SN instructed patient and caregiver about Fentanyl Patch. This medication is used to help relieve severe ongoing pain. Fentanyl belongs to a class of drugs known as narcotic ( opiate ) analgesics. It works in the brain to change how your body feels and responds to pain. Use this medication on a regular schedule as directed by your doctor, not as needed for sudden ( breakthrough) pain. Apply this medication to the skin as directed by your doctor. Do not apply on burns, cuts, irritated skin, or skin that has been exposed to radiation ( x-ray treatment ). Select a dry, non - hairy area on a flat part of your body, such as the chest, sides, back, or upper arms. To avoid irritation, apply to a different area each time. Be sure to remove the old patch before applying a new patch. The used patch still contains enough fentanyl to cause serious harm, even kill a child or pet, so fold it in half with the sticky sides together and discard properly. Some side effects are nausea, vomiting, constipation, lightheadedness, dizziness, drowsiness, or headache may occur. Mild irritation, itching, or redness at the application site may also occur. Some of these side effects may decrease after you have been using this medication for a while. If any of these effects persist or worsen, tell your doctor. To prevent constipation, eat a diet adequate in fiber, drink plenty of water, and exercise. Ask your pharmacist for help in selecting a laxative ( such as a stimulant type with stool softener ).