Methadone Side Effects

Methadone is a synthetic opioid medication that acts on various receptors in the brain. These actions are responsible for methadone's analgesic or pain-relieving effects, euphoric or pleasureful effects, as well as unwanted side effects like constipation, sedation, and shallow breathing.15

What is Methadone Used For?

Methadone is one of several approved medications by the Food and Drug Administration (FDA) to treat opioid use disorder (OUD). These medications, as part of a comprehensive treatment plan, are referred to as medication-assisted treatment (MAT).12 MAT is supported by the scientific community as a way of successfully treating opioid addiction and, in addition to medications like methadone, involve supervised detoxification, treatment planning, and counseling.12

While medications like methadone are not considered stand-alone treatments, they are encouraged because they lower the risk of relapse. Methadone does this by reducing opioid cravings and withdrawal while also blocking the effects of other opioids.12

Methadone, by law, can only be dispensed by a certified opioid treatment program (OTP) and under the supervision of a practitioner.12 You may be permitted to take methadone at home between visits if you display an appropriate level of stability with your medication regimen.12 The length of time you receive methadone varies widely from person to person—some may require long-term methadone maintenance while others may take it for shorter periods.

Whether receiving longer or shorter-term treatment, coming off methadone should only be done gradually and under the supervision and guidance of a physician.16 Abruptly stopping methadone can result in withdrawal symptoms and put you at increased risk for relapse and overdose.14

If you're seeking treatment for opioid addiction and want to learn more about methadone, call 800-785-6890 to discuss your options.

Short-Term Effects of Methadone Use

Methadone has greater bioavailability and a uniquely longer half-life than other opioids like morphine11 which means it's easily absorbed by your body but is released slower than other opioids. Because methadone is released more slowly into the bloodstream, it's rewarding effects are weaker than faster-acting opioids like morphine and heroin, but it also means methadone can be taken once a day.7 For these reasons, Methadone is an ideal candidate for treating opioid use disorder (as well as pain).

The primary effects you can expect when taking methadone depend (in part) on the reason it is being prescribed. When prescribed as an analgesic or pain reliever, you should experience pain relief. When prescribed as a treatment for opioid addiction, you should experience a reduction in cravings for opioids and/or alleviation of withdrawal symptoms.

In addition to these treatment effects, methadone may result in some unwanted side effects, such as:16

  • Headache
  • Weight gain
  • Stomach pain
  • Dry mouth
  • Flushing
  • Difficulty urinating
  • Mood changes
  • Inability to keep an erection
  • Decreased sexual desire

Some short-term side effects from methadone may be more severe and include:

  • An allergic reaction such as itching, hives, rash, and/or swelling of the eyes, face, mouth, tongue, or throat
  • Extreme drowsiness
  • Seizures
  • Difficulty breathing or swallowing
  • Agitation
  • Hallucinations
  • Fever
  • Sweating
  • Confusion
  • Severe muscle stiffness or twitching
  • Loss of coordination
  • Nausea
  • Vomiting or diarrhea

Long-Term Effects: What to Expect When Taking Methadone

When taken as prescribed and under the supervision of a physician, long-term use of Methadone is safe.12 This can change, however, if it's used illicitly or if prescribers are not aware of other medicines that dangerously interact with the drug.11 Not much is known about the effects of long-term Methadone abuse, however, when looking at long-term opioid abuse, more generally, recent research has found associations with structural damage in the brain10 as well as some memory problems.13 This is not to mention the potential damage to your relationships and ability to work if abuse turns into an addiction.

Psychiatric disturbance is also commonly seen in many substance use disorders, including opioid use disorder. In one study, nearly half of subjects with opioid use disorder had a co-occurring anxiety or mood disorder (e.g., depression or bipolar)5 with depression, post-traumatic stress disorder, and some anxiety disorders being especially common.1 Major depression can also be a risk factor for future opioid abuse, along with non-related factors like age (younger than 65), gender (male), and past opioid abuse.2

The relationship between psychiatric disorders and opioid use disorders is somewhat unclear. Having a psychiatric disorder can put you at risk for a future opioid use disorder and conversely, using opioids can increase the risk of developing a psychiatric disorder. Genetic conditions can additionally put you at risk for developing both disorders.9

Whatever the risk is, if you have or are at risk of psychiatric disorders, you should avoid illicitly using drugs like opioids. If you're illicitly using opioids, be aware of the potential risk for developing a psychiatric disorder that can complicate treatment beyond your opioid addiction.

