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Psychedex
Facts label

2C-T-21 Facts

Psychedelic; Substituted phenethylamine; Serotonin 2A receptor agonist

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 5 mgLight5 – 10 mgCommon8 – 12 mgStrong12 – 15 mgHeavy15+ mg

Starts in 90 – 120 minLasts 7 – 12 hoursAfter-effects 2 – 4 hours

Body and dependence

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

Tolerance

Builds
Rapid
Fully resets after
7 days
Carries over to
LSD; psilocybin; mescaline; DMT; 2C-B; 2C-T-2; 2C-T-7

Effectslikely at a common dose

Perception
Music enhancement; Visual drifting; Brightness alteration; Geometry; Visual breathing; Color enhancement; Color alteration; +22 possible, including Visual haze / noise, Spatial disorientation, Visual acuity suppression
Body
Body high; Body scan awareness; Spontaneous body sensations; Pupil dilation; +32 possible, including Muscle tension, Nausea, Heart rate perception changes
Thinking
Pattern recognition enhancement; Aesthetic enhancement; Introspection enhancement; Openness enhancement; Thought connectivity; Novelty enhancement; Conceptual thinking; +25 possible, including Decision impairment, Suggestibility enhancement, Cognitive impairment
Feeling
Emotional enhancement; +6 possible, including Emotional lability, Anxiety
Self
none likely · 9 possible, including Derealization, Depersonalization
Time
Time alteration; +4 possible, including Temporal disorientation
Transpersonal
none likely · 1 possible
Awareness
none likely · 4 possible

Who shouldn't take it

Absolute
Psychotic disorders; Pregnancy and lactation; MAOI therapy
Relative
Cardiovascular disease; Seizure disorders; Hepatic impairment; Serotonergic medications

Combinations60 recorded

Lethal (6)
Amphetamines; MDMA, Amphetamines; MDMA, MDA; Psychedelics; SNRIs; Stimulants
Dangerous (29)
5-HTP, Tryptophan; Alpha-2 adrenergic receptor antagonist; Ephedrine, Pseudoephedrine; Local anesthetics; NRIs; Opioids; Antihistamines; Antipsychotics; Benzodiazepines, Barbiturates; Buspirone; Caffeine; Cannabis; Clonidine, Guanfacine; Dopamine agonists; DXM; GHB, Baclofen; GHB, GBL; Ibogaine; Ketamine, DXM, PCP; L-Tyrosine; Lithium; Naltrexone; NDRIs (Wellbutrin); NSAIDs; and 5 more, see full page
Caution (21)
See full page: psychedex.org/substances/2c-t-21
Not graded (4)
Not listed never means safe.

Seek help immediately if

Most difficulty is psychological (intense fear, panic, confusion) and passes with calm support — the signs below mean seek emergency help:

  • Very high body temperature; hot, dry skin
  • Seizures
  • Chest pain; fast or irregular heartbeat
  • Severe muscle rigidity, tremor, or twitching (possible serotonin syndrome)
  • Cold, pale, or blue fingers/toes — severe vasoconstriction (notably NBOMe / DOx)
  • Persistent vomiting; unconsciousness; uncontrollable agitation or risk of self-harm

What to do

  1. Stay calm and reassure — remind them they took a drug and the effect will pass
  2. Move to a calm, quiet, safe space with low light; reduce noise and sensory input
  3. Keep them from harm — they may act on fear or confusion; stay with them, don't leave them alone
  4. Talk them down gently; don't grab or restrain unless they're in danger
  5. For the medical signs above (overheating, seizure, chest pain, vasoconstriction, unresponsive) call emergency services
  6. If overheating, cool the body; be ready to give rescue breaths / CPR

The experience is time-limited and usually resolves with calm reassurance in a safe setting — psychological first aid, not medication. Serious physical harm is uncommon for classic psychedelics (LSD, psilocybin) but real for some potent phenethylamines (NBOMe, DOx), where hyperthermia, seizures, and vasoconstriction warrant emergency care.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

psychedex.org/substances/2c-t-21 · Version r1 · Not medical adviceValues as of
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