Health Guide

Methadone (By injection)

Methadone (METH-a-done)

Treats moderate to severe pain. It is also used to treat narcotic addiction in patients who cannot take oral medicines.

Brand Name(s):

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to methadone, or if you have lung disease, trouble breathing, or if you are having an asthma attack.

How to Use This Medicine:


  • A nurse or other health provider will give you this medicine.
  • Your doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot under your skin, into a muscle, or into a vein.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are using naloxone, naltrexone, medicine to treat HIV or AIDS (such as nevirapine, efavirenz, ritonavir, lopinavir, zidovudine, didanosine, or stavudine), medicine to treat fungal infection (such as ketoconazole, clotrimazole, Nizoral®), rifampin, phenytoin, phenobarbital, carbamazepine, or St. John's Wort. Also tell your doctor if you are using a monoamine (MAO) inhibitor (such as Eldepryl®, Marplan®, Nardil®, or Parnate®) or have used one within the past 14 days.
  • Tell your doctor if you are taking medicine to treat bacterial infection (such as erythromycin, clarithromycin, Biaxin®, Ery-tab®), medicine for heart rhythm problems (such as quinidine, disopyramide, amiodarone, Norpace®, Cordarone®), medicine to treat mental illness (such as haloperidol, prochlorperazine, Haldol®, Mellaril®), blood pressure medicine (such as diltiazem, nifedipine, verapamil, Lotrel®, Norvasc®), or medicine to treat depression (such as sertraline, fluvoxamine, amitriptyline, desipramine, Zoloft®, Prozac®). Also tell your doctor if you are using diuretics ("water pills" such as hydrochlorothiazide (HCTZ), furosemide, Demadex®, Lasix®), laxatives (stool softeners), or hormone medicines.
  • Tell your doctor if you are using any medicines that make you sleepy. These include sleeping pills, cold and allergy medicine, narcotic pain relievers (such as pentazocine, nalbuphine, butorphanol, buprenorphine), sedatives, and certain illegal ("street") drugs.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have heart disease, breathing problems, head injury, liver disease, kidney disease, stomach problems (such as severe stomach pain), low blood pressure, thyroid problems, Addison's disease, prostate problems, or trouble urinating. Tell your doctor if you also have a history of heart rhythm problems such as QT prolongation.
  • This medicine can be habit-forming. Do not use more than your prescribed dose. Call your doctor if you think your medicine is not working.
  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert. Change your positions slowly when getting up from a lying or sitting position.
  • This medicine may cause constipation, especially with long-term use. Ask your doctor if you should use a laxative to prevent and treat constipation.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Decrease in how much or how often you urinate.
  • Dry mouth, increased thirst, muscle cramps.
  • Fainting.
  • Pain, itching, burning, swelling, or a lump under your skin where the needle is placed.
  • Seizures.
  • Slow, fast, pounding, or uneven heartbeat.
  • Swelling in your hands, ankles, or feet.
  • Trouble breathing.
  • Unusual bleeding, bruising, or weakness.

If you notice these less serious side effects, talk with your doctor:

  • Changes in menses.
  • Changes in vision.
  • Headache or confusion.
  • Increased sweating.
  • Lightheadedness, dizziness.
  • Loss of appetite.
  • Mood changes, agitation, or trouble sleeping.
  • Nausea, vomiting, constipation, or stomach pain.
  • Problems having sex.
  • Skin rash or itching.
  • Weight gain.
  • Warmth or redness in your face, neck, arms, or upper chest.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 7/4/2018
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