What is methadone?

Methadone is a prescription drug. It’s an opioid, which makes it a controlled substance. That means its use will be closely monitored by your doctor.

Methadone oral tablet is used to manage moderate to severe pain. It’s only given when other short-term or non-opioid pain drugs don’t work for you or if you can’t tolerate them.

Methadone is also used to manage drug addiction. If you’re addicted to another opioid, your doctor may give you methadone to prevent you from having severe withdrawal symptoms.

Methadone side effects

Methadone oral tablet can cause extreme drowsiness and slowed breathing. This is more likely to occur during the first few hours after you take it and when your doctor increases your dosage.

More common side effects

The more common side effects of methadone can include:

  • constipation
  • nausea
  • sleepiness
  • vomiting
  • tiredness
  • headache
  • dizziness
  • stomach pain

If these effects are mild, they may go away within a few days or a couple of weeks.

Serious side effects

  • Respiratory failure (not being able to breathe). Symptoms can include:
    • shortness of breath
    • chest pain
    • feeling faint
    • slowed breathing
    • very shallow breathing (little chest movement with breathing)
    • dizziness
    • confusion
  •  low blood pressure when getting up after sitting or lying down. Symptoms can include:
    • low blood pressure
    • dizziness or lightheadedness
    • fainting
  • Physical dependence and withdrawal when stopping the drug. Symptoms can include:
    • irritability or anxiousness
    • trouble sleeping
    • increased blood pressure
    • fast breathing rate
    • fast heart rate
    • teary eyes
    • runny nose
    • yawning
    • nausea, vomiting, and a loss of appetite
    • diarrhea and stomach cramps
    • sweating
    • chills
    • muscle aches and backache

Do not take these drugs with methadone.

  • Pentazocine, nalbuphine, butorphanol, and buprenorphine. These drugs may reduce methadone’s pain-relieving effects.
  • Taking methadone with certain medications raises your risk of side effects from methadone
    • Cimetidine.
    • Antibiotics, such as clarithromycin and erythromycin.
    • Antifungal drugs, such as ketoconazole, posaconazole, and voriconazole..
    • HIV drugs, such as ritonavir or indinavir


Taking methadone with certain medications raises your risk of side effects. This is because methadone and these other medications can cause the same side effects. As a result, these side effects can be increased. Examples of these drugs include:

    • Allergy drugs, such as diphenhydramine and hydroxyzine
    • Urinary incontinence drugs, such as tolterodine and oxybutynin.
    • Benztropine and amitriptyline.
    • Antipsychotics, such as clozapine and olanzapine.
    • Heart rhythm drugs, such as, quinidine, amiodarone, and dofetilide
    • Amitriptyline



  • Form: oral tablet
  • Strengths: 5 mg, 20mg,40mg
  • Form: oral solution
  • Strengths: 25mg/5ml

±The safety and effectiveness of this drug hasn’t been established in children. It shouldn’t be used in children younger than 18 years.