People use the word “psychedelic” for a crowd of very different chemicals, and conflating them is the most common error in this whole area. This cluster sorts them out at the level of what each compound is — its chemical class, its main receptor target, and what research actually covers — without telling anyone which to use. Two substances dominate real microdosing: psilocybin and LSD, with psilocybin the most documented. [1] Systematic review The emerging science of microdosing: A systematic review of research on low dose psychedelics (1955-2021) and recommendations for the field doi:10.1016/j.neubiorev.2022.104706 The classic psychedelics share a serotonergic 5-HT2A mechanism; [2] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478 the substances people confuse with them, such as ketamine and MDMA, work through entirely different pathways. Across almost all of them, the compound is described far better than its microdosing evidence. [3] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204 The cluster’s anchor: knowing what a substance is — its class, its receptor target, what has been studied — is not the same as knowing it works at a microdose; for almost everything except psilocybin and LSD, the compound is described far better than its microdosing evidence.
This is an education-only research overview, not sourcing, dosing, medical, or legal advice. It describes what these compounds are and what research reports about them. It does not tell you which substance to choose or use, where to obtain anything, how much to take, or whether any substance is safe or legal for you. Dosing belongs to the protocols material, risk to the safety cluster, and legality is covered separately. For personal decisions about your health or medications, talk to a qualified clinician.
A research-literacy map, not a selection guide. This cluster is not a guide to choosing, substituting, combining, or using psychedelic substances. It explains how different compounds are classified, how their evidence bases differ, and why findings from one substance cannot be automatically transferred to another. It does not address sourcing, legality by jurisdiction, preparation, dosage, or instructions for use.
Why “the substance” is its own question
The word psychedelic does not identify a single intervention. It groups together substances with different chemistry, duration, pharmacology, risk profiles, and research coverage. Most pages about psychedelics blur three further questions together: what is this molecule, how does it work in the brain, and should I take it. This cluster answers only the first. It is the identity layer — the place to find out that psilocybin and LSD are chemically unrelated despite acting on the same receptor, that ayahuasca is a preparation rather than a single drug, and that ketamine is not a psychedelic in the pharmacological sense at all.
Keeping identity separate from mechanism and from dosing is what makes accurate reading possible. A claim like “psychedelics improve mood” hides the fact that the evidence behind it is almost entirely psilocybin and LSD, at full doses, in screened volunteers. Naming the specific compound, its class, and what was actually studied is the difference between an informed reader and a marketed one.
| This cluster (Substances) | Covered elsewhere |
|---|---|
| What a compound is: class, structure family, main target | How the mechanism works in the brain (How It Works) |
| What research has and has not examined for each | How much and how often to take (Protocols) |
| Why pharmacologically different drugs are not interchangeable | The mushroom material, species, and potency (Mushroom Intelligence) |
| Research-reported descriptions of the landscape | Risk, contraindications, and adverse events (Safety) |
| — | Whether a substance is legal where you are (Legal Status) |
The classic psychedelics: one mechanism, several chemistries
The “classic” or serotonergic psychedelics are defined by a shared mechanism: agonist activity at the serotonin 5-HT2A receptor. [2] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478 What is easy to miss is that they belong to different chemical families. Psilocybin and DMT are tryptamines, structurally related to serotonin itself. LSD is an ergoline, a more complex molecule derived from ergot alkaloids. Mescaline is a phenethylamine, the same broad family as the stimulants and MDMA. So “classic psychedelic” is a pharmacological category, not a chemical one.
| Compound | Chemical family | Main target | Microdosing evidence base |
|---|---|---|---|
| Psilocybin | Tryptamine | 5-HT2A agonist | Largest — most surveys and the few trials |
| LSD | Ergoline | 5-HT2A agonist | Second — including self-blinding studies |
| DMT / ayahuasca | Tryptamine | 5-HT2A agonist | Minimal — rarely microdosed |
| Mescaline | Phenethylamine | 5-HT2A agonist | Essentially none |
These compounds rank low on standard drug-harm measures relative to many legal and illegal substances, [4] Peer-reviewed Drug harms in the UK: a multicriteria decision analysis doi:10.1016/S0140-6736(10)61462-6 but a low harm ranking is a statement about populations and full doses, not a safety clearance for any individual or for repeated microdosing — that distinction lives in the safety cluster, not here.
The substances people confuse with psychedelics
A second group gets lumped in by the public but is pharmacologically distinct. Ketamine is a dissociative anaesthetic acting on the NMDA receptor — a different system entirely. MDMA primarily releases serotonin, dopamine, and noradrenaline rather than acting as a receptor agonist, and its subjective profile is neither stimulant nor classic hallucinogen. Ibogaine has a complex multi-receptor profile and a serious cardiac risk signal. None of these is a serotonergic psychedelic, and microdosing claims built on psilocybin or LSD do not transfer to them. The atypical and adjacent substances page treats this in detail.
The microdosing evidence is concentrated, not spread
It is tempting to assume that because psychedelics as a group attract research, every individual substance is well studied at microdose level. It is not so. A systematic review of low-dose psychedelic research found the field thin and dominated by uncontrolled self-report even for the best-studied substances. [1] Systematic review The emerging science of microdosing: A systematic review of research on low dose psychedelics (1955-2021) and recommendations for the field doi:10.1016/j.neubiorev.2022.104706 A field overview framed microdosing as having “more questions than answers,” with most basic pharmacology of repeated low doses still unmapped. [3] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204 What evidence exists is overwhelmingly psilocybin and LSD; for the rest, the honest description is “studied at full dose, for other reasons, not at a microdose.”
