Numbing creams temporarily reduce sensations in a specific skin area, offering comfort. They are used before minor medical interventions like injections, blood draws, or small surgical procedures. They also apply to cosmetic treatments such as tattooing, piercing, and laser hair removal, or to alleviate discomfort from insect bites and sunburn. Some numbing creams are available over-the-counter, while others require a prescription, depending on their active ingredient concentration.
Mechanism of Action
Numbing creams work by using local anesthetic agents that interfere with the body’s nerve signals. These active ingredients, commonly including lidocaine, prilocaine, benzocaine, and tetracaine, temporarily block pain transmission. Applied to the skin, these agents penetrate to nerve endings.
Once at the nerve cells, these local anesthetics prevent nerve impulse generation and conduction. They achieve this by targeting and blocking voltage-gated sodium channels in nerve cell membranes. Normally, when a nerve impulse is generated, sodium ions rush into the cell through these channels, leading to an electrical signal. By blocking this influx of sodium ions, the anesthetic agents inhibit the nerve from transmitting pain signals to the brain, creating numbness.
The effect of these creams is localized and temporary, meaning only the treated area loses sensation. As the body metabolizes and clears the anesthetic agents, the numbing effect gradually wears off. The duration of numbness can vary, often lasting for several hours after application, depending on the specific ingredients and concentration.
Applying Numbing Cream Safely
Proper application is important for effectiveness and safety. Before application, clean and dry the target skin area for optimal absorption. This removes barriers like dirt or makeup, helping the cream work.
Apply a thin, even layer, ensuring the skin is not visible through the cream. Avoid rubbing it in like lotion; instead, apply it directly to the target area. For enhanced absorption and to keep it in place, covering the treated area with an occlusive dressing, such as plastic wrap or a transparent bandage, is often recommended.
Leave the cream on for a specific duration, typically 30 to 90 minutes, for the numbing effect to take hold. Perform a small patch test on a less sensitive skin area beforehand to check for adverse reactions. After application, wash hands thoroughly to prevent accidental numbing of fingers or contact with sensitive areas like eyes or mouth. Any excess cream should be wiped off before a procedure begins.
Potential Side Effects and Precautions
While generally safe, numbing creams can have side effects. Common, mild reactions at the application site include temporary redness, itching, stinging, or swelling. These minor irritations often resolve on their own.
More serious side effects, though rare, can occur if too much cream is absorbed into the bloodstream. Systemic toxicity can occur if applied to large or broken skin areas, or left on for extended periods. Symptoms of systemic toxicity can include dizziness, drowsiness, blurred vision, ringing in the ears, a metallic taste, increased or irregular heartbeat, headache, confusion, muscle twitching, or even seizures. Allergic reactions, though uncommon, may also occur, presenting as hives, rash, or swelling of the face, lips, tongue, or throat, and can lead to difficulty breathing.
Several precautions are important when using numbing creams, including never ingesting the cream and avoiding contact with eyes, nose, and mouth. Do not apply to broken, irritated, or infected skin without consulting a healthcare provider, as this increases systemic absorption risk. Strict adherence to recommended dosages and application times is important; excessive amounts or prolonged use can lead to serious complications. Keep numbing creams out of reach of children, as accidental ingestion or improper use can be dangerous. Seek immediate medical attention if severe reactions or signs of systemic toxicity occur.