Lidocaine 5% patches temporarily relieve minor pain by penetrating the skin and acting on painful sites. Very little of the drug enters the bloodstream, so the effect stays contained to the location of the patch. As of 2015, the exact process by which this happens is unknown.
Lidocaine patches, in brands such as Lidoderm, LenzaPatch and Terocin, are used to relieve muscle and joint pain caused by arthritis, back pain, and problems caused by tendon or nerve damage, says Drugs.com. Endo Pharmaceuticals, the manufacturer of Lidoderm, also indicates it for nerve damage caused specifically by shingles. Since it acts only on the area around where the patch is applied, when used correctly very little lidocaine enters the rest of the body, which prevents it from interacting with other medications. This is essential for this medication, as a doctor may prescribe oral pain relievers to be taken with the patch.
Patches are applied to clean, dry, intact skin only, as they may cause further damage if applied to wounds or infected areas. Although side effects are rare, some include allergic reaction and stinging, tingling or numbness at the application site, says Drugs.com. In the United States, lidocaine 5% patches are a prescription drug only, and should only be taken by patients who have had them prescribed by a doctor.