Lidocaine patches deliver the anesthetic lidocaine directly through the skin to numb nerves in a specific area, thereby reducing pain signals. They are available in various strengths, with some requiring a prescription (e.g., 5% lidocaine) and others sold over-the-counter (e.g., 4% lidocaine). This topical approach provides sustained pain relief, making them a common choice for managing discomfort.
The Recommended Duration
The duration for which a lidocaine patch can be worn varies based on its strength and whether it is prescription or over-the-counter. Prescription-strength lidocaine patches, typically 5%, are generally applied for a maximum of 12 hours within a 24-hour period. This means following a “12 hours on, 12 hours off” cycle. Up to three 5% patches can be used at one time, covering the painful area.
Over-the-counter (OTC) lidocaine patches, commonly 4% strength, can typically be worn for up to 8 to 12 hours per application. Some OTC products may recommend application up to three times per day, but always follow the specific instructions on the product packaging.
Understanding Why There’s a Limit
Time limits for lidocaine patch application are in place primarily due to the potential for systemic absorption and the risk of local skin reactions. Lidocaine, while applied topically, can be absorbed through the skin and enter the bloodstream. Exceeding the recommended wear time can lead to higher concentrations of lidocaine in the body than intended, increasing the risk of systemic side effects.
Prolonged contact with the skin can also lead to local irritation or adverse reactions at the application site. These can include redness, itching, burning sensations, or even blistering. The prescribed “off” period allows the skin to recover and helps to prevent the accumulation of lidocaine in the body, maintaining safety and effectiveness.
Proper Application and Removal
Before applying, ensure the skin at the chosen site is clean, dry, and intact. Avoid placing the patch on open wounds, cuts, irritated, or red skin, as this can increase lidocaine absorption. It is also advisable to choose an area where the patch will not be rubbed by tight clothing.
After preparing the skin, remove the patch from its pouch and peel off the protective backing, taking care not to touch the medicated side. Apply the patch firmly to the affected area, ensuring all edges adhere well. After the recommended wear time, gently peel the patch off the skin. Fold the used patch in half with the sticky sides together to contain any remaining medication, and dispose of it safely, away from children and pets. Always wash your hands thoroughly after handling the patch.
Safety Considerations and When to Consult a Doctor
Lidocaine patches can cause side effects. Common reactions at the application site include redness, itching, or a burning sensation, which often resolve on their own. More serious systemic side effects can occur if too much lidocaine is absorbed. Signs of systemic toxicity can include numbness around the mouth, dizziness, lightheadedness, confusion, ringing in the ears, blurred vision, or even muscle twitching and seizures.
Individuals with severe liver disease, heart problems, or those taking other medications that affect heart rate or rhythm should use lidocaine patches with caution. Concomitant use of other topical lidocaine products or applying heat sources, such as heating pads, directly over the patch, can increase absorption and risk. A rare but serious blood disorder called methemoglobinemia can also occur. Seek immediate medical attention if severe side effects occur, such as difficulty breathing, swelling of the face or throat, hives, or signs of an overdose. Consulting a doctor is also advised if pain relief is inadequate or if any unusual or persistent symptoms develop.