Methadone is an opioid medication used to treat chronic pain. It has also been used in the treatment of opioid addiction since the 1950s. Methadone may be given during drug detox to lessen painful withdrawal symptoms or prescribed as part of an opioid treatment program. When methadone is used as a long-term maintenance medication for opioid use disorder, it is known as opioid replacement therapy or methadone maintenance treatment (MMT).  

How is Methadone Used in the Treatment of Opioid Addiction?

Methadone acts as an opioid substitute in people experiencing opioid use disorder (OUD). As a long-acting opioid agonist, methadone does not produce the powerful high of drugs like heroin, morphine or prescription opioids. However, because it acts on the same receptors in the brain as short-acting opioids, it can ease the symptoms of narcotic withdrawal, blunt the euphoric effects of opioid drugs, and decrease opioid cravings 1. These effects make it useful in both medication-assisted detox and the ongoing treatment of opioid use disorder.

Methadone maintenance treatment (MMT) can last for a few months to a year or for several years, depending on the severity of a person’s addiction and their level of success while taking prescribed methadone. 

Like other prescription medications, methadone serves many purposes, but it also has the potential to produce a range of side effects. There is also a risk of methadone overdose if the medication is not taken as directed by a physician. 

Here’s what you should know about the risks and side effects of methadone. 

Common Methadone Side Effects

The most common side effects of methadone are typically mild and go away after a period of use. However, they should be reported to a doctor if they get worse or persist for a long period.

These side effects include: 

  • Headache
  • Nausea
  • Dry mouth
  • Restlessness
  • Itchiness
  • Increased perspiration
  • Slowed bowel activity 
  • Slowed breathing

Serious Potential Side Effects of Methadone Use

There are a handful of potentially serious side effects associated with methadone use. While these side effects are rare, they can be life-threatening, so it’s important for any person regularly using methadone to understand the associated risks and how to identify them. 

Serious potential side effects of methadone include: 

  • Severe allergic reaction: skin rash, hives, swelling of the face, tongue or throat, or trouble breathing
  • Dizziness and fainting
  • Sleep problems
  • Slow heart rate
  • Seizures
  • Severe drowsiness
  • QT prolongation (especially concerning for people with a family history of long QT syndrome)
  • Psychiatric disturbances, including hallucinations and mood changes
  • Sexual dysfunction
  • Difficulting urinating

It is critical for anyone taking methadone or considering a methadone treatment program to discuss potential side effects with their doctor. 

Can Methadone Cause Withdrawal Symptoms?

When taken as directed by a medical professional, methadone is a safe and effective medication. Misuse of methadone, including taking more or less than the recommended dosage, carries a risk of uncomfortable and potentially dangerous consequences. 

Taking more than the recommended dose of methadone can result in a methadone overdose, which is a life-threatening health event that requires immediate medical attention. Taking less than the prescribed amount, especially after a long period of regular use, can result in withdrawal symptoms. 

Methadone withdrawal symptoms include: 

  • Chills
  • Sweating
  • Muscle aches and pains
  • Anxiety
  • Nausea and vomiting
  • Stomach cramps and gastrointestinal problems
  • Insomnia 
  • Rapid heartbeat

Quitting methadone cold turkey is more likely to produce withdrawal symptoms than slowly tapering usage. Individuals who want to stop taking methadone to treat their opioid use disorder should always talk to their doctor before discontinuing their dosage. 

Opioid substitutes like methadone and buprenorphine are a critical part of treatment for many people experiencing opioid addiction. But they should only be used at the direction of a medical provider as part of a wider addiction treatment program. Methadone and other opioid substitutes like buprenorphine carry a risk of addiction if abused recreationally.

Treatment for Opioid Addiction at STR Behavioral Health

STR Behavioral Health in Pennsylvania provides medication-assisted detox and residential treatment for opioid addiction. If you’re suffering from opioid use disorder, the first step to recovery is safe detoxification and addiction treatment in a compassionate environment, one where you can develop the coping mechanisms and life skills necessary for long-term freedom from addiction. 

Find an STR location today to take the first step in overcoming opioid addiction. 


  1. Dydyk, Alexander M., et al. “Opioid Use Disorder.” PubMed, StatPearls Publishing, 17 Jan. 2024,
  2. Karki, Pramila, et al. “The Impact of Methadone Maintenance Treatment on HIV Risk Behaviors among High-Risk Injection Drug Users: A Systematic Review.” Evidence-Based Medicine & Public Health, vol. 2, 2016, p. e1229,