Alfentanil - Substance Search

Summary TheDrug.Wiki

Alfentanil is a short-acting synthetic opioid analgesic approximately one-quarter to one-tenth the potency of fentanyl, with a rapid onset (1-2 minutes) and brief duration (30-60 minutes). Almost exclusively used in controlled medical anesthesia settings for surgical procedures requiring precise, short-term analgesia. Carries extreme risk of life-threatening respiratory depression, particularly when combined with other CNS depressants.

Dose Information TheDrug.Wiki

Light Common Strong Heavy

Onset, Duration & After-effects TheDrug.Wiki

ROA	Onset	Comeup	Peak	Offset
Intravenous	1-2 min	2-5 min	5-15 min	15-30 min

Effect Profile

Scores (1–10) curated from multiple sources:

Effect keyword matching from PsychonautWiki catalog
Weighted by importance: core (×3), major (×2), minor (×1)

Full methodology

Opioid 6.1

Strong 6/10

Strong euphoria and itching/nausea with mild sedation and pain relief

Euphoria / Warmth ×3

10

physical euphoria euphoria cognitive euphoria warmth mood lift

Analgesia ×2

4

pain relief

Sedation / Relaxation ×1

5

sedation muscle relaxation

⚠ Itching / Nausea ×1

10

itching nausea constipation

Based on reports from:

Erowid Experience Reports PsychonautWiki Alfentanil

Tolerance

Build-up develops within days of regular use; analgesic tolerance faster than respiratory depression tolerance

Reset 7–14 days for partial reset; full reset may take weeks — tolerance loss greatly increases overdose risk

Tolerance Decay

Full tolerance 7d Half tolerance 3d Baseline ~14d

Opioid tolerance to sedative/analgesic effects typically develops over days to weeks and decays over days to weeks after cessation; interindividual variability is high. Cross‑tolerance among µ‑agonists is substantial but not complete. Values here are approximations synthesized from clinical experience and reviews rather than alfentanil‑specific PK/PD studies.