25I-NBOMe: Complete Toxicology, Seizures, Hyperthermia, Fatalities & Safety Monograph

25I-NBOMe: Complete Toxicology, Seizures, Hyperthermia, Fatalities & Safety Monograph

Emergency warning: Severe agitation or confusion, seizure, dangerous overheating, chest pain, collapse, severe muscle rigidity/clonus, markedly abnormal blood pressure, or reduced consciousness after a suspected psychedelic can represent life-threatening toxicity. Emergency care should not wait for exact drug identification.

Quick answer

25I-NBOMe is a highly potent synthetic psychedelic in the N-benzyl phenethylamine (NBOMe) family and a strong serotonin 5-HT2A receptor agonist.

It is not LSD.

Its public-health significance comes from a combination of:

• very high receptor potency;
• tiny active quantities;
• frequent sale on blotter or as “acid”;
• severe stimulant/serotonergic toxicity;
• seizures and hyperthermia;
• rhabdomyolysis and kidney injury;
• analytically confirmed deaths;
• poor detection on routine toxicology screens.

The best-known clinical series involved seven analytically confirmed patients, all of whom developed tachycardia; six had agitation and hallucinations; three had seizures; three developed hyperpyrexia; all seven had elevated creatine kinase.

That toxicity profile is substantially more dangerous and physiologically complex than the common misconception that 25I-NBOMe is merely “strong LSD.”

Identity

History: from receptor research to recreational market

25I-NBOMe was developed as part of medicinal/receptor chemistry exploring high-affinity serotonergic ligands.

The compound also became known as CIMBI-5 in 5-HT2A receptor research. A radiolabeled form, [11C]CIMBI-5, was investigated as a PET ligand for imaging the active/high-affinity state of 5-HT2A receptors.

That scientific origin matters because it explains why the compound can be extremely potent at the receptor.

It does not mean the recreational drug has an established therapeutic use or safety profile.

By roughly 2010–2011, NBOMe compounds were appearing through online vendors and illicit markets. Within a few years, severe poisonings and deaths were being reported internationally.

Pharmacology

5-HT2A agonism

Classic psychedelic effects are strongly associated with 5-HT2A receptor activation.

Adding an N-benzyl group to a 2C phenethylamine can dramatically increase 5-HT2A affinity. 25I-NBOMe shows subnanomolar-range receptor affinity in experimental systems and potent agonist activity.

Additional receptor activity

25I-NBOMe can also interact with other serotonergic receptors.

The human clinical picture includes both:

• psychedelic perceptual effects;
• stimulant/serotonergic physiologic toxicity.

This is why severe cases can resemble serotonin toxicity plus sympathomimetic poisoning, rather than a simple prolonged psychedelic experience.

25I-NBOMe is not LSD

Both can produce hallucinations, but they are chemically and toxicologically different.

A piece of blotter paper does not tell you which compound is present.

Misrepresentation as “acid”

25I-NBOMe has repeatedly been sold as LSD.

Published fatal cases include people who believed they had taken “acid.”

This matters because someone expecting LSD may not anticipate:

• a different toxicity profile;
• severe vasoconstriction;
• seizures;
• hyperthermia;
• marked agitation;
• much greater product-dose sensitivity.

The correct harm-reduction principle is identity uncertainty, not instructions for distinguishing drugs by taste or other unreliable sensory tricks.

Analytically confirmed clinical toxicity

The landmark 2013 UK case series included seven young adult men with LC-MS/MS-confirmed 25I-NBOMe.

Clinical findings:

• tachycardia: 7/7;
• agitation: 6/7;
• visual/auditory hallucinations: 6/7;
• hypertension: 4/7;
• seizures: 3/7;
• hyperpyrexia: 3/7;
• clonus: 2/7;
• metabolic acidosis: 3/7;
• acute kidney injury: 1/7;
• elevated creatine kinase: 7/7.

The cases establish a severe human toxidrome with overlapping serotonergic, sympathomimetic, neurologic and muscle-injury features.

Seizures

Seizures are among the best-documented severe complications.

They can worsen:

• hyperthermia;
• lactic/metabolic acidosis;
• muscle injury;
• aspiration risk;
• cerebral hypoxia.

A seizure after suspected NBOMe exposure is a medical emergency.

Hyperthermia and rhabdomyolysis

Dangerous overheating can result from:

• serotonergic activation;
• agitation;
• muscle activity;
• seizures;
• vasoconstriction;
• environmental conditions.

