Lidocaine patches are a form of topical medication delivery that provides targeted pain relief directly through the skin. These adhesive patches contain the local anesthetic lidocaine, which is slowly absorbed into the underlying tissues, reducing pain signals before they reach the central nervous system. This approach manages localized pain without the systemic side effects often associated with oral pain medications. Patches are available in both prescription strength (typically 5%) and lower-strength versions for over-the-counter use (often 4%).
How Lidocaine Patches Work
The effectiveness of a lidocaine patch stems from its ability to interfere with nerve signal transmission. Lidocaine is classified as a local anesthetic, working by stabilizing the membranes of excitable nerve cells in the area of application. Specifically, the compound blocks the voltage-gated sodium channels present in the nerve cell membranes.
By blocking these sodium channels, lidocaine prevents sodium ions from flowing into the nerve cell, which is necessary for generating and sending a pain impulse. This action stops the pain signal from traveling along the nerve fibers to the brain. Since the application is topical, the amount absorbed into the bloodstream is minimal, usually less than five percent, which minimizes systemic side effects and provides localized pain relief.
Specific Pain Conditions Treated
The primary condition for which prescription-strength lidocaine patches are approved is post-herpetic neuralgia (PHN). PHN is a form of chronic nerve pain that persists in the area affected by a shingles outbreak, even after the skin rash has healed. The patch works by calming the damaged, overactive nerve fibers responsible for these neuropathic signals.
While PHN is the main approved indication, lidocaine patches are also widely used to manage other types of localized pain. This includes common musculoskeletal discomfort, such as pain in the lower back, neck, knees, or shoulders due to strains, sprains, or localized arthritis. The topical delivery system is practical when the source of the pain is close to the skin surface. Over-the-counter 4% patches are marketed for the temporary relief of minor aches and pains in these areas.
Proper Application and Duration
Correct application is important to ensure the patch delivers its medication effectively and safely. The patch should be applied directly to clean, dry, and intact skin over the most painful area. Avoid applying the patch to skin that is broken, irritated, cut, or affected by a rash. If the painful area is small, prescription patches can be cut with scissors before the release liner is removed to fit the area.
The typical recommended duration for prescription patches is a 12-hour on and 12-hour off cycle within a 24-hour period. This schedule provides effective pain relief while allowing the skin to recover and minimizing systemic absorption. Patients should not wear more than three prescription patches at one time. For over-the-counter patches, instructions vary, but they are generally applied up to three times a day for no more than eight hours per application.
Important Safety Considerations
The most common side effects are localized skin reactions at the application site, including mild irritation, redness, itching, or a burning sensation. These usually resolve shortly after the patch is removed. If severe irritation occurs, the patch should be removed immediately and not reapplied until the skin is healed.
Although rare, a greater concern is the potential for systemic toxicity if too much lidocaine is absorbed into the bloodstream. This risk increases if patches are used excessively, worn longer than recommended, or applied to broken skin. Signs of excessive systemic absorption can include dizziness, lightheadedness, fast or irregular heartbeat, confusion, or even seizures. Applying heat, such as a heating pad, over the patch can increase the rate of absorption and must be avoided. Used patches still contain medication and must be folded adhesive-side-to-adhesive-side and disposed of safely, away from children and pets, to prevent accidental exposure.