Lidocaine is a local anesthetic that temporarily blocks nerve signals to relieve pain. It is commonly found in creams, gels, and sprays for topical application. A common concern arises when lidocaine is applied to open wounds: some individuals report a burning or stinging sensation. This article explores the reasons behind this feeling and provides guidance on the appropriate use of lidocaine for wound pain relief.
Why Lidocaine Might Feel Like It Burns
The burning or stinging sensation when lidocaine is applied to an open wound often stems from the formulation’s pH. Commercial lidocaine solutions are acidic, especially those containing epinephrine, which prolongs the numbing effect. For instance, lidocaine with epinephrine can have a pH as low as 3.93-4.24, while plain lidocaine is around 6.0-6.1. This acidity contrasts sharply with the body’s natural tissue pH, between 7.3 and 7.6, leading to an initial stinging sensation upon contact.
Preservatives within some lidocaine formulations also contribute to their acidity. Sodium metabisulfite, for example, is used as an antioxidant in lidocaine solutions containing epinephrine. This acidic environment can irritate exposed nerve endings in an open wound before the numbing effect of lidocaine begins. The initial discomfort is usually brief, subsiding as the anesthetic starts to block pain signals effectively.
When to Use Lidocaine on Wounds (and When Not To)
Lidocaine effectively relieves pain for certain minor, superficial wounds. It is commonly used for discomfort associated with scrapes, minor cuts, insect bites, and minor burns. For such injuries, topical lidocaine products provide localized numbing, making the wound more comfortable.
However, lidocaine should be avoided or used with caution in specific situations. It is not recommended for use on large areas of the body, deep wounds, puncture wounds, or severe burns. Applying lidocaine to extensive or severely damaged skin can increase medication absorption into the bloodstream, potentially leading to systemic side effects. Lidocaine should also not be used on grossly contaminated wounds or if there is a known allergy to amide anesthetics. For anything beyond minor injuries, seeking professional medical advice is important to ensure proper wound care and pain management.
Safe Practices for Wound Pain Relief
For minor open wounds, proper cleaning is an important step in pain management and preventing complications. Gently rinse the wound under cool, running water to remove dirt and debris. The skin around the wound can be cleaned with mild soap and water, but soap should be kept out of the wound itself, and harsh antiseptics like hydrogen peroxide or iodine should be avoided as they can damage healing tissue.
After cleaning, applying a thin layer of antibiotic ointment or petroleum jelly helps keep the wound moist and reduces the risk of infection. Covering the wound with a clean bandage also protects it from further contamination and irritation. For pain relief, over-the-counter medications like acetaminophen or ibuprofen can be considered. Non-pharmacological approaches, such as applying a cold compress, can also reduce discomfort.
It is important to seek medical attention if a wound is deep, bleeds profusely and does not stop with pressure, shows signs of infection like increasing redness, swelling, warmth, or pus, or if it does not show signs of healing within a few days. Wounds that impair function or sensation, or those resulting from animal or human bites, also warrant professional medical evaluation.