 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  Fentanyl belongs to a class of drugs known as opioid analgesics. It works in the brain to change how your body feels and responds to pain.This medication should not be used to relieve mild or short-term pain (such as due to headache/migraine, dental procedures, surgery). How to use Fentora Tablet, Effervescent Read the Medication Guide provided by your pharmacist before you start using fentanyl and each time you get a refill. Learn all usage and disposal instructions. If you have any questions, ask your doctor or pharmacist. Use this medication as directed by your doctor. Just before using, open the blister pack unit as directed. Do not push the tablet through the foil of the blister pack because this could damage the tablet. Place the tablet in your mouth either above a rear molar tooth between your upper cheek and gum or under the tongue. Leave the medication in place until it is dissolved (usually 14 to 25 minutes). Do not break, bite, chew, suck, or swallow the tablet whole. You may feel a gentle bubbling in your mouth while the tablet dissolves. Do not eat or drink anything while the tablet dissolves. If there is still some tablet left after 30 minutes, swallow it with a glass of water </s>