Rhabdomyolysis—breakdown of skeletal muscle—appears repeatedly in NBOMe toxicity literature.

Complications can include:

• markedly elevated creatine kinase;
• acute kidney injury;
• electrolyte disturbance;
• secondary organ injury.

This is one reason severe NBOMe poisoning cannot be reduced to “a bad trip.”

Serotonin toxicity features

Published cases can include:

• agitation;
• hyperthermia;
• clonus;
• autonomic instability;
• neuromuscular abnormalities.

Not every toxic NBOMe presentation necessarily meets formal serotonin-syndrome criteria.

The safest wording is that serotonergic toxicity is an important clinical mechanism, and severe cases can resemble serotonin syndrome.

Vasoconstriction and cardiovascular toxicity

Potential findings include:

• tachycardia;
• hypertension;
• peripheral vasoconstriction;
• chest pain;
• cardiovascular stress.

Severe agitation and hyperthermia add additional cardiac demand.

There is no validated consumer blood-pressure or heart-rate threshold that makes use “safe.”

Fatalities

Two fatal cases with deeper toxicology required

A 2014 forensic report described two deaths associated with 25I-NBOMe.

Routine comprehensive toxicology initially found little beyond marijuana exposure.

Time-of-flight mass spectrometry and subsequent tandem-MS confirmation were required to identify 25I-NBOMe.

The cases involved violent agitation, collapse and significant external injuries.

Washington State fatal case

A separate analytically confirmed Washington State death involved a 15-year-old who reportedly used 25I-NBOMe, developed vomiting and seizures, and subsequently died.

What fatality reports can and cannot tell us

They establish:

• real lethal potential;
• routine-screen limitations;
• severe neurologic/toxicologic complications.

They do not establish:

• a universal fatal dose;
• a safe dose below the reported amount;
• a universal lethal blood concentration.

Why blood concentration is difficult to interpret

NBOMe compounds are active at very low exposures, and measured concentrations can be tiny.

Interpretation depends on:

• sampling time;
• route;
• redistribution;
• survival interval;
• co-drugs;
• tolerance;
• laboratory sensitivity;
• specimen type.

A concentration from a fatality is not a personal dose calculator.

Metabolism

25I-NBOMe undergoes extensive metabolism.

Common pathways include:

• O-demethylation;
• hydroxylation;
• N-dealkylation;
• combinations of those reactions;
• subsequent conjugation.

CYP enzymes

Human-liver-microsome work found important roles for:

• CYP2D6;
• CYP3A4;

with additional enzyme contributions.

This creates plausible interaction potential with drugs that inhibit or induce relevant enzymes, although the clinical magnitude has not been well quantified.

Toxicology biomarkers

Major metabolites identified in human-liver studies have also been found in authentic blood and urine.

Metabolite targets can improve detection because:

• parent compound may be present at very low concentration;
• parent may have declined by the time of sampling;
• routine assays often do not include NBOMe compounds.

Drug testing

Routine screens can be negative

25I-NBOMe is not reliably detected by ordinary workplace or emergency immunoassay panels.

Published fatal cases demonstrate that routine broad toxicology can miss it.

Definitive methods

Identification commonly relies on:

• LC-MS/MS;
• LC-HRMS/QTOF;
• validated targeted methods;
• exact-mass screening;
• parent drug plus metabolites.

Expanded NPS libraries are especially important when the reported drug (“LSD,” “acid”) does not fit the clinical presentation.

Product testing and counterfeit risk

A blotter or powder can contain:

• 25I-NBOMe;
• another NBOMe;
• a different NBOH compound;
• LSD;
• another psychedelic;
• multiple substances.

Visual appearance is not sufficient chemical identification.

This page intentionally avoids sensory-identification tricks because they are unreliable and can create false reassurance.

Interactions

Controlled 25I-NBOMe interaction studies are sparse.

Highest theoretical/clinical concern includes:

• other serotonergic drugs;
• monoamine oxidase inhibitors;
• stimulants;
• drugs that increase body temperature or cardiovascular load;
• substances that impair judgment or delay recognition of toxicity.

An interaction table cannot prove that a combination is safe.

Tolerance

Classic psychedelics can produce rapidly developing pharmacodynamic tolerance through serotonergic receptor adaptation.

25I-NBOMe-specific controlled human tolerance studies are not available.

Therefore tolerance is biologically plausible, but the exact onset, magnitude and cross-tolerance with LSD/other psychedelics are not well quantified clinically.

