Both heroin and methadone are opioids that act on the same receptors in the brain, but they work differently and last longer in the body.
When someone who is dependent on either of these substances stops or reduces their use, opioid withdrawal occurs.
Understanding the clinical differences between heroin withdrawal and methadone withdrawal is important for healthcare professionals, patients and families going through treatment and recovery.
Opioid Withdrawal
Opioid withdrawal is a physiological process that happens when someone who has become dependent on opioids stops or reduces their drug use. The body, having adapted to the regular presence of opioids, responds to their absence with a predictable set of opioid withdrawal symptoms.
These withdrawal symptoms are mainly due to:
Autonomic nervous system overactivity
Central nervous system dysregulation
Gastrointestinal disturbance
It’s important to remember that individual experiences vary greatly.
Duration and intensity of substance use, overall health, mental health status and social circumstances all impact how withdrawal presents and progresses.
NHS and NICE guidance recognises opioid withdrawal as a clinical syndrome that requires assessment and where necessary medical management.
In UK clinical practice the focus is on safety, harm reduction and connecting individuals with treatment options.
Key Differences at a Glance
The main difference between heroin withdrawal and methadone withdrawal is onset, duration and symptom intensity.
Onset
Heroin withdrawal starts relatively quickly after last use, methadone withdrawal takes longer due to the drug’s longer half life.
Duration
Heroin withdrawal is shorter and more acute. Methadone withdrawal is longer and more gradual.
Intensity pattern
Heroin withdrawal is described as more abrupt and intense at peak, methadone withdrawal is less severe at any one time but more overall.
Key points
Heroin is a short acting illegal opioid with rapid withdrawal onset
Methadone is a long acting prescribed opioid used in opioid substitution therapy
General differences in duration and symptom pattern but individual variation is big
Withdrawal from heroin or methadone is not usually life threatening in otherwise healthy adults. However risk is increased when:
Alcohol or benzodiazepines are also being used
The person is pregnant
There are significant chronic medical conditions
This is informational only and not a treatment plan. Anyone experiencing or concerned about opioid withdrawal should consult healthcare professionals for individual advice.
NHS and NICE Context on Opioid Dependence
In the UK the NHS and NICE provide clinical guidance on managing opioid use disorder and opioid dependence. These guidelines promote evidence based treatment and harm reduction.
Key points from this context are:
Methadone and buprenorphine are first line medicines for opioid substitution therapy
The goal of substitution treatment is to stabilise patients, reduce illicit drug use and support recovery
There is a clear distinction between illicit heroin use and the prescribed, supervised use of methadone as part of drug treatment
Harm reduction including overdose prevention through naloxone provision is a key principle
NHS drug and alcohol services, GPs and hospital teams all play a role in supporting individuals with opioid dependence. The focus is on accessible non-judgemental care that addresses physical health and broader support needs.
Heroin and Methadone
What Is Heroin?
Heroin is an illegal, short acting opioid derived from morphine. It is usually injected, smoked or snorted.
Key points:
Rapid onset of effects (seconds to minutes depending on route)
Short duration of action, effects wear off in a few hours
Variable purity and supply, unpredictable risks
Often used in a pattern of frequent dosing throughout the day
Because heroin clears the body quickly individuals who are dependent will experience withdrawal within hours of last use.
What Is Methadone?
Methadone is a long acting synthetic opioid licensed in the UK for the treatment of opioid dependence. It is usually dispensed as an oral liquid under medical supervision.
Key points:
Slow onset and prolonged duration of action
Half life typically over 24 hours (range 15–60 hours)
Taken once daily in most treatment regimens
Prescribed as part of structured drug treatment programmes
Methadone is designed to provide stable opioid receptor activity without the peaks and troughs of heroin use. This stability supports harm reduction and engagement with broader recovery services.
Pharmacology and Opioid Receptors
Both heroin and methadone work by binding to mu-opioid receptors in the brain and body. With repeated use the brain adapts to the presence of opioids and tolerance and physical dependence develops.
The key pharmacological difference is half life:
Heroin has a very short half life (30 minutes)
Methadone has a much longer half life (15–60 hours)
This difference directly impacts withdrawal. When heroin is stopped receptor occupancy drops rapidly and an abrupt noradrenergic rebound occurs. When methadone is stopped or reduced receptor activity declines more gradually and withdrawal starts slower but is more prolonged.
