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25B-NBOMe is the N-(2-methoxybenzyl) derivative of 2C-B and one of the more potent members of the NBOMe family of hallucinogens. Addition of the 2-methoxybenzyl group produces a large increase in 5-HT2A receptor binding affinity, reaching sub-nanomolar values, and yields a high-efficacy agonist that drives the head-twitch response used as a rodent proxy for hallucinogenic activity. The compound undergoes extensive first-pass metabolism and is essentially inactive orally, so it is used sublingually and is commonly sold on blotter paper at very small doses. Its narrow margin between active and toxic doses has been reflected in analytically confirmed severe intoxications featuring agitation, seizures, hyperthermia, and rhabdomyolysis, and in vitro work additionally reports reactive-oxygen-mediated genotoxicity.
- Extremely potent, stimulating 5-HT2A agonist
- Radiolabeled form used as a research PET tracer
- Sub-nanomolar 5-HT2A binding affinity
- Severe vasoconstriction and high blood pressure
- Seizures, hyperthermia, and cardiac arrest
Mechanism
25B-NBOMe is 2C-B with a 2-methoxybenzyl group on the nitrogen; this modification vastly increases binding affinity and potency at the receptor, so much so that a radiolabeled version (Cimbi-36) is used as a PET tracer for that receptor in research. Its psychedelic and physiological effects flow from powerful 5-HT2A agonism, with additional 5-HT2C activity. The compound is destroyed in the gut, so it works only sublingually or by other non-oral routes.
receptor fingerprint
receptoragonist
5-HT2C receptoragonist
Safetyrisks and cautions, not medical advice
25B-NBOMe is active at extremely small amounts, so tiny errors in measurement can be dangerous, and its safety margin is very narrow. It can cause intense vasoconstriction, dangerously high blood pressure, seizures, severe agitation, hyperthermia, kidney injury, and cardiac arrest; multiple deaths have been reported. It must never be combined with stimulants, vasoconstrictors, or serotonergic drugs, and because it is frequently mis-sold as LSD, people should be aware that a blotter is not proof of what it contains. People with heart problems or a psychosis history should avoid it. Not medical advice.
Subjective profileweighing the evidence above
Genuinely dangerous, and that is the whole verdict. The gap between an active dose and a toxic one is tiny, deaths are documented, and it is routinely mis-sold as LSD so people take it without knowing. Its real use is as a lab tracer, not something anyone should put in their mouth.
Resources
This entry is here for reference.
Research
- 2014first citedSerotonin 2A receptor agonist binding in the human brain with [¹¹C]Cimbi-36
- 2015most active year4 papers
- 2020most recentNovel Psychoactive Phenethylamines: Impact on Genetic Material.
- 1.Toxicities associated with NBOMe ingestion-a novel class of potent hallucinogens: a review of the literature
- 2.Serotonin 2A receptor agonist binding in the human brain with [¹¹C]Cimbi-36
- 3.Receptor interaction profiles of novel N-2-methoxybenzyl (NBOMe) derivatives of 2,5-dimethoxy-substituted phenethylamines (2C drugs).
- 4.Comparative neuropharmacology of N-(2-methoxybenzyl)-2,5-dimethoxyphenethylamine (NBOMe) hallucinogens and their 2C counterparts in male rats.
- 5.Pharmacology and Toxicology of N-Benzylphenethylamine ("NBOMe") Hallucinogens.
- 6.Novel Psychoactive Phenethylamines: Impact on Genetic Material.
- 7.Metabolic fate and detectability of the new psychoactive substances 2-(4-bromo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25B-NBOMe) and 2-(4-chloro-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25C-NBOMe) in human and rat urine by GC-MS, LC-MS(n), and LC-HR-MS/MS approaches.
- 8.Two cases of severe intoxication associated with analytically confirmed use of the novel psychoactive substances 25B-NBOMe and 25C-NBOMe.
- 9.Analysis of 25I-NBOMe, 25B-NBOMe, 25C-NBOMe and Other Dimethoxyphenyl-N-[(2-Methoxyphenyl) Methyl]Ethanamine Derivatives on Blotter Paper.
- 10.Effects of the hallucinogen 2,5-dimethoxy-4-iodophenethylamine (2C-I) and superpotent N-benzyl derivatives on the head twitch response.
- 11.Prevalence of use and acute toxicity associated with the use of NBOMe drugs.
11 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
How is 25B-NBOMe different from 2C-B?
It is 2C-B with an N-methoxybenzyl group that makes it far more potent and much more dangerous.
Is it used in science?
Yes, a radiolabeled version called Cimbi-36 is used as a PET tracer to image the 5-HT2A receptor.
Why is it so risky?
It is active at tiny amounts, has a narrow margin, can cause seizures and heart problems, and is often sold as LSD.
Adverse effects
- Severe vasoconstriction and high blood pressure
- Seizures, hyperthermia, and cardiac arrest
Notes and cautions
- Very narrow safety margin
- Frequently mis-sold as LSD