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Methoxphenidine Facts

Dissociative; Diarylethylamine; NMDA receptor antagonist

Description

MXP (methoxphenidine) is a synthetic dissociative of the diarylethylamine class. MXP blocks glutamate signaling in the brain, disrupting how information is integrated — producing the cognitive and perceptual detachment characteristic of dissociatives.[1]

Subjective effects include cognitive disconnection, derealization, spatial disorientation, visual suppression, and alternating waves of stimulant-like energy and heavy sedation.[2] The experience is defined by its unpredictable, biphasic character — energy and heaviness cycling in ways that shift decisively toward immobility at higher doses.

Physical dependence can develop after short periods of heavy use,[3] and 31 UK deaths have been linked to MXP.[4] Street samples frequently contain synthesis impurities that dramatically amplify toxicity beyond what the compound itself produces,[5] and most deaths involved other substances.

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 30 mgLight50 – 75 mgCommon75 – 120 mgStrong120 – 150 mgHeavy150+ mg

Starts in 30 – 60 minLasts 6 – 8 hoursAfter-effects 1 – 3 hours

Body and dependence

Acute toxicity
High
Chronic toxicity
Moderate
Physical dependence
Moderate
Psychological dependence
Moderate
Withdrawal
Mild
Compulsive redosing
Moderate

Tolerance

Builds
Moderate
Fully resets after
10 days
Carries over to
dissociatives

Effectslikely at a common dose

Perception
none likely · 16 possible, including Spatial disorientation, Vestibular distortion, Double vision
Body
Motor control impairment; +19 possible, including Dizziness, Nystagmus (eye wobbles), Heart rate perception changes
Thinking
Cognitive impairment; +21 possible, including Memory suppression, Confusion, Decision impairment
Feeling
none likely · 6 possible, including Anxiety, Emotional lability, Empathy suppression
Self
Derealization; +6 possible, including Depersonalization, Communication suppression, Social disconnection
Time
none likely · 2 possible, including Temporal disorientation

Who shouldn't take it

Absolute
Hypertension; Coronary artery disease; Epilepsy; Psychotic disorders; Pregnancy
Relative
Hepatic impairment

Combinations61 recorded

Lethal (1)
GHB, GBL
Dangerous (30)
Antihistamines; Benzodiazepines; Benzodiazepines, Barbiturates; Buprenorphine, Kratom; Naltrexone; NSAIDs; Opioids; THC; Anticholinergics; Antipsychotics; Buspirone; Clonidine, Guanfacine; Dopamine agonists; Gabapentin, Pregabalin; GHB, Baclofen; Ibogaine; Ketamine, DXM, PCP; Lithium; Local anesthetics; MAOIs; MDMA, Amphetamines; MDMA, MDA; NDRIs (Wellbutrin); NRIs; and 6 more, see full page
Caution (24)
See full page: psychedex.org/substances/methoxphenidine
Not graded (6)
Not listed never means safe.

Seek help immediately if

  • Severe disorientation; unable to move or speak (deep dissociation / "k-hole")
  • Complete loss of coordination — cannot stand or walk safely
  • Vomiting while incapacitated (choking / aspiration risk)
  • Very high blood pressure; fast heart rate
  • Slow or shallow breathing at high doses (especially mixed with depressants)
  • Unconsciousness; rarely, seizures

What to do

  1. Move them somewhere safe, away from stairs, water, roads, and sharp edges — they cannot protect themselves
  2. Place in the recovery position if vomiting or unconscious (aspiration is a key risk)
  3. Stay with them and reassure calmly; keep the environment quiet
  4. If breathing is slow/shallow or they are unresponsive, call emergency services
  5. Do not let them wander; do not leave them alone
  6. Be ready to give rescue breaths / CPR

Effects wear off with time in a safe, monitored setting. The main dangers are physical injury and aspiration while incapacitated, and respiratory depression when combined with other depressants — not the dissociation itself.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1 · Not medical advice

References

  1. [1]
    ^Wallach J, Kang H, Colestock T, Morris H, Bortolotto ZA, Collingridge GL, Lodge D, Halberstadt AL, Brandt SD, Adejare A (2016) Pharmacological Investigations of the Dissociative 'Legal Highs' Diphenidine, Methoxphenidine and Analogues — PLoS ONE doi:10.1371/journal.pone.0157021
  2. [2]
    ^Van Hout MC, Hearne E (2015) "Word of mouse": indigenous harm reduction and online consumerism of the synthetic compound methoxphenidine — Journal of Psychoactive Drugs doi:10.1080/02791072.2014.974002
  3. [3]
    ^Advisory Council on the Misuse of Drugs (ACMD) (2023) ACMD Review of the Evidence on the Use and Harms of Diphenidine (including methoxphenidine) Link
  4. [4]
    ^Corkery JM, Copeland C, Schifano F (2025) Deaths related to the use of diarylethylamines, with a focus on the United Kingdom: A systematic review and case series report — Journal of Psychopharmacology doi:10.1177/02698811251349203
  5. [5]
    ^Jurásek B, Rimpelová S, Babor M, Čejka J, Bartůněk V (2022) Intriguing Cytotoxicity of the Street Dissociative Anesthetic Methoxphenidine: Unexpected Impurities Spotted — International Journal of Molecular Sciences doi:10.3390/ijms23042083
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