Due to the high frequency of psychological disorders in opioid-dependent people, it is highly advised to seek treatment centers that offer psychiatric services like counseling and medication (e.g. antidepressants). Call 800-785-6890 to speak to a treatment advisor and talk about your options.

Methadone Abuse and Addiction

Long-term use of methadone can lead to physical dependence, addiction, or both. Addiction and physical dependence might sound like the same thing, but it's important to distinguish them.14

Physical Dependency on Methadone

Physical dependency is the body's need for a substance to feel normal or avoid withdrawals. Patients taking methadone who only develop a physical dependency are typically those who are prescribed methadone to relieve severe, chronic pain or treat opioid addiction under the supervision of a physician.

Even when methadone administration is supervised and dosages followed properly, you can become physically dependent if methadone is taken for long enough—your body needs methadone to function normally, and when the substance suddenly becomes unavailable, the body goes through withdrawals.

Methadone Addiction

Addiction is more psychological than a physical dependency, and while, at times, it may be difficult to see, there are a few obvious signs that you may be addicted, such as:

  1. Taking methadone to get high
  2. Taking methadone illicitly (i.e., not under physician supervision) and/or in higher doses or frequencies than was prescribed
  3. Taking methadone with other drugs to enhance the effects
  4. Making excuses to consume or obtain more methadone

Also, you may be addicted to methadone if you notice negative effects in your everyday life, such as poor work performance, deteriorating relationships, or the inability to take care of yourself.

While methadone is used to treat opioid addiction, you can abuse or become addicted to it, especially if it is used illicitly. Methadone overdose is linked to illicit use, especially when it is taken with other substances like benzodiazepines (e.g., Xanax) that, like methadone, also slow your breathing and heart rate.14

Methadone Withdrawal Symptoms

Whether or not you're addicted to methadone, you should never stop taking it abruptly as doing so will result in withdrawal symptoms and can increase the risk for relapse and overdose.14

Methadone use can lead to withdrawal symptoms if taken for long enough but can also be prescribed to reduce or alleviate withdrawal symptoms from other opioids. In either case, people generally keep using methadone to avoid withdrawal symptoms, even when they no longer want to use. The severity of methadone withdrawal symptoms will depend on a variety of factors, including the half-life of the opioid, and frequency and duration of use, and your health status.6

Early signs of withdrawal from opioids, including methadone, include:16

  • Agitation
  • Anxiety
  • Muscle aches
  • Insomnia
  • Sweating
  • Yawning

Withdrawal symptoms that may come later include:

  • Abdominal cramping
  • Diarrhea
  • Dilated pupils
  • Nausea
  • Vomiting

If you're thinking about quitting opioids, be aware of the challenging withdrawal symptoms that potentially lie ahead and seek out supervised detoxification rather than attempting to detox at home. Call 800-785-6890 for help with quitting methadone or other opioids safely.

Supervised detoxification is medically monitored to ensure comfort, prevent relapse, and address any physical or psychological complications that arise during withdrawal from opioids. Supervised detoxification may or may not be accompanied by the administration of methadone which decreases the severity of withdrawal symptoms and is associated with lower relapse rates.

Symptoms of a Methadone Overdose

Overdose is a very dangerous risk of methadone use. If taken as prescribed and under the supervision of a physician, methadone is unlikely to cause an overdose. However, if it's taken illicitly (i.e., not as prescribed), especially in combination with other central nervous system depressants (e.g., alcohol, benzodiazepines), the risk of overdose increases.14

Symptoms of overdose from methadone and other opioids include:16

  • Extreme drowsiness or loss of consciousness
  • Slow or shallow breathing
  • Limp muscles
  • Cool, clammy or blue skin
  • Small, pinpoint pupils

If you are allowed to take methadone at home you should be given or be told to have a rescue medication called naloxone available. Naloxone helps to block the effects of opioids and reverse symptoms of overdose. Because individuals who have overdosed are not able to treat themselves, it is important to make sure your friends and family members are aware of naloxone and how to use it in the event of a methadone overdose.16

Is Methadone Safe?

