Side Effects of Methadone Treatment

Methadone is an opioid addiction and dependence medication that is often taken on an ongoing basis as a part of a medication-assisted treatment plan or as methadone maintenance. If you are considering taking this medication, it’s important to know potential methadone side effects, how to manage them, and contraindications for use.

What is Methadone Treatment?

Methadone is a medication approved by the Federal Drug Administration (FDA) to treat opioid use disorder (OUD). Providers have been using it to treat OUD since 1947, making it the longest-running and most widely used OUD treatment.1,2

Researchers have found that methadone reduces opioid use among patients. They also found that patients taking methadone were more than four times more likely to stay in treatment for OUD.1

Methadone is itself an opioid; however, it is long-acting and doesn’t cause an intense euphoric rush like opioids of abuse like heroin or fentanyl.3 Methadone is a safe and effective medication if you take it as prescribed by your methadone provider.1

What are the Potential Side Effects of Methadone Treatment?

As with any medication, there are possible side effects of methadone, both minor and severe. Some include methadone side effects on the stomach, which can range from mild to severe.

Common Methadone Side Effects

There are some common, relatively mild side effects of methadone. If any of the following side effects are severe or do not go away, tell your doctor:3,4

  • Stomachache
  • Dry mouth and sore tongue
  • Flushing that may result in red patches on your skin and feelings of warmth around the neck, upper chest, or face
  • Difficulty urinating
  • Headache
  • Weight gain
  • Mood swings
  • Vision issues
  • Sleep disturbances

Severe Side Effects

Some methadone side effects may be severe and extremely distressing. Get medical attention right away if you experience the following:3,5,6

  • Seizures
  • Swelling of the eyes, face, mouth, tongue, or throat
  • Itching, rash, or hives
  • Difficulty breathing
  • Difficulty swallowing
  • Severe drowsiness
  • Agitation
  • Hallucinations
  • Fever
  • Extreme sweating
  • Confusion
  • Rapid heart rate
  • Shivering
  • Profound muscle stiffness
  • Coordination difficulties
  • Nausea, vomiting, or diarrhea
  • Weakness or dizziness
  • Erectile dysfunction
  • Irregular menstruation
  • Slow and ineffective breathing
  • Perforation of peptic ulcer

If you have peptic ulcer disease and suddenly stop taking methadone on your own without consulting your prescriber, you risk developing a perforation or hole in your stomach. A perforation is a severe complication of peptic ulcer disease.7

One study was conducted with 35 patients admitted for perforations. All patients had a history of opioid addiction and a history of ulcers. The researchers found that all perforations occurred right after abrupt cessation of long-term opioid use.5

Therefore, if you have a history of ulcers and suddenly stop taking methadone, there is a chance that you could develop perforations in your stomach and should not stop taking it without your provider’s guidance.1

If you are unable to tolerate the methadone side effects, call your doctor to discuss possible adjustments to your dosage and schedule.

Risk for Overdose

Because methadone is an opioid, there is a chance an overdose can occur. However, this is unlikely if you take your medication exactly as prescribed and don’t mix it with other substances or misuse it. Still, it’s always important to know the signs and symptoms of a methadone overdose, which include:3

  • Very small pupils
  • Slow or shallow breathing
  • Difficulty breathing
  • Extreme drowsiness
  • Cool, clammy, or blue skin
  • Inability to respond or wake up
  • Limp muscles

If you experience any of these symptoms, it is important to call 911 right away.

Given the small chance of an overdose, it is imperative to take methadone only as prescribed by your provider. Do not change your dose or stop taking the medication without consulting with your provider.3

In addition, talk with your provider about having a naloxone at your home or to carry with you. Naloxone is a life-saving medication that rapidly reverses the effects of an opioid overdose. If you suspect you have overdosed on methadone, take naloxone and call 911. It’s also a good idea to teach your loved ones how to recognize a methadone overdose and administer naloxone as well.3

How are Methadone Side Effects Managed?

