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Psychedex
Facts label

Diphenidine Facts

Dissociative; Diarylethylamine; NMDA receptor antagonist

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 15 mgLight40 – 75 mgCommon75 – 120 mgStrong120 – 175 mgHeavy175+ mg

Starts in 15 – 30 minLasts 2 – 5 hoursAfter-effects 4 – 24 hours

Also recorded: Rectal · Smoked. See full page: psychedex.org/substances/diphenidine

Body and dependence

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

Tolerance

Builds
Moderate
Fully resets after
10 days
Carries over to
ketamine; phencyclidine; methoxetamine; methoxphenidine; dextromethorphan

Effectslikely at a common dose

Perception
Spatial disorientation; +21 possible, including Double vision, Visual acuity suppression, Vestibular distortion
Body
Motor control impairment; +23 possible, including Dizziness, Nystagmus (eye wobbles), Nausea
Thinking
Cognitive impairment; +21 possible, including Memory suppression, Analysis suppression, Confusion
Feeling
none likely · 5 possible, including Anxiety, Emotional lability
Self
Derealization; +8 possible, including Depersonalization, Communication suppression, Social disconnection
Time
Time alteration; +2 possible, including Temporal disorientation

Who shouldn't take it

Absolute
Psychotic disorders; Pregnancy and breastfeeding
Relative
Hypertension; Cardiac arrhythmia; Bipolar disorder; Hepatic impairment; Renal impairment

Combinations61 recorded

Lethal (2)
GHB, GBL; Ibogaine
Dangerous (36)
Amphetamines; Benzodiazepines; Buprenorphine, Kratom; Ephedrine, Pseudoephedrine; MDMA, Amphetamines; Naltrexone; NDRIs (Wellbutrin); NRIs; NSAIDs; Opioids; THC; Anticholinergics; Antihistamines; Atypical antipsychotics; Benzodiazepines, Barbiturates; Buspirone; Caffeine; Clonidine, Guanfacine; Dopamine agonists; DXM; Gabapentin, Pregabalin; GHB, Baclofen; Ketamine, DXM, PCP; Lithium; and 12 more, see full page
Caution (20)
See full page: psychedex.org/substances/diphenidine
Not graded (3)
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

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