Lidocaine is a widely used local anesthetic that temporarily blocks nerve signals, causing numbness in a specific area. It functions by inhibiting the ionic fluxes necessary for nerve impulse initiation and conduction. Understanding how long the numbing effect of lidocaine lasts is important for managing expectations during and after treatment.
How Long Lidocaine’s Effects Typically Last
The duration of lidocaine’s numbing effect varies depending on its form and how it is administered. Topical lidocaine, available as creams, gels, or patches, provides temporary relief for surface-level pain. Its effects usually last from 30 minutes to a few hours.
When lidocaine is injected, such as for dental work or minor surgical procedures, the numbing sensation generally lasts longer. Plain lidocaine injections typically provide numbness for about 1 to 2 hours. However, if combined with a vasoconstrictor like epinephrine, the duration can extend to 2 to 4 hours. Nerve blocks, which involve injecting lidocaine near specific nerves, can offer relief for several hours, lasting 4 to 5 hours for plain lidocaine nerve blocks and over 10 hours when epinephrine is included.
What Influences Lidocaine’s Duration
Several factors contribute to how long lidocaine’s numbing effects persist. The dosage and concentration of lidocaine administered play a significant role; higher doses and concentrations generally lead to a longer duration of action. The presence of a vasoconstrictor, such as epinephrine, extends the numbing period. Epinephrine constricts blood vessels in the area of injection, which slows down the absorption of lidocaine into the bloodstream. This keeps more of the anesthetic at the nerve site for a longer time, thereby prolonging its effect.
The specific site of application or injection influences absorption and duration. Areas with higher blood flow, such as the front of the mouth, may experience a shorter numbing period. Lidocaine is rapidly absorbed from vascular tissues, and the rate of absorption is affected by the tissue’s vascularity. Individual metabolism affects how quickly the body breaks down and eliminates the drug. The liver primarily metabolizes lidocaine.
After the Numbness: What to Expect
As the effects of lidocaine begin to wear off, sensation typically returns gradually rather than abruptly. Patients may notice a tingling sensation or a feeling of “heaviness” in the treated area as the numbness subsides. This slow return of feeling helps the body adjust and signals that normal sensation is resuming.
While the area is still numb, it is important to take precautions to prevent accidental injury. After dental procedures, avoid eating until full sensation returns to prevent biting the tongue, cheek, or lips. Consuming hot foods or beverages should also be avoided, as the lack of sensation could lead to burns. If numbness persists significantly longer than expected or if any unusual symptoms like a rash or excessive pain develop, contact a healthcare professional.