Onset and Time Course of Withdrawal
Heroin Withdrawal Timeline
Heroin withdrawal follows a relatively predictable course although individual variation exists.
Onset: Symptoms usually start within 6–12 hours of last use
Peak: Symptoms peak around 1–3 days
Resolution: Most physical symptoms ease within 5–7 days
Protracted symptoms: Some individuals experience persistent sleep disturbance, low mood and fatigue for weeks beyond the acute phase
The early symptoms can be intense and patients often describe the experience as overwhelming. However the short duration means acute physical discomfort usually passes within about a week.
Methadone Withdrawal Timeline
Methadone withdrawal has a different time course due to the drug’s long half life.
Onset: Symptoms may not start until 1–3 days after last dose
Development: Symptoms often build gradually rather than suddenly
Duration: Physical symptoms can last 2–4 weeks or longer in some cases
Protracted symptoms: Insomnia, fatigue and mood disturbance may extend well beyond the acute phase
The slower onset can sometimes lead individuals to underestimate the severity of impending withdrawal. The prolonged nature of methadone withdrawal can be particularly challenging as discomfort may persist at a lower but more sustained level.
Factors Influencing Withdrawal Timelines
No two individuals experience withdrawal the same way. Key factors that influence the time course and severity are:
- Dose and duration of use: Higher doses and longer use generally lead to more severe withdrawal
Individual metabolism: Genetic and physiological differences affect how quickly opioids are cleared from the body
Physical and mental health: Pre-existing conditions, particularly liver function, can affect drug metabolism
Concurrent substance use: Use of other drugs, including alcohol, benzodiazepines or other opioids such as codeine, fentanyl or oxycodone can complicate the clinical picture
Clinicians should be aware that patients taking oxycontin or other prescribed opioids for pain relief may also experience withdrawal if these medicines are stopped suddenly.
Withdrawal Symptoms: Similarities and Differences
Shared Physical Symptoms
Both heroin and methadone withdrawal have common physical symptoms reflecting autonomic and gastrointestinal overactivity:
Muscle aches and bone pain
Nausea, vomiting and diarrhoea
Sweating and chills (often alternating)
Restlessness and unable to stay still
Insomnia and disturbed sleep
Runny nose and increased tearing
Dilated pupils
Goosebumps (piloerection)
Yawning
These symptoms can be mild or severe and are often compared to a very intense flu-like illness.
Shared Psychological Symptoms
Psychological symptoms are also common to both:
Anxiety and agitation
Irritability and mood swings
Low mood and depression
Strong cravings for opioids
Difficulty concentrating and cognitive fatigue
These psychological symptoms can persist beyond the resolution of physical symptoms and may require ongoing support.
Clinical Assessment and Monitoring
Structured clinical assessment is important when assessing someone in opioid withdrawal. This applies whether the person is withdrawing from heroin, methadone or other opioids.
Assessment will include:
History: What substances are being used, when last used, how long and how often used, and previous withdrawal experiences
Physical examination: Pulse, blood pressure, temperature, pupil size, hydration status and signs of infection
Urine toxicology: Confirms recent opioid use and screens for other drugs
Blood tests: May include liver function tests and full blood count if indicated, particularly in patients with chronic health conditions
The clinical opiate withdrawal scale (COWS) is a validated tool used in many clinical settings to rate withdrawal severity. It scores objective signs such as heart rate, sweating, restlessness, pupil size, bone or joint pain, runny nose, gastrointestinal upset, tremor, yawning, anxiety and piloerection. Scores guide clinical decision making:
Mild withdrawal: scores below 5
Moderate to severe: scores above this threshold
Observation time differs between substances:
For heroin, withdrawal signs may appear within hours of last use
For methadone, observation may need to be over a longer period before withdrawal becomes apparent
Screen for concurrent risks:
Alcohol use (risk of concurrent alcohol withdrawal which can be dangerous)
Benzodiazepine use (withdrawal from these substances carries seizure and delirium risk)
Mental health concerns including suicidal thoughts or severe anxiety
Honest discussion with patients about all substance use is crucial for safe care.
Heroin Withdrawal in Practice
Heroin withdrawal is common in emergency departments, acute hospital wards and community drug treatment services.
Presentations:
Patients admitted for other conditions (e.g. infections, injuries) who develop withdrawal in hospital
Individuals presenting specifically because of withdrawal symptoms
People who have run out of supply or been unable to access heroin
Rapid onset is characteristic, symptoms often appear within hours of loss of access to heroin. This can catch patients and clinicians off guard if the underlying dependence was not identified.