Compound-specific evidence matters
A microdosing claim should be tied to the compound that was actually studied. Evidence from psilocybin does not automatically apply to LSD. Evidence from LSD does not automatically apply to mescaline, DMT, or research chemicals. And evidence from full-dose psychedelic research does not automatically apply to sub-perceptual repeated dosing. A substance can be psychedelic, serotonergic, or culturally associated with microdosing without ever having been studied as a microdosing intervention. Put plainly: a shared label is not shared evidence.
Classification is not validation
Knowing a substance’s category tells you something about its pharmacology and almost nothing about whether it has microdosing evidence. The label is a starting point for understanding, not a credential.
| Label | What it can tell you | What it cannot tell you |
|---|---|---|
| Classic psychedelic | Usually serotonergic 5-HT2A activity | Whether it has microdosing evidence |
| Dissociative | Different pharmacology from classic psychedelics | That microdosing claims transfer to it |
| Entactogen / empathogen | Social-emotional pharmacology, often monoamine release | That it behaves like psilocybin |
| Naturally occurring | Origin or cultural context | Safety, potency, or efficacy |
| Research chemical | Often limited formal human data | Safety or predictability |
Evidence transfer is the central problem
The more two substances differ in chemistry, receptor profile, dose range, duration, preparation, and research context, the less defensible it is to transfer findings from one to the other. Even substances within the same broad family require compound-specific evidence when the claim is about a specific practice such as microdosing. Similar receptor targets do not make two substances interchangeable interventions — duration, potency, receptor profile, pharmacokinetics, dose precision, context, and evidence base can all differ. This single principle is the reasoning the rest of the cluster rests on.
A map of the cluster
| You are asking about | Read |
|---|---|
| Psilocybin as a molecule (vs the mushroom) | Psilocybin, the compound |
| LSD and what its research examines | LSD and microdosing |
| How the classic psychedelics compare | Classic psychedelics compared |
| DMT, ayahuasca, mescaline, peyote, San Pedro | Other classic psychedelics |
| Ketamine, MDMA, ibogaine | Atypical and adjacent substances |
| ”Research chemicals” and novel compounds | Novel and research chemicals |
| What the evidence base actually covers | What the research covers |
For how the mechanism works, see How It Works; for the mushroom material and its potency, Mushroom Intelligence; for how much and how often, Protocols; and for risk, the Safety overview. For how to weigh any of these claims, see how to read microdosing claims; for combining substances with medications, the interactions overview.
- Class ≠ chemistry
- ”Classic psychedelic” is a mechanism category (5-HT2A agonism); within it sit unrelated chemical families — tryptamines, ergolines, phenethylamines. [2] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478
- Studied ≠ studied at a microdose
- A compound can be well characterised pharmacologically and have almost no controlled microdosing evidence. [3] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204
- Psychedelic ≠ everything mind-altering
- Ketamine and MDMA are widely called psychedelics but work through different systems; psilocybin and LSD claims do not transfer to them.
- Description ≠ recommendation
- This cluster says what each compound is, never which to use, source, or dose.
Frequently asked questions
What substances are actually used for microdosing?
In practice and in the research literature, two: psilocybin (from mushrooms) and LSD. Almost all microdosing studies and surveys describe one or the other, with psilocybin the most documented. [1] Systematic review The emerging science of microdosing: A systematic review of research on low dose psychedelics (1955-2021) and recommendations for the field doi:10.1016/j.neubiorev.2022.104706 Everything else people associate with psychedelics — DMT and ayahuasca, mescaline, ketamine, MDMA, ibogaine — is either rarely microdosed, pharmacologically different, or studied at full doses for entirely different purposes. This cluster describes what each compound is, not which to take; choosing or dosing a substance is out of scope and dose-related questions belong to the protocols material.
Is this cluster going to tell me which substance is best?
No. It is a description layer, not a recommendation engine. It explains what each compound is — its chemical class, its main receptor target, and what research has and has not examined — so you can read claims more accurately. It does not rank substances, tell you which to use, or suggest one is safer or more effective than another, because those are dosing, medical, and legal judgements a webpage cannot make for an individual. Where a question is really about risk, mechanism, the mushroom material, or legality, it points you to the cluster that covers it.
Does a substance being studied mean it works at a microdose?
No, and this is the central distinction the cluster holds. Most psychedelic research uses full, perceptual doses in screened clinical settings; that evidence does not transfer downward to sub-perceptual microdoses. [3] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204 A compound can be well characterised pharmacologically and still have essentially no controlled microdosing evidence. Knowing what a substance is tells you very little about whether a microdose of it does anything — for almost everything except psilocybin and LSD, the compound is described far better than its microdosing evidence.
Where does this cluster stop and another begin?
This is the “what is this compound” layer. How a substance acts on receptors is covered in How It Works; the mushroom material itself, its species and potency, is Mushroom Intelligence; how much and how often is Protocols; who studies it and how to interpret results is Experience Levels and Foundations; risk and contraindications are Safety; and legality is covered in Legal Status. This page describes identity and class and routes everything else to the right place.
Are all psychedelics interchangeable for microdosing?
No. Compounds differ in chemistry, receptor profile, duration, dose precision, safety considerations, and evidence base. Findings from one substance should not be transferred automatically to another. [3] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204 A substance can be a classic psychedelic and still have little or no direct microdosing evidence, and two substances that share a receptor target can behave very differently in practice. [2] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478 The cluster’s controlling idea is that compound identity matters and evidence does not transfer by category label.