Methadone Abuse: Side Effects, Signs, & Symptoms

With methadone and one of the reasons it’s used as a treatment option for the withdrawal symptoms related to other drugs, the person taking it can often function normally and go about their daily life, particularly if they’re taking the dosages prescribed by their health care provider. If there are symptoms of abuse, many of the signs of methadone abuse are similar to what’s seen with other opiates and may include weakness, nausea, vomiting, and trouble sleeping. Signs of methadone use and abuse may also include weight gain and unusual mood patterns. There may also be indications of confusion and dizziness, particularly if someone takes too much methadone.
Largely because of the long half-life of methadone, it may be harder to see immediate signs that someone has taken it, particularly if they’re taking a recommended dose. Methadone has a 22-hour half-life, which is why the high that comes with methadone isn’t as potent as other drugs, such as heroine.

When used as part of methadone maintenance therapy, it can be particularly unusual to see physical indicators, because it’s being administered under the supervision of a health care provider. However, even when someone is taking a prescribed dosage of methadone, there can be some physical symptoms that come with its use.

When someone initially takes methadone, symptoms like the ones listed below can be particularly present. With the first exposure to methadone, most people experience dizziness, and this is the time when someone is likely to feel the most powerful high unless they then start taking higher doses to continue that feeling.

These symptoms often depend on the individual and how much is taken, and can include:

  • Nausea
  • Vomiting
  • Sweating
  • Constricted pupils
  • Slowed breathing
  • Constipation
  • Confusion
  • Drowsiness

In small doses, a person taking methadone may still be able to function normally in their day-to-day life, but if they start taking higher doses in response to a building tolerance, this can change, and they can seem sluggish or unable to do things like driving a car or operating machinery.

As with so many other opiates, a person who takes methadone may start putting so much of their focus on obtaining the drug, including from sources outside of their doctor or health care provider, that they lose interest in other areas of their lives, including relationships.

If someone starts to experience withdrawal symptoms from methadone, it can include yawning, restlessness, sweating and general achiness. There can also be gastrointestinal issues, including vomiting and cramps. With methadone, as opposed to something like heroin, withdrawal symptoms can take days to appear, but they may also last longer.

Regarding behavioral signs of methadone use, often as a person begins to develop a tolerance for the opioid, they will become increasingly focused on trying to get more. There may be attempts to get multiple prescriptions from different health care providers, and there may be a tendency to start taking higher doses of methadone. When it seems as if someone is putting obtaining and taking methadone at the top of their priority list, over work, family and social commitments, it’s often a sign of addiction.

The first time someone takes methadone, whether prescribed by a health care provider or otherwise, they will often feel an immediate sense of dizziness that can sometimes by accompanied by feelings of nausea or confusion.

Other common physical methadone side effects include:

  • Weakness
  • Headache
  • Gastrointestinal problems including constipation, nausea, and vomiting
  • Weight gain
  • Loss of appetite
  • Sore tongue
  • Dry mouth
  • Flushing
  • Sweating
  • Vision problems
  • Problems urinating
  • Sexual problems
  • Missed menstrual periods
  • Problems falling or staying asleep
  • Slower reflexes
  • Clamminess
  • Trouble concentrating
  • Weak muscles

Some of the physical symptoms are the very reason people use methadone. While the high may not be as powerful as with other opioids, it can still lead to an altered sense of perception, light-headiness, and sedation that users may find appealing.

There can also be severe methadone side effects. Some of the more serious methadone effects on the body can include:

  • Seizures
  • Itching, hives or rash
  • Rapid heartbeat
  • Nervousness
  • Restlessness
  • Difficulty swallowing
  • Difficulty breathing
  • Feeling very drowsy
  • Fainting
  • Hallucinations
  • Swelling of the mouth including the tongue and throat
  • Swelling of the face and eyes
methadone abuse
According to the reports from the National Highway Traffic Safety Administration, for most people who use methadone as a way to recover from opiate addiction, there isn’t necessarily the risk of long-term adverse physical effects.

Despite that assertion, the University of Maryland finds that long-term use of methadone can lead to chronic lung and breathing problems since it does so heavily impact the central nervous and respiratory systems.

As with other opioids, people who take methadone may experience a reduction in testosterone, which holds true for men and women. This means that women who take methadone for prolonged periods may have issues with their menstrual cycle, or may stop having it altogether.

The National Cancer Institute reports that long-term methadone effects on the brain and the body can include a reduction in sexual desire and sexual dysfunction. Again, this holds true for both men and women.

As with other opioids, methadone impacts certain brain processes and structures. Long-term methadone effects on the brain may include changes in cognitive functioning, problems with memory, and learning difficulties.

Methadone effects on the brain with long-term use may also include changes in mood and behavior, and neurotransmitters may be impacted.

Specific methadone effects on the brain may include not only sedation and depressed reflexes but also confusion, agitation, and restlessness. It can increase levels of serotonin, which can have an effect on the brain over the long-term, and in general methadone effects on the brain can lead to a higher risk of developing psychiatric disorders.

Chronic use of methadone has been shown to contribute to problems related to overall health status, as well as relationships and social interactions, and financial problems.

Much as is the case with the use of other opioids, methadone side effects on teeth may also be present. Methadone side effects on teeth aren’t often as pronounced as what’s seen with methamphetamines, but it can contribute to some tooth decay. The reason methadone side effects on teeth are present is because it can cause dry mouth, which increases the presence of bacteria and plaque in the mouth.

The answer is yes you can, and it’s actually relatively common. People also often wonder how much methadone does it take to overdose.

To answer the question of can you overdose on methadone, consider the following:

  • Methadone can occur accidentally or intentionally, and you can also overdose on methadone if you take it with other painkillers such as oxycontin, morphine or hydrocodone.
  • Since methadone doesn’t cause the powerful rush of euphoria from other drugs but is relatively inexpensive, people who are addicted to other drugs may overdose inadvertently trying to achieve a high.
  • One of the other most common reasons people overdose on methadone is because a person may develop a tolerance very quickly to this drug, and as a result take larger and larger quantities.

The question of how much methadone does it take to overdose can be a complicated one. Officially the lethal dose for an adult who isn’t tolerant to methadone is 25 mg., but for someone who uses methadone regularly, the fatal dose may be 200 mg.

One of the biggest risk factors that determine the answer to “can you overdose on methadone,” is how often you take it. Since methadone has a long half-life, people may take more thinking the drug is out of their system, but it may still be present in their body.

Methadone is an especially risky drug because it builds up in the system, and taking even a prescribed dosage could lead to overdose as a result.

It may take up to 10 hours for symptoms of a methadone overdose to begin appearing.

It’s also important to note that methadone is estimated to be responsible for more than 30% of all overdose deaths from prescription painkillers. Up to 4 out of 10 overdose deaths from prescription painkillers are believed to involved methadone.


Medical Disclaimer: The Recovery Village aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.

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