The narcotics in painkiller patches work the same way as those found in pill form and either block the body's pain receptors or change how the body responds, notes MedicineNet.com. The exact way the medicine works depends on the type of drug, but all of the painkiller patches deliver the medication transdermally, meaning it is absorbed into the body via the skin.
Transdermal painkiller patches with lidocaine are sometimes prescribed to relieve chronic pain stemming from a variety of conditions, but fentanyl and buprenorphine are also prescribed. The patches are placed on an area of the body that is flat and without hair. The arms and torso are often recommended, states MedicineNet. How often the patch needs to be changed depends on the dosage, but it's important to dispose of the patch properly as it will still contain some of the medication. Exposing the patch to heat can increase the rate of absorption and cause adverse reactions.
Some of the painkillers used in the patches can be habit forming, so it's important to notify the prescriber if it appears that the dose is not as effective over a period of time. Patients should inform their doctors about any other medications or supplements they are taking, especially substances with a sedative effect, notes Drugs.com.