Dermatologists frequently employ various methods to numb the skin, ensuring patient comfort during a range of procedures.
Types of Numbing Agents
Dermatologists utilize several categories of numbing agents to prepare the skin for procedures. Topical anesthetics are applied directly to the skin’s surface and are commonly used for superficial numbing. These often contain active ingredients such as lidocaine, prilocaine, benzocaine, or tetracaine, sometimes in combinations like EMLA cream or compounded BLT gels.
For deeper or more extensive numbing, dermatologists often use injectable local anesthetics. Lidocaine is the most common medication in this category, frequently combined with epinephrine (adrenaline). The addition of epinephrine helps to constrict blood vessels, which prolongs the numbing effect and reduces bleeding at the treatment site. Other injectable options include bupivacaine, used when a longer duration of action is desired. Beyond chemical agents, some dermatologists also use cryo-anesthesia, which involves applying cold through sprays or ice, to temporarily numb the skin surface.
How Numbing Agents Work
Numbing agents function by temporarily interrupting the transmission of pain signals in the treated area. These substances primarily target specific channels within nerve cell membranes, particularly the voltage-gated sodium channels. By binding to these channels, the agents prevent sodium ions from flowing into the nerve cells. This blockade stops the nerve from generating and conducting electrical impulses, which are the signals the brain interprets as pain.
This effect is reversible, meaning that once the numbing agent is metabolized or clears from the tissue, normal nerve function and sensation return. Topical anesthetics primarily affect free nerve endings in the superficial layers of the skin, while injectable anesthetics can reach deeper nerves and a larger area.
Procedures Where Numbing is Applied
Minor surgical procedures, such as skin biopsies and mole excisions, frequently use injectable anesthetics to numb the specific area.
Laser treatments, including those for hair removal, skin resurfacing, and tattoo removal, often benefit from topical numbing creams to manage discomfort. Cosmetic injectables, such as dermal fillers and neuromodulators like Botox, also commonly utilize topical anesthetics or sometimes lidocaine mixed directly into the filler product to minimize the sting of the needle. Procedures like microneedling and wart removal are also made more comfortable with the use of numbing agents.
Application Methods and What to Expect
The method of applying numbing agents varies depending on the type of anesthetic and the procedure. Topical creams and gels are spread onto the skin surface, often requiring an application time of 20 to 60 minutes for sufficient numbing, with some formulations needing up to two hours for deeper penetration. For enhanced absorption, the treated area may be covered with an occlusive dressing. Once the numbing takes effect, the cream or gel is typically wiped away before the procedure begins.
Injectable numbing involves a small needle delivering the anesthetic directly into or under the skin. Patients typically feel a brief stinging or pressure sensation as the solution is injected, followed by rapid numbness, often within seconds to a minute. The numbing effect from injectable lidocaine usually lasts between one to three hours, though this can vary based on the dosage, injection site, and whether epinephrine was added. After the procedure, the numb sensation gradually resolves over a few hours, and patients are advised to be careful with the treated area until full sensation returns.