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Psychedex
Facts label

Methadone Facts

Opioid; Depressant; Diphenylpropylamine; Mu-opioid receptor agonist

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 1 mgLight2.5 – 10 mgCommon10 – 25 mgStrong25 – 50 mgHeavy50+ mg

Starts in 20 – 90 minLasts 10 – 19 hoursAfter-effects 1 – 24 hours

Body and dependence

Acute toxicity
Critical
Chronic toxicity
High
Physical dependence
High
Psychological dependence
High
Withdrawal
Severe · medical supervision
Compulsive redosing
Moderate

Tolerance

Builds
Moderate
Fully resets after
10 days
Carries over to
morphine; heroin; oxycodone; hydrocodone; fentanyl; codeine; buprenorphine; tramadol; hydromorphone

Effectslikely at a common dose

Perception
none likely · 1 possible
Body
Sedation; Pain suppression; Constipation; Pupil constriction; +20 possible, including Respiratory depression, Nausea, Excessive sweating
Thinking
none likely · 13 possible, including Compulsive redosing urge, Analysis suppression, Cognitive impairment
Feeling
none likely · 6 possible, including Anhedonia, Depression
Self
none likely · 6 possible, including Communication suppression, Craving, Social disconnection
Time
none likely · 3 possible, including Temporal disorientation

Who shouldn't take it

Absolute
Long QT syndrome; Severe respiratory insufficiency; Concurrent MAOI use
Relative
QT-prolonging medications; Hepatic impairment; CYP2B6 poor metabolizer phenotype; Pregnancy; Concurrent benzodiazepine use

Combinations62 recorded

Lethal (7)
Benzodiazepines, Barbiturates; GHB, Baclofen; GHB, GBL; Ketamine; Local anesthetics; MAOIs; Tramadol
Dangerous (39)
Alpha-2 adrenergic receptor antagonist; Amphetamines; Anticholinergics; Antihistamines; Benzodiazepines; Buprenorphine, Kratom; Cannabis, THC; Clonidine, Guanfacine; Gabapentin, Pregabalin; MDMA, Amphetamines; MDMA, MDA; Naloxone, Naltrexone; Naltrexone; NRIs; NSAIDs; Stimulants; THC; 5-HTP, Tryptophan; Antipsychotics; Atypical antipsychotics; Buspirone; Caffeine; CBD; Dopamine agonists; and 15 more, see full page
Caution (12)
See full page: psychedex.org/substances/methadone
Not graded (4)
Not listed never means safe.

Seek help immediately if

  • Unresponsive / can't be woken, even to a firm sternal rub
  • Slow, shallow, or stopped breathing
  • Pinpoint pupils
  • Blue/grey lips, fingertips, or skin (cyanosis)
  • Limp body; pale, clammy skin
  • Choking or gurgling sounds ("death rattle")
  • Slow, erratic, or absent pulse

What to do

  1. Try to wake them — shout their name, firm sternal rub
  2. Call emergency services immediately
  3. Administer naloxone if available
  4. Give rescue breaths (or CPR if there is no pulse)
  5. Place them in the recovery position
  6. Stay with them; re-dose naloxone every 2–3 minutes if there is no response
Reversal agent
Naloxone (Narcan) — opioid antagonist. May require repeated doses; its effect can wear off before the opioid does.

With prompt naloxone and rescue breathing, reversal is usually rapid. Because naloxone can wear off before the opioid — especially with long-acting opioids (methadone) or high-potency ones (fentanyl) — a period of monitoring is needed even after the person revives.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

psychedex.org/substances/methadone · Version r1 · Not medical adviceValues as of
On the printout