Methadone Side Effects


Adding any new chemical to your body is sure to cause some changes, and methadone is no exception. Because methadone is itself an opioid agonist, you can be sure that it will cause some of the same side effects that any opioid would. However, it is a weak opioid and will not give you euphoria that would ensue from illicit drugs. Instead, you will probably feel the most side effects within an hour or two of taking methadone.

Initial Side Effects

You may notice some side effects as soon as you take your first dose. These could include the following:

  • Nausea and vomiting
  • Slower breathing
  • Dry mouth
  • Tiredness
  • Anxiety
  • Restlessness
  • Weakness
  • Dizziness
  • Confusion
  • Poor coordination


Over time, these symptoms should taper off once the methadone levels stabilize. While these side effects are common, they are perceived as less prevalent.

Side Effects from Long-Term Use

While you will probably be on methadone for a minimum of twelve months, life-long treatment should not be expected. Continuous methadone administration may result in irreversible organ damage and hasten respiratory issues.

Side Effects from High Dosages

Overdosing of methadone may result in buildup and dysfunctional excretion from the body. A physician should be informed of noticeable symptoms and adverse side-effects, as further medical intervention may need to be addressed. 

  • Blue-tinged skin
  • Very shallow, slow breathing
  • Inability to stay awake
  • Heavy vomiting
  • Convulsions

Side Effects from Methadone Withdrawal

Once methadone treatment has reached termination, a physician will gradually taper off the drug rather than eliminating the drug immediately. Terminating  too quickly may result in several side effects, such as the following:

  • Fever and chills
  • Muscle and joint aches
  • Fast heartbeat
  • Diarrhea
  • Insomnia
  • Anxiety and depression
  • Hallucinations
  • Stomach pain

The patient-provider relationship is crucial, as it aids proper communication regarding treatment. While some side effects are to be expected with methadone usage, you should not be feeling terribly uncomfortable during treatment. If you are experiencing new, concerning, or serious side effects, be sure to contact the prescribing physician immediately. He or she will be able to prescribe a dosage that will achieve a patient’s individual needs.

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