Methadone was initially formulated to relieve pain and is still prescribed for that purpose3 but more commonly, it is prescribed to treat opioid addiction.15 When used as directed by a physician for treating opioid addiction, Methadone is a safe and cost-effective option,12 however, does carry some significant risks, including addiction and overdose.4

Methadone's potency and long duration of action mean that it can build up in the body and have dangerous effects on vital systems like breathing and heart rate.11 It also can interact with other medications or substances that make using either medication alone more dangerous.11 In fact, a significant number of opioid-related deaths in the past 10 years have been linked to Methadone.4


  1. Becker, W. C., Sullivan, L. E., Tetrault, J. M., Desai, R. A., & Fiellin, D. A. (2008). Non-medical use, abuse and dependence on prescription opioids among US adults: psychiatric, medical and substance use correlates. Drug and alcohol dependence, 94(1), 38-47.
  2. Boscarino, J. A., Rukstalis, M., Hoffman, S. N., Han, J. J., Erlich, P. M., Gerhard, G. S., & Stewart, W. F. (2010). Risk factors for drug dependence among out‐patients on opioid therapy in a large US health‐care system. Addiction, 105(10), 1776-1782.
  3. Brown, R., Kraus, C., Fleming, M., & Reddy, S. (2004). Methadone: applied pharmacology and use as adjunctive treatment in chronic painPostgraduate medical journal, 80(949), 654–659.
  4. Faul M, Bohm M, Alexander C. Methadone Prescribing and Overdose and the Association with Medicaid Preferred Drug List Policies — United States, 2007–2014. MMWR Morb Mortal Wkly Rep 2017;66:320–323.
  5. Gros, D. F., Milanak, M. E., Brady, K. T., & Back, S. E. (2013). Frequency and severity of comorbid mood and anxiety disorders in prescription opioid dependence. The American Journal on Addictions, 22(3), 261-265.
  6. Kosten, T. R., & Baxter, L. E. (2019). Effective management of opioid withdrawal symptoms: A gateway to opioid dependence treatment. The American Journal on Addictions, 28(2), 55-62.
  7. Kreek, M. J., Borg, L., Ducat, E., & Ray, B. (2010). Pharmacotherapy in the treatment of addiction: methadone. Journal of addictive diseases, 29(2), 200-216.
  8. Lugo, R. A., Satterfield, K. L., & Kern, S. E. (2005). Pharmacokinetics of methadone. Journal of Pain & Palliative Care Pharmacotherapy, 19(4), 13-24.
  9. Martins, S. S., Keyes, K. M., Storr, C. L., Zhu, H., & Chilcoat, H. D. (2009). Pathways between nonmedical opioid use/dependence and psychiatric disorders: results from the National Epidemiologic Survey on Alcohol and Related Conditions. Drug and alcohol dependence, 103(1-2), 16-24.
  10. NIDA. (2020, May 27). Prescription Opioids DrugFacts, viewed November 20, 2020.
  11. Lipman, J. J. (2008). The Methadone Poisoning Epidemic, viewed November 16, 2020.
  12. Substance Abuse and Mental Health Services Administration. (2020, September 08). Methadone, viewed November 15, 2020.
  13. Terrett, G., McLennan, S. N., Henry, J. D., Biernacki, K., Mercuri, K., Curran, H. V., & Rendell, P. G. (2014). Prospective memory impairment in long-term opiate users. Psychopharmacology, 231(13), 2623-2632.
  14. U.S. Food and Drug Administration. (2006, October). DOLOPHINE® HYDROCHLORIDE CII (Methadone Hydrochloride Tablets, USP), viewed November 17, 2020.
  15. US National Library of Medicine. (2019, October 15). Methadone: MedlinePlus Drug Information, viewed November 17, 2020.
  16. U.S. National Library of Medicine. (2020, November 3). Opiate and opioid withdrawal: MedlinePlus Medical Encyclopedia, viewed November 17, 2020.

Where do calls go?

Calls to numbers on a specific treatment center listing will be routed to that treatment center. Additional calls will also be forwarded and returned by one of our treatment partners below.

Calls to any general helpline (non-facility specific 1-8XX numbers) for your visit will be answered by one of our treatment partners, a paid advertiser on

All calls are private and confidential.