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Trade/other name(s): Dolophine, Methadose

Why would this drug be used?

Methadone is used to treat severe pain. It may also be used for other purposes.

How does this drug work?

Methadone is a man-made (synthetic) opioid pain reliever that works very much like morphine. It binds to opioid receptors in the brain and central nervous system (CNS), which reduces both the perception of and emotional response to pain.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have any medical conditions such as kidney disease, liver disease (including hepatitis), enlarged heart, low thyroid function, or Addison's disease (low adrenal function). These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you have asthma, emphysema, chronic bronchitis, sleep apnea, or other serious breathing problems. You should not take methadone because it can worsen these problems, and you could even stop breathing.
  • If you have an abnormal heart rhythm, especially a disorder of the heart's electrical system called prolonged Q-T interval. You may need closer monitoring during treatment.
  • If you have problems with the amount of magnesium or potassium in your blood. Low levels of these minerals can increase the risk methadone will affect heart rhythm.
  • If you have had abdominal pain or any disorder with slowed or blocked intestines, such as paralytic ileus. Methadone can worsen this problem.
  • If you have trouble passing your urine, narrow urethra, or if you have an enlarged prostate. Methadone can make it harder to urinate.
  • If you have ever had a seizure, head injury, or if you have had problems with pressure, infection, or a tumor in your head or brain. Methadone can raise your risk of seizures.
  • If you have low blood pressure. Methadone can worsen this.
  • If you have gallstones, gallbladder disease, or pancreatitis. Methadone can sometimes worsen these problems.
  • If you drink alcohol or take any medicine that can affect your brain or nervous system. These may worsen the side effects of methadone or cause other problems.
  • If you have trouble with addiction, alcohol, or drug abuse now or have had one in the past. Methadone can be habit forming, especially for those who have had problems before.
  • If you have taken monoamine oxidase inhibitors within the past 2 weeks (see drug interactions section, below.) Methadone can cause coma, slow or shallow breathing, low blood pressure, excitability, seizures, or shock.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of harm to the fetus if a woman takes this drug during pregnancy, especially later in pregnancy.
  • If you are breast-feeding. The drug passes into breast milk and may affect the baby.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Methadone interacts with a number of different drugs, some in very dangerous ways.

Several different medicines can cause the blood level of methadone to go very high and increase the risk of serious side effects or overdose:

  • antibiotics such as erythromycin
  • anti-fungals such as itraconazole, ketoconazole, and voriconazole
  • antidepressants such as sertraline and fluvoxamine
  • blood pressure and heart medicines such as verapamil and diltiazem (calcium channel blockers)

When you are on any of these medicines and are being treated with methadone, your dose of methadone may need to be lowered to avoid serious side effects. There may be other medicines with this effect that are not on this list.

Antidepressants of the older MAO inhibitor type such as phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), or selegiline (Emsam) may cause coma, slow or shallow breathing, low blood pressure, excitability, seizures, or shock if methadone is given within 2 weeks of the last MAO inhibitor dose.

Medicines or substances that slow down the brain or nervous system, such as these, can cause worse side effects if taken with methadone:

  • anti-anxiety drugs (sedatives or tranquilizers)
  • sleeping pills
  • muscle relaxers
  • barbiturates
  • anti-seizure medicines
  • other opioid drugs
  • anesthetics
  • tricyclic antidepressants such as amitriptyline, desipramine, doxepin, imipramine, nortriptyline
  • anti-psychotic drugs
  • certain anti-nausea medicines
  • alcohol

Some of these can cause slowed breathing, low blood pressure, extreme sleepiness, coma, or even death if taken with methadone.

If you are taking "water pills" (diuretics) or laxatives, methadone is more likely to affect your heart rhythm.

Some substances may lower the blood level of methadone:

  • anti-seizure medicines such as phenobarbital, carbamazepine, and phenytoin
  • TB medicines rifampin and rifabutin
  • HIV medicines such as ritonavir, indinavir, nelfinavir, efavirenz, nevirapine
  • steroid drugs such as dexamethasone
  • St. John's wort

Your doctor will decide if your methadone dose should be changed to control pain and avoid withdrawal symptoms.

Buprenorphine (Subutex, Suboxone), butorphanol (Stadol), nalbuphine (Nubain), or pentazocine (Talwin, Talacen) may reduce the effectiveness of methadone. They can cause withdrawal symptoms if you have taken the methadone for some time.

Methadone can also affect other drugs that you may be taking; for instance, methadone can cause desipramine and zidovudine to build up in the body and raise your risk of problem side effects. It can lower the levels of other drugs such as didanosine (for HIV).

Check with your doctor, nurse, or pharmacist about whether other medicines, vitamins, herbs, and supplements can cause problems with this medicine.

Interactions with foods

Grapefruit or grapefruit juice may raise the level of this drug in your body. This can worsen any bad effects the drug may have on you and may increase its action in a harmful way. Check with your doctor, nurse, or pharmacist about whether other foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Methadone is given several ways: as a pill or liquid by mouth, or as an injection in a vein, muscle, or under the skin. If you are taking the oral concentrate solution, measure carefully using the dropper from the pharmacy, and mix your dose in at least an ounce or two of water or juice. If you are using dissolving tablets, place your dose into water or juice and wait a minute for the tablet to dissolve before you drink it. If any bits are left behind, swirl in a bit more fluid and drink it.

Your doctor will select your dose depending on how well your pain is controlled by methadone. You may be started on a lower dose and have it slowly increased over a few days or weeks.

