Lidocaine patches are common topical medications used for pain relief, available as 5% prescription or 4% over-the-counter versions. These patches deliver medication directly to the affected area, providing localized pain relief. This article explores how lidocaine patches work and addresses their potential influence on blood pressure.
Understanding Lidocaine Patches and Systemic Absorption
Lidocaine patches are topical analgesics applied to the skin for pain relief. They work by blocking sodium channels in damaged nerve fibers, which reduces abnormal nerve firing and associated pain signals. This localized action provides pain relief without causing widespread effects throughout the body.
While the main goal is local pain relief, a small amount of lidocaine from the patch can be absorbed into the bloodstream, a process known as systemic absorption. Studies indicate that less than 5% of the lidocaine from a patch is absorbed systemically. This minimal absorption means the amount of lidocaine reaching the bloodstream is insufficient to cause widespread systemic effects.
Several factors can influence systemic absorption. Applying patches to broken, irritated, or inflamed skin can lead to higher absorption. The duration of application, number of patches used, skin thickness, surface area, and local blood supply also affect absorption rates.
Lidocaine Patch and Blood Pressure: The Evidence
For most individuals using lidocaine patches as directed, significant increases in blood pressure are not common. The low systemic absorption of lidocaine from topical patches keeps blood concentrations well below levels that affect the cardiovascular system. For instance, the average peak blood concentration from a properly used 5% patch is around 0.13 µg/mL, significantly lower than the 5 µg/mL concentration associated with toxicity.
While intravenous lidocaine in high doses can influence the cardiovascular system, potentially causing a temporary drop or increase in blood pressure, this is generally not the case with topical patches. The controlled and limited release of lidocaine from a patch minimizes the risk of such systemic effects. Rare instances, such as in patients with pre-existing heart conditions or improper patch use, might lead to a blood pressure effect. However, for most users following instructions, these occurrences are exceptions.
Important Considerations and When to Consult a Doctor
When using lidocaine patches, localized side effects may occur at the application site. These can include skin irritation, redness, blistering, bruising, or a burning sensation. These reactions usually subside within minutes to hours.
To minimize systemic absorption and potential side effects, follow dosage instructions carefully. Patches should be applied to clean, dry, intact skin, avoiding inflamed, broken, or infected areas. Avoid applying heat sources, such as heating pads or electric blankets, over the patches, as this could increase lidocaine absorption.
Consult a healthcare professional if you have pre-existing cardiovascular conditions, as this may increase the risk of certain side effects. Seek medical attention if you experience unusual symptoms such as dizziness, lightheadedness, confusion, blurred vision, ringing in the ears, or changes in heart rate while using the patch. Any significant changes in blood pressure or other systemic symptoms should be discussed with a doctor promptly.