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1P-LSD (1-propionyl-LSD) is a semisynthetic lysergamide and one of the most widely distributed LSD prodrugs, differing from LSD only by a propionyl group on the indole nitrogen. Controlled studies show that this acylation reduces 5-HT2A affinity by one to two orders of magnitude, yet 1P-LSD retains roughly 38 percent of LSD's potency in the mouse head-twitch assay, an effect abolished by the selective 5-HT2A antagonist M100907; measurement of plasma LSD after dosing confirms efficient in vivo deacylation to LSD. Its subjective effects are therefore reported as near-indistinguishable from LSD, which underlies its popularity as a legal-grey substitute. It has become the most prevalent novel lysergamide in user surveys and has been extensively characterized by analytical, metabolic, and predictive toxicological methods.
- Prodrug of LSD; near-identical effects
- Widely available legal-grey lysergamide
- Very low physiological toxicity (LSD-like)
- Propionyl prodrug near-identical to LSD
- Anxiety or difficult experiences at higher exposure
- Raised heart rate, wide pupils
Mechanism
1P-LSD is a 1-propionyl derivative of LSD. The added group is believed to be removed by the body (hydrolysis), releasing LSD, so the downstream mechanism is the same: partial agonism at the receptor with additional serotonin and activity. Reported effects and duration closely track LSD, consistent with a that converts to it.
receptor fingerprint
receptoragonist (via conversion to LSD)
5-HT2C / receptorsagonist
Safetyrisks and cautions, not medical advice
Its safety profile is assumed to mirror LSD's given the prodrug relationship: physiologically low-toxicity but psychologically intense, with the same cautions. Avoid with MAOIs and strong serotonergics (serotonin toxicity) and with lithium or tramadol (seizure risk), and avoid entirely with a psychosis or bipolar history. As a newer research chemical, long-term human data are thin. Not medical advice.
Subjective profileweighing the evidence above
Effectively LSD with an extra step, so it deserves exactly the same seriousness rather than the casualness its legal-grey status invites. Physiologically forgiving, psychologically not. Off the table entirely with a psychosis or bipolar history, and never alongside MAOIs, lithium or tramadol.
Resources
No suppliers are provided for compounds like this. This entry is here for reference.
Research
- 2016first citedReturn of the lysergamides. Part I: Analytical and behavioural characterization of 1-propionyl-…
- 2020most active year3 papers
- 2026most recentThe toxicity of psychedelic LSD derivatives: 1-acetyl-LSD (ALD-52), 1-propionyl-LSD (1P-LSD), 1…
- 1.Pharmacological and biotransformation studies of 1-acyl-substituted derivatives of d-lysergic acid diethylamide (LSD)
- 2.Pharmacokinetics and subjective effects of 1P-LSD in humans after oral and intravenous administration
- 3.Return of the lysergamides. Part I: Analytical and behavioural characterization of 1-propionyl-d-lysergic acid diethylamide (1P-LSD).
- 4.In vitro metabolic fate of nine LSD-based new psychoactive substances and their analytical detectability in different urinary screening procedures.
- 5.The use patterns of novel psychedelics: experiential fingerprints of substituted phenethylamines, tryptamines and lysergamides.
- 6.The toxicity of psychedelic LSD derivatives: 1-acetyl-LSD (ALD-52), 1-propionyl-LSD (1P-LSD), 1-butyryl-LSD (1B-LSD), 1-valeryl-LSD (1V-LSD) and 1-cyclopropylmethanoyl-LSD (1cP-LSD)-prediction of toxicological parameters relevant to clinical and forensic toxicology using multi-in silico approach.
- 7.A highly sensitive UHPLC-MS/MS method for determining 15 designer LSD analogs in biological samples with application to stability studies.
- 8.Forensic Aspects of Designer LSD Analogs Identification by GC-MS (EI) and UV Spectroscopy.
- 9.Crystal Structure of an LSD-Bound Human Serotonin Receptor.
- 10.Structure of a Hallucinogen-Activated Gq-Coupled 5-HT2A Serotonin Receptor.
10 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Is it different from LSD?
Chemically it has an extra propionyl group, but the body is thought to cleave it back to LSD, so the experience is described as near-identical.
Why does it exist?
As a lysergamide research chemical it filled a legal-grey niche as an LSD substitute.
Same cautions as LSD?
Yes; avoid MAOIs/strong serotonergics, lithium, and tramadol, and avoid it with a psychosis or bipolar history.
Limitations of the evidence
- Thin long-term data as a newer research chemical
Adverse effects
- Anxiety or difficult experiences at higher exposure
- Raised heart rate, wide pupils