Methadone Side Effects & Warnings | Common, Severe, & Long-Term

Methadone side effects give off a range of warnings. Find out more about common, severe, and long term side effects of Methadone abuse.

Methadone (brand name Dolophine or Methadose) is a prescription opioid medication used for pain relief. It belongs to a class of medications known as opiate (narcotic) analgesics.

Methadone is a helpful medication used for those suffering from severe pain and opioid addiction. It works by binding to the pain receptors in the brain and depressing the central nervous system (CNS).

This medication is part of a schedule II class of drugs determined by the Controlled Substances Act, which means methadone has a high potential for abuse. There are also a number of side effects caused by methadone use.

Methadone Side Effects

According to the United States Food and Drug Administration (FDA), the side effects of methadone range in severity from common to severe.


The common side effects of methadone use may include:

  • itchy skin
  • dry mouth
  • nausea
  • drowsiness
  • ​slow breathing
  • ​restlessness
  • sleepiness
  • sexual dysfunction
  • constipation
  • vomiting
  • loss of appetite
  • sweating


The less common and more severe side effects of methadone use can include:

  • blood pressure fluctuations
  • respiratory depression
  • ​hallucinations
  • chest pain
  • ​confusion
  • breathing problems such as shallow breathing
  • skin rash
  • lightheadedness
  • fluctuations in heart rate or irregular heartbeat


The long-term side effects of methadone use may include:

Methadone Warnings

Because methadone can cause adverse reactions, drug interactions, and even allergic reactions, it’s important to inform your doctor if you:

  • are breastfeeding, as methadone can be passed through breast milk
  • have liver, gallbladder, or kidney disease
  • have ever had a head injury
  • take drugs used to treat seizures such as carbamazepine
  • or anyone in your family has ever had a heart problem such as QT prolongation
  • take MAO inhibitors (MAOIs) or selective serotonin-reuptake inhibitors (SSRIs)
  • take rifamycins (such as rifampin)

Methadone Abuse

The dispersible methadone oral tablets can be crushed into powder. Once in powder form, methadone can be snorted or mixed with a liquid for intravenous injection.

Depending on the route of administration, methadone may enter your bloodstream at a faster pace. Those who snort methadone may experience feelings of euphoria more quickly, but can cause damage to their nasal cavity and sinuses.

Others may turn to intravenously injecting methadone into their veins. This type of drug abuse is particularly dangerous, as it can cause abscesses on your skin, collapsed veins, and make you susceptible to diseases such as HIV or hepatitis if you engage in sharing needles with others living with drug addiction.

Tolerance & Dependence

Long-term opioid use can lead to a risk of tolerance. When this happens, a person may begin taking a higher dose of methadone or experimenting with other drugs to achieve the same “high” they once experienced.

Those suffering with chronic pain may also develop an opioid dependence over time, which means withdrawal symptoms may occur when they stop use.

Withdrawal Symptoms

Those taking methadone who abruptly stop their medication may experience opioid withdrawal symptoms that may include:

  • anxiety
  • stomach cramps
  • chills
  • runny nose
  • joint pain
  • vomiting
  • sleeping difficulty

Combining Medications

Combining certain medications with methadone can lead to a number of health concerns. For instance, CNS depressants such as benzodiazepines, muscle relaxants, sedatives, and alcohol should not be combined with methadone as you may experience trouble breathing.

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), the use of prescription drugs, as well as over-the-counter medications such as antihistamines that can cause drowsiness, may elevate your sedation.

When CNS depressants are combined with a powerful pain medication such as methadone, it can increase your risk of overdose and cause life-threatening symptoms.


If you suspect that a person is suffering from an overdose, seek medical attention right away.

The use of methadone in large quantities can lead to various overdose symptoms such as:

  • pinpoint pupils
  • clammy skin
  • blue skin
  • limp muscles
  • drowsiness

At the emergency room, a healthcare professional may use the medication naloxone to help reverse the effects of an overdose. Even still, you may require additional treatment.

Treatment For Opioid Addiction

For a successful outcome treating substance abuse, you’ll likely want to undergo a detox program. Throughout the detoxification process, your body will get rid of the toxins caused by repeated drug use.

In addition to this, your healthcare provider may prescribe you supplements or other medications like buprenorphine to assist in treatment.

For information on our outpatient treatment programs, including medication-assisted treatment, please connect with us today.

Written by
Northeast Addition Editorial Team

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This page does not provide medical advice.

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