What Are The Effects Of Methadone?

Taking methadone could delay and/or eliminate heroin withdrawal symptoms [1].

Methadone is a synthetic opioid like heroin, tramadol and fentanyl. Primarily, it causes:

  • Pain relief
  • Sleepiness or drowsiness
  • Sedation

When an opioid dependent individual takes methadone, it does not cause feelings of euphoria. Rather, withdrawal symptoms and opioid cravings are relieved.

Withdrawal symptoms curbed or eliminated by taking methadone include insomnia, carvings for heroin, fever and moodiness.

Taking methadone can also lead to some side effects. These are [2]:

  • Some difficulty breathing or shallow breathing
  • Lightheadedness or feeling faint
  • Allergic skin reactions
  • Chest pains
  • Fast heartbeat
  • Some may feel confused or disoriented

Side effects should be reported immediately in case they are signs of serious trouble.

Total abstinence from heroin is challenging. As this is the case, some individuals rely on methadone to stabilise before undergoing a rehab programme like that at Abbeycare Scotland.

How Often Can You Take Methadone?

Methadone is usually taken only once a day.

The typical dosage for methadone is 20 to 30 mg.

This dose is often enough to make withdrawal symptoms tolerable. An additional 5 to 10 milligrams is given if the first dose is not working.

A total daily dose usually does not exceed 40 mg [3].

Methadone works by stopping cravings for heroin and other opioids such as oxycodone and fentanyl.

In the UK, methadone is used in Methadone Maintenance Therapy (MMT) by the NHS.

Some addiction clinics also use methadone as part of its in-patient programme.

Methadone helps with opioid cravings by reducing the withdrawal symptoms of heroin, morphine and other prescription drugs.

Examples of these withdrawal symptoms are:

  • Irritability and moodiness
  • Anxious feelings
  • Feeling tired or fatigued
  • Depression
  • An increased heart rate
  • Muscle pains or cramps
  • Stomach pains
  • Nausea
  • Fever and chills
  • Vomiting
  • Diarrhea
  • Tremors
  • Muscle spasms

Methadone is dispensed by the NHS and other private facilities because there is a risk of diverting the drug for illegal use.

A single dose usually lasts for 24 to 36 hours. NHS clinic services are free, and will often provide other helpful services for people who seek to limit or stop drug use.

How Long Does It Take For Liquid Methadone To Absorb?

After swallowing liquid methadone, it can usually be absorbed by the body in as little as one hour.

But due to differing metabolism and other factors, some individuals could respond differently to the drug, taking up to 7 hours for full absorption [4].

Because methadone is not immediately absorbed by the body, some individuals may not feel complete relief from withdrawal symptoms a short time after they take it.

If methadone is being taken as part of a drug rehab programme, there is a need to be in touch with addiction experts during the process.

Drug detox using methadone has caused deaths because of complications with existing heart problems [5].

The WHO lists methadone as one of its essential medications because of its proven efficacy. Specifically, methadone is used two ways:

  1. Methadone Management Therapy (MMT)
  2. Methadone-assisted detoxification

For MMT, authorities view opioid addiction as a lifetime disease.

Using this way of thinking, methadone is used as a maintenance drug very much like how individuals with diabetes use insulin—as a drug that they have to take to keep functioning properly [6].

In the UK, MMT is used by the NHS. It is believed that long-term opioid abuse causes a form of damage in the central nervous system that makes individuals who want to stop using it feel sick.

By using methadone, individuals who quit opiates such as heroin and fentanyl tend to be able to cope better.

The second way of using methadone typically treating it as part of medically assisted detox, where methadone is the only the first part of a structured rehab programme.

After detox, individuals in a rehab programme usually attend therapy sessions, then rehab aftercare.

Some individuals misunderstand the use of methadone in MMT as “substituting one drug for another”.

There can be shame and stigma if an individual seeks methadone treatment because of this way of thinking.

Current research [6] proves that methadone could be effective in helping individuals stop using heroin and other illegal drugs.

In fact, MMT may prevent the spread of HIV through lessening the need for needle sharing.

MMT tend to curb criminal behaviour associated with drug use. The WHO has listed methadone as one of its essential medicines [6].

