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What is methadone?

Methadone is a long-acting opioid (narcotic) used for pain. Researchers have found that methadone reduces nerve pain. They think it reduces nerve pain better than other opioids, such as morphine. By taking methadone, you may not need as many doses of a fast-acting (immediate-release) opioid. Even so, the doctor will prescribe a fast-acting drug for pain that occurs even while taking methadone. Doctors also use methadone to treat drug addiction.

Methadone is available as a 10-mg white tablet and as a liquid taken by mouth. It is also available as a clear liquid given by vein (IV).

How to take methadone

  • To receive the best pain relief, you must take methadone on a regular schedule as your doctor prescribed.
  • When you are using a fast-acting opioid (such as morphine), you will need to keep a written record of the number of tablets or the amount of liquid medicine that you take each day. Bring this record to your clinic. This record will help the doctor provide the best pain control for you.
  • If stomach upset occurs, take methadone with food.

Possible side effects of methadone


  • Feeling drowsy
  • Nausea
  • Decreased rate of breathing
  • Low blood pressure

Later (usually more than a day after treatment starts)

  • Constipation
  • Itching and hives
  • Feeling drowsy; sedation
  • Feeling dizzy
  • Nausea and vomiting
  • Mood changes (feeling sadder or happier than usual)
  • Dry mouth
  • Fainting
  • Problems urinating

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse.

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Special instructions for methadone

  • If you have any of the side effects listed above, they should decrease after you have taken the methadone for a couple of days. Tell your doctor if the side effects increase while you are taking this medicine. It may mean you need less methadone.
  • If you are taking this medicine regularly, do not stop taking it until the doctor tells you to do so. Stopping methadone without slowly decreasing the dose can lead to diarrhea, headache, sweating, muscle cramps, trouble sleeping, nausea, vomiting, or feeling restless.
  • This medicine may cause you to feel dizzy and drowsy. Do not operate heavy equipment or drive a car until you see how this medicine affects you.
  • If you have not slept well because of your pain, you may sleep more during the first few days of taking this medicine to “catch up” on missed sleep.
  • If you are taking this medicine regularly, you should increase your fluid and fiber intake to help prevent constipation. Tell your doctor or nurse if you have not had a bowel movement in 3 to 5 days. You may need to take a stool softener or laxative to relieve your constipation.
  • If you have taken methadone or other opioids regularly for a long time, your doctor may slowly decrease your dose to wean you off the methadone. During this time, watch for a sudden onset of diarrhea, headache, sweating, muscle cramps, trouble sleeping, nausea, vomiting, or feeling restless. If these symptoms occur, call your doctor right away. It could mean your dose is being decreased too fast.
  • Other medicines can increase the drowsy feeling caused by methadone. These include:
    • Alcohol (found in many over-the-counter cough and cold medicines)
    • Diphenhydramine (over-the-counter Benadryl®
    • Promethazine
    • Diazepam or lorazepam
    • Antidepressants (such as amitriptyline)
    • Medicines used to treat seizures (such as phenytoin, carbamazepine, gabapentin, phenobarbital, and valproic acid).
  • Always tell your doctor if you are taking these medicines or if you start taking any new medicine while taking methadone.
  • This medicine can increase the risk of falls.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).