Though the prospect of experiencing methadone side effects can be overwhelming, the good news is that providers have a few strategies for managing them: dose reduction, opioid rotation, changing the method of administration, and medications for specific symptoms.4,8

Dose Reduction

Your provider may reduce your dose of methadone, which could help with side effects like drowsiness and confusion. Scientists recommend this method as the first approach for providers to take. Providers work to find an optimal dose where the side effects are minimized while you still get the benefits of the medication: reduced cravings and opioid withdrawal symptoms.8

The optimal dose can vary from person to person, so experts recommend starting at a low dose and slowly increasing as needed.8

Medication Rotation

Your provider may change the medication they prescribe you for treating your opioid use disorder (OUD). This can help with side effects such as nausea and vomiting.8 Other possible medication treatments for OUD include buprenorphine, naltrexone, and Suboxone (buprenorphine/naloxone).1

Providers carefully consider the best medication for you based on various factors, such as how you responded to opioids in the past, other medical conditions you have, and other medications you are currently taking.8

Change in Method of Administration

Another way you can take methadone is through a skin patch. This route of administration could have a reduced risk of constipation, nausea, and sedation. Other routes of administration available include a sublingual form that you place under your tongue to dissolve and a liquid form that you can swallow.8

Medications for Symptoms

The fourth major method that providers can use to address methadone side effects is by using medication to target specific symptoms.8

Medications can reduce nausea if needed, though nausea tends to be short-lived. To minimize the side effect of constipation, providers may direct you to take laxatives or stool softeners. They may also recommend a high-fiber diet, increasing your fluid intake, and increasing your physical activity.8

The side effect of sedation also tends to be short-lived. If it does persist over time, your provider is likely to review all of the medications you are taking to see if any can be discontinued.8

Lastly, your provider may prescribe antihistamines or topical lotions to treat pruritus or itching.8

When is Methadone Treatment Risky?

If you have certain medical conditions, providers do not advise methadone treatment. With some other medical conditions, prescribers carefully monitor how you respond to methadone and make changes to your treatment plan as needed.5


There are certain populations for whom the safety and effectiveness of methadone has not been established; therefore, providers are not likely to prescribe you methadone if you:5

  • Are below the age of 18
  • Have paralytic ileus or a blocked intestine
  • Have other gastrointestinal obstructions
  • Have chronic obstructive pulmonary disease or other respiratory problems

Careful Use and Monitoring

There are also populations for which it is critical to be cautious when using methadone treatment. This is the case for you if you:5

  • Are over the age of 65
  • Have renal or kidney impairment
  • Have a hepatic or liver impairment
  • Have a brain tumor
  • Have low blood pressure

In these situations, your provider will likely start you at a low dose and closely monitor how methadone affects these conditions.5

Methadone Treatment Gives Hope for Recovery

Methadone treatment is safe and effective if you struggle with opioid use disorder (OUD). It is also safe during pregnancy and for those who also have other mental health disorders. The great thing about methadone is that it can be taken in the long-term, with many people taking it for several years to help maintain abstinence. When combined with counseling and therapy, methadone is even more effective, since your therapist can address underlying issues that motivated opioid use and provide you with useful coping skills to help you manage triggers and stressors.

For assistance with locating methadone treatment programs near you, please call 800-678-5931(Paid Advertiser) 24/7 to get the help you need.


  1. National Institutes of Health. (2021, December). Medications to Treat Opioid Use Disorder Research Report. National Institute on Drug Abuse.
  2. Rosic, T., Naji, L., Bawor, M., Dennis, B.B., Plater, C., Marsh, D.C., Thabane, L., & Samaan, Z. (2017). The Impact of Co-morbid Psychiatric Disorders on Methadone Maintenance Treatment in Opioid Use Disorder: A Prospective Cohort Study. Neuropsychiatric Disease and Treatment, 13, 1399-1408.
  3. U.S. National Library of Medicine. (2022). Methadone. MedlinePlus.
  4. Schlienz, N.J., Huhn, A.S., Speed, T.J., Sweeney, M.M., & Antoine, D.G. (2018). Double Jeopardy: A Review of Weight Gain and Weight Management Strategies for Psychotropic Medication Prescribing During Methadone Maintenance Treatment. International Review of Psychiatry, 30(5), 147-154.
  5. Federal Drug Administration. (2014). Full Prescribing Information.
  6. Kahrom, M., & Kahrom, H. (2010). Perforation of Peptic Ulcer Following Abrupt Cessation of Long-term Opiate Use. Surgery Today, 40, 836-839.
  7. Office of the Legislative Auditor General State of Utah. (2020, December). A Performance Audit of Methadone Clinic Oversight.
  8. Rogers, E., Mehta, S. Shengelia, R., & Reid, M.C. (2013). Four Strategies for Managing Opioid-Induced Side Effects in Older Adults. Clinics in Geriatric Medicine, 21(4), 1-14.

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