What Is A Lethal Dose Of Methadone?

Medically Reviewed by Johnelle Smith, M.D. on July 13, 2021

Methadone is a synthetic opioid agonist that is used to treat pain, opioid use disorder, and heroin addiction. The lethal dose of methadone is a dose high enough to cause death, which can occur after taking excessive amounts of methadone alone or with other drugs.

What Is The Lethal Dose Of Methadone?

The lethal dose of methadone is a dose of methadone that is high enough to have fatal consequences. A lethal dose is much higher than any dose prescribed by a doctor.

Methadone is prescribed for:

  • pain relief
  • opioid dependence
  • heroin addiction

Methadone can be safe and effective when taken as prescribed. Taking methadone in any way other than prescribed can risk serious health consequences, including fatal overdose.

Learn more about the lethal dose of commonly abused drugs

Determining A Lethal Dose Of Methadone

Methadone is a strong painkiller often used to treat opioid dependence and addiction. The lethal dose of methadone can vary depending on a person’s age and opioid tolerance.

Estimated lethal doses of methadone include:

  • For children: as low as 10 milligrams (mg)
  • For opioid-naive adults: 30 to 50 milligrams
  • For opioid-tolerant adults: >120-200 milligrams

The lethal dose of methadone in someone who is opioid-tolerant or opioid-dependent will be higher than for the average person.

Lethal doses for drugs like methadone can vary. It’s highly recommended that people who are prescribed methadone take it exactly as prescribed to avoid serious side effects.

Causes Of Fatal Methadone Overdose

Fatal methadone overdose can occur a few ways:

  • taking very high doses
  • taking multiple doses too close together
  • taking high doses of methadone with other drugs
  • imprecise conversion while transitioning to methadone from another opioid

Methadone can be toxic in high doses. Drinking alcohol while taking methadone, or taking it with other drugs not prescribed by a doctor, can increase the risk of fatal overdose.

Factors That Can Affect The Lethal Dose Of Methadone

Various factors can affect how much methadone it takes for it to have fatal consequences. These factors can vary from one person to the next.

Factors that can affect the lethal dose include:

  • age
  • opioid tolerance
  • method of use
  • drug metabolism
  • ingestion of multiple drugs (e.g. benzodiazepines)
  • impaired kidney and liver function

Recognizing The Signs Of A Methadone Overdose

Methadone overdose can be deadly. Knowing the signs of methadone overdose can be life-saving.

Signs of a methadone overdose include:

  • difficulty breathing
  • slow or no breathing
  • very tiny pupils
  • limp body
  • cold, clammy skin
  • blue fingernails and lips
  • nausea and vomiting
  • weak pulse
  • low blood pressure
  • unable to talk
  • unconsciousness

Methadone overdose can be reversible with prompt treatment. Naloxone, or Narcan, is an opioid overdose treatment that can reverse methadone overdose by blocking its effects in the brain.

How Common Is Fatal Methadone Overdose?

According to data from the National Center for Health Statistics, 2,740 drug overdose deaths in the United States in 2019 involved methadone.

Methadone is less likely to cause overdose compared to other opioids such as fentanyl, heroin, and other prescription opioids.

Although it acts on the same opioid receptors as these other drugs, it activates them more slowly, which reduces its addictive potential and overdose risk.

Finding Treatment For Methadone Abuse And Addiction

Methadone overdose can be a sign of methadone abuse and addiction. If you or a loved one is misusing methadone, we can help you find a treatment program that’s right for you.

Call our helpline today to learn more about methadone abuse and addiction treatment options.

This page does not provide medical advice. See more

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Medically Reviewed by
Johnelle Smith, M.D. on July 13, 2021

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