Methadone Side Effects | What Are The Side Effects Of Methadone?

Medically Reviewed by Johnelle Smith, M.D. on December 28, 2021

Methadone is a prescription painkiller and addiction medication used for the treatment of opioid use disorder. Use of methadone can cause a range of side effects. Side effects of methadone may be effectively managed with medical and behavioral health interventions.

Side Effects Of Methadone

Methadone is a central nervous system (CNS) depressant. Although it can effectively relieve pain and blunt opioid cravings, other physical and mental side effects can occur.

If you or a loved one is taking methadone for addiction treatment, you can find information here about the side effects of methadone and how to find methadone treatment options near you.

Learn more about using methadone during medication-assisted treatment.

Short-Term Side Effects Of Methadone

Methadone is generally taken in a single daily dose. Side effects on the body, cognition, and mood can occur as a result of how methadone interacts with the brain and nervous system.

Short-term side effects of methadone may include:

  • drowsiness
  • relaxation
  • dry mouth
  • nausea and vomiting
  • constipation
  • restlessness
  • feeling of heaviness in the arms, legs, hands, and feet
  • difficulty falling or staying asleep
  • flushed skin
  • itchiness
  • slow breathing
  • sexual problems

Methadone is a long-acting drug, meaning its effects may occur in phases over the course of a day. Some side effects may last for hours, while others may fade more quickly.

Serious Side Effects Of Methadone

Although uncommon, some serious side effects of methadone can occur. If you or someone you know is experiencing serious side effects after taking methadone, call your doctor right away.

Serious side effects that can occur while taking methadone:

  • feeling very faint or weak
  • difficulty breathing or very slow breathing
  • seizures
  • hives or rash
  • severe itching
  • swelling of the nose, face, mouth, or tongue
  • fast or pounding heartbeat
  • chest pain
  • hallucinations (seeing or hearing things that aren’t there)
  • confusion

Serious side effects may indicate an allergic reaction or an unsuitable dosage of methadone for safe treatment purposes.

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Long-Term Side Effects Of Methadone

Methadone is a drug that can be taken long-term for opioid dependence and chronic pain. Chronic use of methadone, however, can result in certain physical and cognitive side effects.

Long-term side effects of methadone use might include:

  • physical dependence
  • insomnia
  • changes in mood
  • withdrawal (with stopped use)

Developing A Methadone Dependence

Chronic methadone use can result in physical dependence. This can cause the body to go through withdrawal if a person misses a dose, or goes 24 to 36 hours without taking more methadone.

Undergoing Methadone Withdrawal

Withdrawal syndrome is a set of physical and psychological symptoms that can occur if someone who is dependent on methadone tries to stop taking the drug too quickly or all at once.

Getting off methadone may require an opioid detox program. This can provide medical and behavioral support to help treat methadone withdrawal symptoms.

Factors That Can Affect Methadone Side Effects

No two people react to drugs like methadone in the same way. A variety of factors can influence how a person’s mind and body reacts to methadone.

What factors might influence methadone side effects:

  • dose taken
  • drug tolerance
  • use of other drugs (including alcohol)
  • body mass
  • metabolic rate
  • formulation taken
  • route of administration
  • mental health conditions
  • liver and kidney function

Serious side effects can occur in some people. If you or a family member is experiencing severe side effects from taking methadone, contact your doctor.

Methadone Side Effects FAQs

Having questions about the side effects of methadone is common. Here are answers to some of the most frequently asked questions about methadone side effects.

Euphoria does not generally occur in people who are taking a treatment dose of methadone for opioid use disorder. Mild euphoric effects, such as a positive sense of well-being, may occur.

Itching is a common side effect of opioid drugs. Severe itching, however, can be a sign of an adverse reaction or a drug allergy.

Read more about itching from taking methadone.

Depression is a common co-occurring disorder in people who receive methadone for drug addiction. But it is unlikely to occur as a result of methadone use.

Read more about depression as a result of taking methadone.

Decreased blood pressure is a potential side effect of methadone. An increase in blood pressure from methadone is uncommon but can occur under certain circumstances.

Read more about how methadone can affect blood pressure.

Methadone does have common side effects that can lead to minor or temporary weight gain in some people, including constipation, fatigue, changes in metabolism, and water retention.

Read more about gaining weight from taking methadone.

Cardiac effects, or heart problems, have been documented in some people who take methadone.

Taking very high doses of methadone or taking multiple doses a day for pain may increase the risk of experiencing heart problems while taking methadone.

Read more about how methadone can affect the heart.

Methadone can have a range of physical side effects. In some people, methadone may cause intestinal problems, affect the skin, and cause swelling of the legs.

Read more about how methadone affects the body.

Call Today To Learn More About Methadone Treatment

For decades, methadone has been used as a leading treatment for heroin addiction and opioid use disorder, which can be life-threatening without treatment.

For more information about methadone maintenance treatment, call our helpline today to speak to one of our trained staff members about finding methadone treatment options near you.

This page does not provide medical advice. See more

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Medically Reviewed by
Johnelle Smith, M.D. on December 28, 2021
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