Take this drug exactly as prescribed by your doctor. If you have any questions or do not understand the instructions, talk to your doctor or nurse. Store the medicine in a tightly closed container away from heat and moisture and out of the reach of children, pets, and others. Never let anyone else share your medicine.


Always talk with your doctor before starting or stopping any medicines while on methadone. Because some drugs cause methadone to build up in the body, you can get too much methadone and have serious side effects or even overdose. Other drugs can cause methadone to leave the body faster so that your pain is not controlled.

Since methadone affects the central nervous system, do not take other drugs or substances that slow down the brain or nervous system such as alcohol, sedatives, muscle relaxers, and sleeping medicines unless your doctor tells you to do so. Combining these drugs with methadone can slow down breathing and lower blood pressure even more. Keep in mind that methadone's effects on your breathing often last longer than the pain relief. Pain relief effects start to last longer after you have taken it for several days.

This medicine can cause drowsiness and lightheadedness. Do not drive, operate machinery, or perform other activities that require alertness until you know how you react to this medicine.

Methadone can make you feel dizzy or faint, and increase your risk of falling. Be careful getting up, changing position, or walking. Get up slowly and hold onto something or someone to keep you steady. If you feel lightheaded or dizzy, it may help to lie down. It is best to have a responsible adult with you for the first 2 or 3 days after starting the methadone or after any increase in dose, until you know how you will respond to it.

Call your doctor right away if you have trouble breathing, get short of breath, dizzy, faint, get confused, feel very drowsy, or start seeing or hearing things that aren't there.. These may be signs your dose is too high, or you could have gotten an accidental overdose of the medicine.

Tell your doctor or nurse right away if you have trouble passing your urine, trouble walking, vision problems, fainting, trouble swallowing, or other problems.

Patients should be instructed to seek medical attention immediately if they experience symptoms suggestive of an arrhythmia (such as palpitations, dizziness, lightheadedness, or syncope) when taking methadone.

If you are planning any kind of surgery, be sure to tell the doctor or dentist in charge that you are using this medicine.

Constipation is a very common side effect of taking opioid pain medicines. While you're taking methadone, you should take a stool softener, bulk-forming agent, and a laxative to help keep bowel movements regular. Talk to your nurse or doctor about this when you first start this medicine. Drink plenty of fluids throughout the day, and try to eat foods high in fiber such as whole grains, bran, fruits, and vegetables. If you have not moved your bowels in 2 days, call your doctor or nurse immediately.

Most cancer pain can be controlled. Keep your doctor or nurse informed about how well your pain medicines are working and any side effects you are having. Your cancer team may need to adjust your medicines several times before they find the medicines that work best for you.

If you have chronic (long term) cancer pain, talk with your doctor or nurse about taking your pain medicines on a regular schedule to keep it from worsening. If you wait until the pain is bad, it takes more medicine to get it under control. If pain comes back between doses, talk to your cancer team about changing your medicine or adding an extra one for "breakthrough" pain.

Talk to your doctor or nurse about using the smallest effective dose to reduce side effects. Tolerance (larger doses needed to give the same effect) and physical dependence (body goes into withdrawal if drug is suddenly stopped) develop when strong (opioid) medicines are taken over several weeks to treat chronic pain. However, tolerance and physical dependence aren't the same as addiction, which is psychological dependence (when drug is taken for psychological effect, not for relief of pain). Tell your doctor or nurse if you still have pain even though you are taking the medicine as prescribed. Do not adjust your dose without talking to your doctor or nurse first.

Do not stop taking this medicine without talking to your doctor or nurse. When it is no longer needed, this medicine should be stopped gradually with the help of your doctor. If it is stopped suddenly, withdrawal symptoms may occur, such as restlessness, irritability, anxiety, runny nose, watering eyes, yawning, sweating, chills, gooseflesh, aches, nausea, vomiting, poor appetite, high blood pressure, fast heartbeat, and fast breathing.

Acetaminophen or aspirin may be taken along with methadone to increase the pain relief action. It is important to know if any of your other medicines contain either of these drugs. Aspirin and acetaminophen are in many remedies and it is easy to accidentally get too much of them. Check with your doctor, nurse, or pharmacist to find out which of these drugs are included in your daily medicines.

This drug is a controlled substance, and may be habit forming. Do not allow others to take your medicine. A person who has taken methadone for some time often needs large doses for pain relief, while the same amount could quickly kill someone else.

If you think you or someone else may have taken an overdose of methadone, get emergency help right away. Symptoms of methadone overdose may include extreme drowsiness, slow heart beat, slow or irregular breathing, cold clammy skin, or coma. Methadone overdose may cause the heart or breathing to stop. The patient may need to be watched and treated for many hours because of how long methadone stays in the body.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • constipation*
  • drowsiness
  • sedation*
  • nausea
  • dizziness*
  • dry mouth

Less common

  • vomiting
  • changes in mood
  • euphoria
  • depression
  • mental clouding, confusion*
  • slow or shallow breathing*
  • low blood pressure with dizziness when sitting up or standing*
  • delayed digestion
  • slow heart rate


  • difficulty urinating
  • seizures
  • decreased sexual interest
  • impotence
  • death due to slow or shallow breathing*

*See "Precautions" section for more detailed information.

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984. (The FDA cannot verify dates of drugs approved before 1984.)

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 11/10/2009
Last Revised: 11/10/2009