The application of lidocaine to a wound can cause numbness, but the effect on wound healing is not well established 4.
• A study found that lidocaine did not substantially alter wound healing, but produced significant histopathologic changes 4.
• More research is needed to fully understand the effects of topical lidocaine on wound healing and numbness 5, 6, 7, 3, 4.