Pethidine - Substance Search

Summary TheDrug.Wiki TripSit PsychonautWiki

Pethidine is significantly less safe than other opioids due to its toxic metabolite norpethidine, which accumulates with repeated dosing and can cause seizures, tremors, and CNS excitation. It should not be used for more than 48 hours or at doses exceeding 600 mg per 24 hours. The drug has a particularly high risk of serotonin syndrome compared to other opioids and should never be combined with MAOIs, SSRIs, or other serotonergic drugs.

Dose Information TheDrug.Wiki TripSit PsychonautWiki

ROA	Light	Common	Strong	Heavy
Oral	50-100mg	100-200mg	200-400mg	400mg+
Intramuscular	25-50mg	-	-	-
Intravenous	25-50mg	-	-	100+mg(extremecaution-rapidrespiratorydepression)+
Subcutaneous	25-50mg	-	-	-

Light Common Strong Heavy

Onset, Duration & After-effects TheDrug.Wiki TripSit PsychonautWiki

ROA	Onset	Peak	Offset	After Effects	Total
Oral	30-60 min	1-2 hrs	2-4 hrs	2-10 hrs	3.5-7 hrs
Intramuscular	10-15 min	30-60 min	1-2 hrs	1-6 hrs	1.7-3.2 hrs
Intravenous	1-5 min	5-10 min	1-2 hrs	1-6 hrs	1.1-2.2 hrs
Subcutaneous	10-20 min	30-60 min	1-2 hrs	1-6 hrs	1.7-3.3 hrs

Opioid MME Calculator

⚠ Citation & Disclaimer: Conversion factors sourced from the NIH HEAL Initiative MME Calculator (Adams et al., PAIN 2025), the CDC 2022 Clinical Practice Guideline for Prescribing Opioids for Pain, and the MDCalc MME Calculator. These are approximate equianalgesic ratios for educational reference only. Individual responses vary significantly based on genetics, tolerance, cross-tolerance, and route of administration. This is not medical advice. Do not use these conversions to adjust opioid dosing without professional medical guidance.

Convert from

mg

Convert to

100 mg Pethidine

≈

— mg Morphine

⚠ Equianalgesic dose ratios are approximations and do not account for genetic factors, tolerance, incomplete cross-tolerance, or pharmacokinetic variations. Methadone conversion is especially variable at higher doses. Always consult a healthcare provider before making any changes to opioid therapy.

Effect Profile

19 reports

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 7.6

Intense 8/10

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

Euphoria / Warmth ×3

10

physical euphoria cognitive euphoria euphoria mood lift

Analgesia ×2

8

pain relief analgesia

Sedation / Relaxation ×1

4

sedation dream potentiation

⚠ Itching / Nausea ×1

7

nausea constipation dry mouth

Based on reports from:

Erowid Experience Reports PsychonautWiki Pethidine

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 1d Half tolerance 21d Baseline ~35d

Effects Erowid

Aggregated from 19 Erowid experience reports

Positive Effects 8

Euphoria 31.6% 70%

Tactile Enhancement 26.3% 70%

Sedation 26.3% 70%

Stimulation 26.3% 70%

Empathy 21.1% 70%

Music Enhancement 21.1% 70%

Pain Relief 15.8% 70%

Focus Enhancement 15.8% 70%

Adverse Effects 3

Nausea 31.6% 70%

Headache 21.1% 70%

Confusion 21.1% 70%

Combinations TripSit

Pill Identifiers

12 known pill identifiers on record — view imprints, colors, shapes, and images

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Pethidine's nerd page Pharmacology, chemical data, effect profiles, and more

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Helpful Links

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