25B-NBOH, also known as 2C-B-NBOH or NBOH-2C-B, is a synthetic psychedelic from the phenethylamine family. It is an N-benzyl derivative of 2C-B and is closely related to 25B-NBOMe, although the two are different compounds. 25B-NBOH has been identified as a novel psychoactive substance in Europe, according to a forensic monograph, but research on its effects and toxicity in humans remains limited.
Chemistry
The structure of 25B-NBOH is based on 2C-B, with methoxy groups at the 2- and 5-positions and a bromine atom at the 4-position of the phenyl ring. Its distinguishing feature is a 2-hydroxybenzyl group attached to the nitrogen atom. This substitution places it in the NBOH family.
25B-NBOMe has a similar core structure, but carries a 2-methoxybenzyl group rather than the 2-hydroxybenzyl group found in 25B-NBOH. The difference is small on paper, but research on N-benzyl phenethylamines shows that changes to these substituents can affect receptor binding and functional activity.
Pharmacology
25B-NBOH is described as a potent serotonergic agonist, with activity reported at the 5-HT2A receptor. Research on N-benzyl phenethylamines has shown that adding a benzyl group to the nitrogen can substantially alter binding affinity and activity at 5-HT2A and 5-HT2C receptors. The exact contribution of each receptor to the effects of 25B-NBOH is not fully understood.
In a 2025 study of NBOH compounds in rodents, 25B-NBOH was tested alongside several related substances. It produced responses similar to DOM in rats trained to distinguish the psychedelic from other substances. The researchers also observed reduced spontaneous movement in mice. These are separate behavioural measures and do not establish how the compound affects people.
Subjective effects
The effects described in this section are drawn from user reports compiled in the 25B-NBOH profile on PsychonautWiki. They are anecdotal rather than findings from controlled human studies, and the source notes that the list is incomplete.
Physical effects
Stimulation is one of the most frequently described effects. It is often reported as a strong sense of energy without necessarily creating an urge to move. In some accounts, the stimulation becomes uncomfortable and is accompanied by shaking or jaw clenching.
Other reports describe a feeling of bodily lightness, sometimes approaching weightlessness, and a soft tingling sensation that may come in waves. An unpleasant metallic taste and numbness in the mouth are also mentioned.
Less comfortable physical effects include:
- Gastrointestinal: nausea, occasional vomiting and stomach cramps.
- Muscular: tension, cramps, contractions and restless legs.
- Cardiovascular: increased heart rate, abnormal heartbeat, elevated blood pressure and vasoconstriction.
- Temperature and hydration: increased body temperature, dry mouth and dehydration.
- Other: reduced appetite, changes in urination, pupil dilation and headaches.
Seizures are also included among the adverse effects reported in the available accounts. Their frequency and relationship to exposure have not been established.
Visual effects
Visual changes range from alterations in colour and detail to geometric patterns and more complex imagery.
Visual enhancements
Reported enhancements include stronger colour intensity, sharper visual detail and improved pattern recognition. Some accounts also describe a magnification effect, compared to looking through a fisheye lens, in which the apparent size of an object changes with the viewing angle.
Visual suppressions
Less commonly described changes include a perceived reduction in visual frame rate and difficulty interpreting information in peripheral vision.
Visual distortions
Surfaces may appear to drift, melt, flow, breathe or change shape. These distortions are described as relatively smooth and detailed, sometimes with a stylised or cartoon-like appearance. Other reports mention shifting colours, altered brightness, changes in depth and perspective, tracers, diffraction, afterimages, repeating symmetrical textures, recursive patterns and the apparent slicing of a scene.
Visual geometry
The geometric patterns are described as intricate, colourful and highly structured. Reports mention fine detail, sharp edges and a mixture of angular and rounded shapes. At greater intensity, patterns may seem to expand across the visual field and form an immersive, continuously changing environment.
Hallucinatory states
Reported experiences include transformations of objects and internal imagery such as settings, landscapes and scenes. More elaborate experiences are described less consistently. “Machinescapes” are mentioned as an uncommon type of imagery, generally associated in reports with particularly intense experiences.
Cognitive effects
Some users describe relatively clear thinking, with their usual train of thought largely intact. Faster thoughts and increased analytical activity are also reported, while abstract or conceptual thinking is sometimes described as less pronounced than with other psychedelics.
Other reported cognitive and emotional effects include:
- Anxiety and paranoia: both are reported, sometimes alongside a feeling of impending doom.
- Empathy and sociability: feelings of affection, closeness and sociability may occur, particularly in social settings, but are inconsistent.
- Emotional and sensory changes: increased emotional response, appreciation of music, immersion, novelty and humour; laughter fits are also mentioned.
- Thought and memory: accelerated thinking, altered sense of time and memory suppression. More intense accounts include confusion, amnesia and sensory overload.
- Other changes: increased wakefulness and libido, and a temporary reduction in personal bias.
Auditory effects
Reported auditory changes include enhanced hearing, sound distortions and occasional auditory hallucinations.
Multisensory effects
Some reports describe unexpectedly different levels of intensity between experiences. The reason for this variability is not known. Synesthesia, in which one type of sensory input is experienced through another, is also mentioned, but appears to be rare and inconsistent.
Transpersonal effects
Existential insights and a sense of unity or interconnectedness are occasionally reported. These experiences appear less consistent than the visual and physical effects.
Toxicity and harm potential
Human data on the toxicity of 25B-NBOH are limited, but a clinical case series published in 2022 provides direct evidence of serious poisoning. Five people were treated after exposure to a powder sold as LSD. One patient developed severe agitation, mydriasis, tachycardia and hypertension; another developed status epilepticus and required intubation. Both had acute kidney injury, and one also developed rhabdomyolysis. 25B-NBOH was detected in blood samples from the two more severely affected patients. Three other patients experienced mild hallucinations. The reported symptoms resolved within 12 hours.
This case series shows that exposure can cause serious acute effects, but it cannot establish how often they occur or define a reliable toxic range. Information about metabolism, longer-term effects and interactions is still sparse. A forensic monograph from the Center for Forensic Science Research and Education also records a 25B-NBOH detection in a US toxicology case and notes that the substance had appeared in Europe by June 2016.
Because 25B-NBOH is structurally related to 25B-NBOMe, comparisons between the two compounds are common. However, structural similarity does not prove that they have identical effects or toxicity.
Tolerance and dependence potential
User reports describe rapid tolerance and cross-tolerance with other psychedelics. Controlled studies of 25B-NBOH do not support estimates of how long tolerance takes to return to baseline. There is also insufficient clinical evidence to draw firm conclusions about its dependence potential.
Interactions
There are no controlled studies establishing a specific interaction profile for 25B-NBOH. Lithium, cannabis, stimulants and tramadol are listed in user-oriented interaction references as combinations of concern, but these warnings are not clinical findings specific to 25B-NBOH. Clinical literature on tramadol has reported seizures, including cases in which they occurred independently of dose.
History
Research on N-benzyl phenethylamines developed through laboratory studies of their activity at serotonin receptors. A 2014 study by Hansen and colleagues examined how changes to the phenethylamine and N-benzyl portions of these compounds affect binding and activity at 5-HT2A and 5-HT2C receptors. 25B-NBOH was identified in Europe as a novel psychoactive substance by June 2016, according to a forensic monograph.
Related compounds
Related substances include 25B-NBOMe, 25C-NBOH, 25I-NBOH and the parent compound 2C-B. They share parts of the same chemical framework, but differences in their substituents can affect their pharmacological properties. Their effects and risks should not be assumed to be interchangeable.
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