Common co-morbidities:
Infections related to injecting (hepatitis B, hepatitis C, HIV, skin abscesses)
Poor nutrition
Mental health conditions including depression and anxiety* Social instability affecting access to care
NICE-guided management recommends starting opioid substitution therapy (usually methadone or buprenorphine) as soon as possible to stabilise the patient and reduce the risk of going back to heroin.
Unmanaged withdrawal risks:
Severe discomfort may lead to discharge against medical advice
Relapse to heroin use, often at a dose the body can no longer tolerate, increasing overdose risk
Dehydration from vomiting and diarrhoea
Clinicians should be aware that treating withdrawal as a short-term issue without linking to ongoing care increases the risk of poor outcomes.
Methadone Withdrawal in Substitution Therapy
Methadone is prescribed as a stabilising treatment in opioid substitution therapy. It reduces the harms of heroin use while supporting recovery.
Common reasons for methadone withdrawal:
Planned dose reduction: Some patients want to reduce their methadone dose over time, ideally under medical supervision
Missed doses or treatment interruption: Prescriptions may be missed due to logistical issues, illness or changes in social circumstances
Transfer of care: Gaps can occur when patients move between services or are admitted to hospital
Symptom pattern:
Symptoms often don’t start until 1-3 days after the last dose
Once started, symptoms may build up gradually
Prolonged insomnia, fatigue and low mood are common
Physical symptoms can last for weeks
Clinical considerations:
After missed home doses, cautious reassessment is needed before resuming the usual dose as tolerance may have decreased
Any planned reduction should be reviewed and discussed with the prescribing team
The next review should consider both physical symptoms and mental wellbeing
Methadone withdrawal while less intense than heroin withdrawal can be challenging due to its duration. Patients may find the prolonged discomfort hard to tolerate and this can affect treatment adherence.
Risks and Complications
Opioid withdrawal is not life-threatening in healthy adults but complications can occur:
Dehydration and electrolyte imbalance: Severe vomiting and diarrhoea can lead to significant fluid loss which may require medical attention
Exacerbation of underlying conditions: Patients with heart disease, respiratory conditions or liver disease may experience worsening symptoms during withdrawal
Relapse and overdose: The biggest risk after unmanaged withdrawal is going back to opioid use. Tolerance drops rapidly during abstinence so previously tolerated doses can cause fatal overdose
Mental health deterioration: Anxiety, depression and suicidal thoughts may emerge or worsen during withdrawal
Harm reduction measures are crucial:
Naloxone for overdose reversal
Connection to drug treatment services
Ongoing support for mental health
Access to support groups and community resources
Patients should be told the risk of overdose is highest in the period immediately after leaving hospital, prison or completing detox.
When to Get Medical Help
Anyone experiencing opioid withdrawal should consider getting medical help especially if symptoms are severe or if there are concerns about safety.
UK sources of help:
GP and primary care: Can assess symptoms, prescribe supportive medication and refer to specialist services
NHS drug and alcohol services: Provide structured treatment for heroin withdrawal, including opioid substitution therapy
Hospital teams: For severe withdrawal, medical complications or other health conditions
Community pharmacies: Many offer supervised consumption of methadone and can provide advice and support
Emergency warning signs that need urgent medical attention:
Severe dehydration (can’t keep fluids down, dizziness, reduced urine output)
Chest pain or severe shortness of breath
Confusion or altered consciousness
Seizures
High fever
Suicidal thoughts or severe mental health crisis
If unsure contact NHS 111 or go to your local A&E.
Recap
Heroin withdrawal and methadone withdrawal are both opioid withdrawal and share many symptoms but are different in onset, duration and pattern.
Key differences:
Heroin withdrawal starts quickly (hours), peaks intensely and resolves in about a week
Methadone withdrawal begins more gradually (1-3 days after last dose), builds up slowly and can last several weeks
Important points:
Individual experiences vary depending on dose, duration of use, metabolism and overall health
Both are uncomfortable but not life-threatening in healthy adults
Risk increases when alcohol, benzodiazepines or other drugs are involved
Unmanaged withdrawal is associated with high relapse and overdose rates
This article is aligned with NHS and NICE clinical guidance and is for information only. It does not replace individual medical advice.
If you or someone you know is dependent on heroin, methadone or other opioids get help. Contact your GP, local NHS drug and alcohol service or call NHS 111 for guidance on what to do next.