Is Methadone Free To Addicts?

In the UK, the NHS provide a daily dose of methadone to individuals who utilise either of the two approaches utilised to stop heroin misuse [7].

These approaches are Methadone Maintenance Therapy (MMT) and detox with the assistance of methadone.

Because heroin dependence is a condition where individuals tend to relapse, abstinence could be hard to achieve for many.

The NHS decided to prescribe methadone and buprenorphine as a form of substitution treatment.

It is not about substituting one drug for another because although methadone can be addictive, substitution treatment can help stabilise individuals to be able to undergo rehab and talk therapies [8].

Substitution treatment also aims to offer a legal and safe heroin or opiate substitute so that addicted individuals can reduce risky behaviours.

How Long Does It Take To Stabilise On Methadone?

It takes about two weeks to stabilise an individual using methadone in Methadone Management Therapy [9].

There are no set rules on the duration of Methadone Management Therapy (MMT). But the longer an individual stays on the programme, the better the chances are for behavioural change.

In the UK, the NHS strongly believes that MMT is the solution to resolving the problem of heroin/morphine/fentanyl abuse. Aside from MMT, the other approach is to use methadone as part of drug detox [7].

Although long-term abstinence from illegal opioids is the end goal of methadone treatment approaches, some individuals are not able to achieve this goal.

This is because methadone is addictive, just like other opioids. Some individuals on MMT have gotten addicted to methadone and require a detox from methadone in order continue living a sober life [2].

The NHS methadone approaches work on the premise that there are support services after methadone administration—it appears that methadone alone cannot solve the problem.

The quality of the NHS treatment programme, including the capacities of the staff, the services of the local drug services, and the treatment methods used are important in determining the success of methadone treatment [1].

However, because waiting for approval by NHS for methadone detox service takes time, some individuals chose private rehab instead. In addition, methadone addiction could be a tricky issue to talk about with a professional who works for the NHS.

Detoxing from methadone addiction is a serious concern, and in a private in-patient rehab setting, there could be a greater chance of recovery than in public programmes because private rehab centre services are more comprehensive and timely [10].

Most of all, the admission process in most private rehabs take only a matter of days.

Likewise, unlike NHS services, private clinics offer:

  • A lower staff-to-patient ratio
  • Better amenities
  • Personalised treatment
  • Continuation in care
  • Rehab aftercare

There is another drawback to the methadone treatment offered to the public: some individuals who use illegal opioids do not want methadone treatment.

Some may have tried methadone treatment, disliked it, or found it ineffective.

Some individuals are unable to manage on the prescribed dose and some continue to use illegal opioids to ‘top-up’ their prescription.

And lastly, some individuals do not like to give up injecting drugs. Apparently, the ritual of injecting is an experience that sometimes becomes a focus for addiction [1].



  1. Stimson, G. V. and Metrebian, N. (2003). Prescribing heroin: What is the evidence? Joseph Rowntree Foundation.  Available at:
  2. Substance Abuse and Mental Health Services Administration. (2015). Methadone. Available at:
  3. National Alliance on Mental Illness. (2016). Methadone® Available at:
  4. US Food and Drug Administration. (2015). Methadone Hydrochloride (marketed as Dolophine) Information. Available at:
  5. Harvard Medical School. (2019). Treating opiate addiction, part I: Detoxification and maintenance. Available at:
  6. Australian Government Department of Health. (2013). Four principles of methadone maintenance therapy. Available at:
  7. National Health Service. (2017). Heroin addiction: get help. Available at:
  8. National Institute for Health and Care Excellence. (2007). Methadone and buprenorphine for the management of opioid dependence. Technology appraisal guidance. Available at:
  9. Australian Government Department of Health. (2015). Induction to methadone treatment. Available at:
  10. National Institute on Drug Abuse. (2013). Principles of Drug Addiction Treatment: A Research-Based Guide (Third Edition). Available at:

About the author

Melany Heger

Registered Psychologist and Freelance Writer, Jinjin Melany passionately writes about mental health issues, addiction, eating disorders and parenting since 2015. Read more about Melany on LinkedIn. Content reviewed by Laura Morris (Clinical Lead).