Physical dependence, addiction and withdrawal

What is not established

There is no well-defined 25I-NBOMe physical-dependence syndrome comparable with:

• opioids;
• benzodiazepines;
• alcohol.

There is also no validated NBOMe withdrawal timeline.

Addiction liability

The literature does not provide a good population estimate of 25I-NBOMe use disorder.

Classic serotonergic psychedelics generally have lower compulsive-use liability than strongly reinforcing stimulants or opioids, but that broad class observation should not be converted into “25I-NBOMe cannot become problematic.”

Possible harms from repeated use can still include:

• escalating risk-taking;
• psychiatric destabilization;
• repeated toxic exposures;
• persistent perceptual symptoms in susceptible people.

Persistent psychiatric/perceptual effects

Case literature on NBOMe compounds includes prolonged psychiatric symptoms in some patients.

Potential concerns include:

• persistent anxiety;
• psychosis in vulnerable individuals;
• prolonged perceptual disturbance.

The incidence and causal specificity for 25I-NBOMe are not well established.

Acute treatment principles

There is no specific approved antidote for 25I-NBOMe.

Published severe cases were managed with supportive emergency care, including treatment of:

• agitation;
• seizures;
• hyperthermia;
• blood-pressure abnormalities;
• rhabdomyolysis;
• renal/metabolic complications.

Benzodiazepines have been used clinically for agitation/seizure control in NBOMe poisoning, but this page does not provide a home-treatment or dosing protocol.

Severe toxicity belongs in emergency medical care.

Forensic interpretation

Detection vs causation

If 25I-NBOMe is detected in a death, interpretation still considers:

• co-drugs;
• trauma;
• hyperthermia;
• seizure complications;
• underlying disease;
• specimen type;
• scene history.

Negative routine toxicology does not exclude it

The early fatal cases are a classic example of why novel psychoactive substances can require expanded methods.

No universal fatal level

The compound's high potency, low measured concentrations and variable clinical course make a single “fatal blood concentration” scientifically inappropriate.

Special populations

Controlled data are inadequate for:

• pregnancy/breastfeeding;
• adolescents;
• older adults;
• cardiovascular disease;
• seizure disorders;
• bipolar/psychotic disorders;
• significant liver/kidney disease.

Adolescents are not theoretical: published fatal cases include teenagers.

Legal and regulatory history

United States

DEA temporarily placed 25I-NBOMe, 25C-NBOMe and 25B-NBOMe in Schedule I effective November 15, 2013.

Following the permanent scheduling process, those controls became permanent in 2016.

25I-NBOMe remains a federal Schedule I controlled substance.

International

25I-NBOMe was placed in Schedule I of the 1971 Convention on Psychotropic Substances in 2015.

UNODC continues to list it as internationally controlled.

Myths and misconceptions

“25I-NBOMe is basically stronger LSD.”
False. It is a different chemical class with a different and more dangerous severe-toxicity profile.

“If it is on blotter, it is probably LSD.”
False. Blotter is a dosage form, not chemical identification.

“A negative routine drug screen rules out NBOMe.”
False. Targeted/high-resolution testing may be required.

“Serotonin syndrome is the only risk.”
No. Seizures, hyperthermia, rhabdomyolysis, kidney injury, vasoconstriction, trauma and cardiovascular complications also matter.

“A fatal concentration tells me a lethal dose.”
False. Blood concentration and ingested dose are not interchangeable.

“Because classic psychedelics are not usually physically addictive, 25I-NBOMe is safe to repeat.”
False. Low physical-dependence evidence does not erase acute toxicity.

Evidence ledger

Related evidence

• RC psychedelics, tryptamines & lysergamides
• 2C-B-FLY
• 1P-LSD
• 1cP-LSD
• AL-LAD
• 4-AcO-DMT
• 5-MeO-MiPT
• Substance Use, Dependence & Harm Reduction hub

Bottom line

25I-NBOMe is one of the clearest examples of why “psychedelic” does not automatically mean physiologically benign.

Its evidence base includes analytically confirmed seizures, hyperthermia, rhabdomyolysis, renal injury and deaths; its potency makes product variation consequential; and its history of being sold as LSD creates a major identity hazard.

The most useful safety message is not a potency chart. It is accurate identification, recognition of severe toxicity, early emergency care, and refusal to treat a blotter appearance or negative routine screen as proof of what drug is present.