Search Knowledgebase

Topic Contents



Generic NameBrand Name
fentanyl Duragesic

Fentanyl is available as a skin patch, lozenge, pills, shots, a film that dissolves in your mouth, or by IV (intravenous).

Use fentanyl exactly as prescribed by your doctor. This is very important so that you do not get too much of the drug. If you get too much fentanyl in your system, you could have serious problems that can lead to death.

How It Works

Fentanyl acts upon specific receptors in your brain and spinal cord to decrease the feeling of pain and to reduce your emotional response to pain. The action of fentanyl is similar to other drugs in the morphine category (opioids).

Why It Is Used

Fentanyl is used to manage moderate to severe pain, usually in people who have chronic pain. Fentanyl is often used when your other pain medicines no longer work.

How Well It Works

For people with cancer who are already on opioid pain medicine such as morphine or oxycodone, fentanyl works well for treatment of cancer pain.1

Side Effects

Fentanyl has many side effects, including:

  • Drowsiness.
  • Light-headedness.
  • Weakness and fatigue.
  • Feelings of elation (euphoria).
  • Dry mouth.
  • Difficulty urinating.
  • Difficulty breathing.
  • Constipation, which may be severe.
    • Talk with your doctor about using laxatives to prevent constipation.
    • You can prevent constipation at home. Make sure you drink enough fluids. Most adults should drink between 8 and 10 glasses of water or non-caffeinated beverages each day. Include fruits, vegetables, and fibre in your diet each day.
  • Skin reactions, such as irritation, itching, or hives.

Fentanyl should be used with caution by older adults and by people who have lung disease, such as chronic obstructive pulmonary disease (COPD) or asthma.

Fentanyl can cause your body to expect this medicine daily (drug dependency). Dependency is not the same as addiction, which is a behavioural disorder marked by craving a drug.

Reasons not to use fentanyl

Fentanyl can cause serious or life-threatening respiratory problems (hypoventilation). For that reason it should not be used in:

  • Cancer patients who have not been taking continuous opioid pain medicines.
  • The management of acute or postoperative pain, including outpatient surgeries.
  • The management of pain that responds to other pain medicine.
  • Doses greater than 25 mcg per hour at the beginning of opioid therapy.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

In some people, fentanyl impairs balance, coordination, or the ability to think. Do not drive or operate any type of equipment if you are taking fentanyl. If you have severe side effects, call your doctor, and stop taking this medicine.

Do not drink alcohol or use other drugs while you are taking fentanyl.

Fentanyl can interact with many other drugs. Make sure that your doctor is aware of all the medicines you are taking.

Fentanyl should be used during pregnancy only if the benefits to the mother outweigh the risks to the fetus. If you are or may be pregnant, talk with your doctor before using fentanyl. This drug can pass through your body in breast milk and should not be used if you are breast-feeding.

When you remove your fentanyl patch, dispose of it as your doctor tells you to.

Avoid the use of heat, such as a heating pad, electric blanket, hot tub, or sauna, while you are using a fentanyl patch. Heat can increase the amount of fentanyl released from the patch, which causes more risk of serious side effects.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Foley KM, Abernathy A (2008). Management of cancer pain. In VT DeVita Jr et al., eds., DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology, 8th ed., vol. 2, pp. 2757–2790. Philadelphia: Lippincott Williams and Wilkins.


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Michael Seth Rabin, MD - Medical Oncology
Specialist Medical Reviewer Andrew Swan, MD, CCFP, FCFP - Family Medicine
Last Revised May 6, 2010

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.