Methadone Overdose

Methadone Overdose

Methadone Overdose

Methadone OverdoseMethadone is an opioid (narcotic) medication largely known for its use in withdrawal from heroin and other opioid drugs of abuse. In people without opioid addictions, doctors increasingly use the medication as a treatment for moderate to severe pain that doesn’t respond to more basic, non-opioid options. While methadone prescriptions make up only 2 percent of all opioid painkiller prescriptions written in the US, roughly one-third of all people who die from an opioid painkiller overdose are methadone users. Underlying reasons for this fact include methadone’s effects on the central nervous system and the way in which the medication accumulates in the body over time.

Methadone Basics

Methadone is a synthetic opioid drug designed to mimic the basic effects of naturally occurring opioids such as opium and codeine, which come from a plant called the opium poppy (Papaver somniferum). Inside the body, molecules of the drug bind to sites called opioid receptors, which sit on the surface of certain nerve cells located in the central nervous system (brain and spinal cord) and digestive tract (stomach and small intestine). Normally, these sites are accessed by natural opioid-like substances, including endorphins and dynorphins that provide the body with a reduced sensitivity to pain and a euphoric feeling of enhanced well-being.

The presence of opioid drugs also activates the opioid receptors, and typically results in euphoric and pain-relieving effects far beyond those produced by endorphins, dynorphins or other similar internal substances. Like other opioids, methadone provides significant amounts of pain relief; however, compared to classic opioid drugs of abuse, it produces a limited amount of euphoria. When given to people addicted to other opioids, it can help prevent withdrawal symptoms by acting as an intermediate step between unchecked addiction and drug abstinence. When given to people with symptoms of moderate to severe pain, it can provide much more relief than the average non-opioid painkiller.

Setting the Stage

Depending on the individual, methadone can provide pain relief for anywhere from roughly four to eight hours. However, after its pain-relieving potential is exhausted, the drug remains in general circulation for as long as another 50 to 55 hours. In practical terms, this means that methadone can easily accumulate in the body over time; if this accumulation rises to toxic levels, it sets the stage for a drug overdose. Doctors typically limit the risks for an overdose by limiting the number of times their patients can take the drug on any given day. However, not all people follow the guidelines set by their doctors, and some individuals who use methadone for pain relief trigger an overdose when they purposefully or mistakenly take more of the drug than their prescriptions permit.


Like other opioids, methadone reduces the rate of communication between the nerve cells (neurons) in the central nervous system. Below the threshold for overdose, consequences of this nervous system slowdown include a reduction in the normal breathing rate and subtle alterations in the internal electrical timing used to control coordinated beating of the heart. A methadone overdose occurs when too much of the drug builds up in the body and produces an unsupportable degree of central nervous system suppression.

At its worst, such an overdose can result in severe or fatal consequences such as extremely slowed or absent breathing and heartbeat irregularities that trigger a complete stoppage of the heart known as cardiac arrest. The US National Library of Medicine lists additional potential symptoms of a methadone overdose that include abnormally shallow breathing, dizziness, muscle weakness, fatigue, nausea, vomiting, constipation, pupil constriction (narrowing), a weakened pulse, hypotension (low blood pressure), blue coloration in the lips or fingernails, drowsiness, confusion or mental disorientation, spasming in the digestive tract, abnormally clammy or cold skin, loss of consciousness, and entry into the unresponsive state called coma.


In terms of its overdose risks, methadone appears to be roughly twice as dangerous as any other prescription pain-relieving medication, the Centers for Disease Control and Prevention report. Despite this fact, US doctors prescribe the drug as a pain treatment more than four million times each year. Risks for overdose are especially high in people who combine use of methadone with use of other painkillers, or with use of sedative-hypnotic medications (i.e., tranquilizers). In addition to limiting prescriptions of the drug to a maximum of three doses per day, doctors can lower the risks for a methadone overdose by properly screening their patients for other medication/drug use, regularly reviewing their patients’ adherence to prescription guidelines, and educating their patients about the inherent risks of methadone use and misuse.

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