A lidocaine patch is a topical, adhesive medication designed to deliver the local anesthetic lidocaine directly through the skin for targeted pain relief. This non-invasive approach provides a localized concentration of medication at the source of discomfort. The patches are a popular method for managing certain types of chronic pain, offering an alternative to oral medications that affect the entire body. Both prescription-strength (5%) and lower-strength over-the-counter (4%) versions are available for managing ongoing, specific areas of pain.
How Lidocaine Patches Stop Pain
The active ingredient is lidocaine, an amide class local anesthetic. Lidocaine works by inhibiting the flow of sodium ions into the nerve cells located beneath the patch. These ions are necessary for initiating and conducting pain signals.
By blocking these voltage-gated sodium channels, lidocaine effectively suppresses the transmission of pain impulses from the application site to the brain. The patch functions as a transdermal delivery system, releasing the medication steadily over time. This method minimizes the amount of drug that enters the systemic circulation compared to pills, which helps reduce the risk of widespread side effects. The analgesic effect is concentrated locally, providing relief without causing generalized numbness.
Approved Conditions for Treatment
The primary FDA-approved indication for prescription-strength lidocaine patches (5%) is for the management of pain associated with post-herpetic neuralgia (PHN). PHN is a chronic, painful condition that persists after a shingles infection has resolved. The patch provides relief by calming the damaged, overly sensitive nerve fibers that cause the characteristic burning and stabbing pain.
While PHN is the only FDA-approved use, these patches are commonly used off-label to treat other forms of localized neuropathic or musculoskeletal pain. Clinicians may prescribe them for conditions such as chronic low back pain, diabetic peripheral neuropathy, or localized pain from osteoarthritis. Over-the-counter patches (4%) are intended for temporary relief of minor aches and pains in muscles and joints.
Proper Application and Removal
Proper application and removal are important for both the safety and effectiveness of the lidocaine patch. The patch must be applied to clean, dry, intact skin that is free from cuts, rashes, or irritation. Applying the patch to broken skin significantly increases the absorption of lidocaine into the bloodstream, raising the risk of adverse reactions.
For prescription versions, the standard regimen involves wearing the patch for no more than 12 hours within any 24-hour period, followed by a 12-hour patch-free interval. This on-and-off cycle is important to prevent the skin from becoming overly saturated with the medication, which could lead to increased systemic absorption. Patches can often be cut with scissors to fit the painful area, but never apply more than the maximum number prescribed at one time, usually three.
When the wear time is complete, the patch should be removed carefully. Used patches still contain residual medication and must be disposed of safely. To prevent accidental exposure to children or pets, fold the used patch in half, adhesive sides together, before discarding it. Wash your hands immediately after handling both new and used patches to avoid transferring the medication to your eyes or mouth.
Safety Warnings and Adverse Reactions
Most side effects related to lidocaine patches are localized and mild, occurring at the application site itself. These common reactions include temporary skin redness, irritation, swelling, or a burning sensation. If severe irritation or blistering develops, the patch should be removed immediately, and a healthcare provider should be consulted.
A serious concern is the systemic absorption of too much lidocaine, which can occur if the patch is worn too long or if too many patches are used. Signs of potential over-absorption include dizziness, confusion, changes in heart rate, or a metallic taste. Heat exposure, such as from using a heating pad or electric blanket over the patch, can accelerate the rate at which lidocaine is absorbed into the body, increasing the chance of serious side effects. Patients should also be aware of the extremely rare risk of methemoglobinemia, a serious blood disorder that impairs oxygen delivery.