Lidocaine cream is a topical anesthetic used to numb the skin, making minor medical or cosmetic procedures more comfortable. It is frequently applied before injections, blood draws, laser treatments, or tattoo sessions to minimize pain perception. The active ingredient, lidocaine, temporarily blocks nerve signals in the area where it is applied. This localized numbing effect prevents pain sensations from traveling to the brain, providing temporary relief for surface-level discomfort.
Understanding the Mechanism and Variables Affecting Speed
Lidocaine works by stabilizing the neuronal membrane, preventing sodium ion channels in nerve cells from opening. By inhibiting the flow of sodium ions, the cream blocks the initiation and conduction of electrical impulses, effectively stopping the transmission of pain signals to the central nervous system. This action requires lidocaine molecules to penetrate the outer layer of the skin to reach the underlying nerve endings.
The speed of onset is influenced by several factors. The concentration of the cream, typically ranging from 2% to 5%, directly affects absorption, with higher concentrations leading to a faster onset. Skin thickness also plays a role; thinner areas, such as the forearm, allow for quicker penetration than thicker skin, like the palms or soles of the feet. Covering the cream with an occlusive dressing, such as plastic wrap, traps moisture and heat, significantly enhancing drug absorption and speeding up the numbing process.
Typical Timeline for Onset and Duration of Effect
The initial sensation of numbing usually begins within a short window, often between 5 and 15 minutes after application. During this time, users may notice a slight tingling or cooling sensation as the lidocaine starts to penetrate the superficial layers of the skin. However, this early stage does not represent the full anesthetic effect needed for procedures.
For robust numbing, the cream requires a longer period to reach its peak anesthetic effect. This peak is generally achieved after 30 to 60 minutes, especially when using a higher concentration cream with an occlusive dressing. The depth of the numbing can reach several millimeters into the skin after a full hour of application.
Once the cream is removed, the duration of the numbing effect is intermediate, lasting on average from one to three hours. This duration varies based on the total amount of lidocaine absorbed, the specific formulation used, and the blood flow in the treated area. The numbing effect slowly diminishes as the body metabolizes and clears the lidocaine from the tissue.
Maximizing Effectiveness Through Proper Application
To achieve the fastest and most profound numbing effect, proper application is necessary. Start with clean, dry skin free of oils or lotions; the skin should be gently washed and patted dry before applying the cream to ensure optimal contact and absorption.
The cream should be applied in a thick, visible layer, not massaged or rubbed fully into the skin like a moisturizer. The goal is to create a reservoir of the drug on the skin’s surface, allowing it to passively diffuse into the deeper layers. Gently squeezing the tube and spreading the cream without rubbing it in prevents premature absorption and ensures a dense layer remains.
For deeper numbing, an occlusive dressing, such as plastic film, must be placed directly over the thick layer of cream. This dressing prevents the cream from drying out and enhances penetration. The cream and dressing should be left in place for the full recommended time (typically 30 to 60 minutes), and the excess cream must be wiped away completely before the procedure begins.
Safety Considerations and Signs of Systemic Absorption
Topical lidocaine cream is generally safe when used as directed, but improper use can lead to systemic absorption, meaning the drug enters the bloodstream. The risk is higher if the cream is applied to large areas, used on broken skin, or left on for excessive periods. Following dosage limits set by the manufacturer or healthcare professional is important to mitigate this risk.
Common, local side effects are minor and include temporary redness, mild irritation, or a pale appearance of the skin. More serious signs of systemic toxicity, although rare, primarily affect the central nervous system and the cardiovascular system. These symptoms include dizziness, confusion, ringing in the ears, a metallic taste in the mouth, or an irregular heartbeat. Recognizing these signs and seeking immediate medical attention is necessary if they appear after using the cream.