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Psychedex
Facts label

Promethazine Facts

Depressant; Sedative; Phenothiazine; Histamine H1 receptor antagonist

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 5 mgLight12.5 – 25 mgCommon25 – 50 mgStrong50 – 100 mgHeavy100+ mg

Starts in 20 – 60 minLasts 4 – 8 hoursAfter-effects 6 – 12 hours

Body and dependence

Acute toxicity
Moderate
Chronic toxicity
Moderate
Physical dependence
Negligible
Psychological dependence
Low
Withdrawal
None recorded
Compulsive redosing
Negligible

Tolerance

Builds
Moderate
Fully resets after
Not recorded
Carries over to
diphenhydramine; chlorpheniramine; hydroxyzine; doxylamine; other first-generation H1 antihistamines; muscarinic antagonists

Effectslikely at a common dose

Perception
none likely · 8 possible, including Visual acuity suppression, Vestibular distortion, Spatial disorientation
Body
Sedation; Physical fatigue; Nausea suppression; Dry mouth; Bodily heaviness; Motor control impairment; +10 possible, including Dizziness, Abnormal heartbeat, Heart rate perception changes
Thinking
Focus suppression; Cognitive impairment; Thought deceleration; Cognitive fatigue; Decision impairment; Analysis suppression; Information processing suppression; +8 possible, including Memory suppression, Language suppression, Confusion
Feeling
none likely · 3 possible, including Empathy suppression
Self
none likely · 4 possible, including Communication suppression, Social disconnection
Time
none likely · 2 possible, including Temporal disorientation

Who shouldn't take it

Absolute
Comatose patients; Promethazine or phenothiazine hypersensitivity; Children under 2 years; Intra-arterial or subcutaneous injection
Relative
Concurrent QT-prolonging medications; Lower respiratory tract disease; Seizure disorders; Concurrent MAOI use; Hepatic impairment; Elderly patients; Narrow-angle glaucoma; Prostatic hypertrophy or bladder obstruction; Bone marrow suppression history

Combinations60 recorded

Dangerous (30)
Amphetamines; Anticholinergics; Antihistamines; Atypical antipsychotics; Benzodiazepines, Barbiturates; Buprenorphine, Kratom; DXM; GHB, Baclofen; GHB, GBL; Lithium; MDMA, MDA; Naltrexone; Opioids; Alpha-2 adrenergic receptor antagonist; Benzodiazepines; Clonidine, Guanfacine; Ephedrine, Pseudoephedrine; Ibogaine; Local anesthetics; MAOIs; MDMA, Amphetamines; NDRIs (Wellbutrin); NRIs; NSAIDs; and 6 more, see full page
Caution (25)
See full page: psychedex.org/substances/promethazine
Not graded (5)
Not listed never means safe.

Seek help immediately if

No emergency profile is recorded for this substance. Not recorded never means no risk.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

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