Ibotenic acid

2-amino-2-(3-oxo-1,2-oxazol-5-yl)acetic acid

Overview

Ibotenic acid belongs to Psychedelics.

Key safety note: Ibotenic acid is the neurotoxic, excitatory component of Amanita muscaria and A. pantherina.[4][3][5]
Effects
Subjective effects vary. What a substance feels like depends on dose, individual physiology, mindset, and setting. The points below describe commonly reported effects, not guaranteed, uniform, or desirable outcomes.
  • Amanita muscaria/pantherina intoxication, to which ibotenic acid contributes, is a deliriant and sedative-dissociative syndrome, not a classic psychedelic one: waves of drowsiness and dream-like or sleep-like states alternating with agitation.
  • Commonly reported: nausea and vomiting, muscle twitching or spasms, sweating and salivation, ataxia and loss of coordination, altered perception, sometimes euphoria, and retrograde amnesia for the episode.
  • The ibotenic-acid component specifically is associated with the more unpleasant, excitatory features (nausea, agitation and, at high doses or in children, seizures), while the muscimol formed from it drives the sedation and dissociation.
  • Onset is slow (about 2–3 hours) and effects last roughly 6–8 hours.
Dosing & duration
Harm-reduction note: These are commonly cited reference ranges, not a recommendation or a “safe” dose. Potency, purity, body chemistry, tolerance, and drug combinations vary widely. Start low, go slow, wait for full effects before redosing, and never assume an unknown product matches these figures. Missing data is not evidence of safety.

Oral. These figures are for isolated ibotenic acid and are not a recommendation. In practice ibotenic acid is consumed as Amanita muscaria/pantherina, whose ibotenic-acid and muscimol content varies enormously between mushrooms and regions. Drying or heating converts ibotenic acid to muscimol, so the effective dose from a given quantity of mushroom is highly unpredictable. Ibotenic acid is the more toxic, excitatory of the two components.

Dose ranges

Threshold (oral)

≈30–60 mg

Active (oral)

≈20–100 mg (50–100 mg ≈ 10–15 mg muscimol)

Duration

onset

≈2–3 h (slow)

total

≈6–8 h

Chemical & Physical Properties
FormulaC5H6N2O4
Molar mass158.11 g/mol
StateSolid (crystalline, commonly isolated as the monohydrate)
Melting point151–152 °C (anhydrous), 144–146 °C (monohydrate)
Boiling pointunavailable: true. reason: an amino-acid-type solid that decomposes on heating rather than boiling. No experimental boiling point is reported
Densityunavailable: true. reason: no reliable experimental value is reported for the crystalline solid
Vapor pressureNot reported
pKaNot reported
LogP-3.9 (predicted, XLogP3)
SolubilityWater: 1 mg/mL at 20 °C (free acid), 10.7 mg/mL in 0.1 M NaOH. 4.7 mg/mL in 0.1 M HCl
Refractive indexNot reported
Identifiers & Synonyms
CASNot reported
CAS (enantiomer)
PubChem CID1233
InChIKeyIRJCBFDCFXCWGO-UHFFFAOYSA-N
InChIInChI=1S/C5H6N2O4/c6-4(5(9)10)2-1-3(8)7-11-2/h1,4H,6H2,(H,7,8)(H,9,10)
SMILESC1=C(ONC1=O)C(C(=O)O)N

Synonyms

    Pharmacodynamics & Biochemistry

    Ibotenic acid is a conformationally restricted analogue of the excitatory neurotransmitter glutamate. It is a potent agonist at NMDA receptors and at group I/II metabotropic glutamate (mGlu) receptors, with weaker activity at AMPA and kainate receptors: a broadly glutamatergic, excitatory profile quite unlike that of the serotonergic psychedelics. This strong NMDA and glutamate-receptor activation makes ibotenic acid an excitotoxin: it can over-excite neurons to the point of calcium overload and cell death, which is exactly why it is used experimentally to create site-specific brain lesions. Ibotenic acid is best understood as a prodrug of muscimol: on heating (drying or cooking) and in the body it partly decarboxylates to muscimol, a potent GABA-A receptor agonist that produces most of the sedative, dream-like and dissociative effects of Amanita muscaria. Only roughly 10–20% is converted and much ibotenic acid is excreted unchanged, so the two co-occurring compounds pull in opposite directions: glutamatergic excitation versus GABAergic sedation. The best-characterised targets in quantitative receptor assays are the metabotropic mGlu1 and mGlu5 receptors, at which ibotenic acid is a full agonist (see the binding table). Firm quantitative constants for its ionotropic NMDA action are not established in our sources.

    Biological targets

    • NMDA
    • mGluR
    • AMPA

    Binding & functional measurements

    TargetMeasurementSpecies
    mGlu1 receptorpKi 6.15Rat
    Pharmacokinetics
    BioavailabilityOrally active, readily absorbed
    TmaxNot reported
    Half-lifeNot established in humans
    VdNot reported
    Protein bindingNot reported
    MetabolismPartial decarboxylation (~10–20%) to the active metabolite muscimol (promoted by drying/heating and occurring in vivo). Much of the dose is not converted
    ExcretionRenal, largely as unchanged ibotenic acid within hours
    Toxicology & Safety
    Harm-reduction note: Toxicity and risk depend on dose, route, purity, combinations, setting, and individual health factors. Missing harms should never be interpreted as evidence of safety.

    Not reported

    Ibotenic acid is the neurotoxic, excitatory component of Amanita muscaria and A. pantherina. As a potent NMDA/glutamate-receptor agonist it is an excitotoxin: able to kill neurons through over-excitation, the basis of its use to make experimental brain lesions, so it should not be regarded as a benign 'natural' psychoactive. Acute Amanita poisoning typically brings nausea and vomiting, agitation, muscle twitching, sweating, ataxia and drowsiness, with confusion, delirium and (especially in children or at high doses) seizures. A deep sedation or coma-like sleep can follow as ibotenic acid converts to muscimol. Because the ibotenic-acid and muscimol content of mushrooms varies enormously, and drying or heating shifts the balance toward muscimol, the effective dose from a given amount of mushroom is highly unpredictable. Serious poisonings occur. Medical help should be sought for anything beyond mild effects. Limited data must never be read as evidence of safety.[4][3][5]

    Legal Status
    Legal note: Legal status can change over time and may vary by country, region, formulation, analogue status, prescription context, and enforcement practice. Always confirm with current official sources before relying on this section.
    Interactions & Contraindications

    Drug interactions

    Alcohol, Benzodiazepines, Opioids The muscimol formed from ibotenic acid is a GABA-A agonist, so combinations with sedatives can deepen sedation and respiratory depression.[3]
    Drugs that lower the seizure threshold Its excitotoxic NMDA/glutamatergic action may add to seizure risk, particularly at high doses.[4]
    Anticholinergic drugs Additive confusion and delirium with other deliriants or anticholinergics.

    Contraindications

    Current or prior seizure disorder epilepsy or a lowered seizure threshold (excitotoxic glutamatergic action).[4]
    Combining with alcohol or other CNS depressants concurrent sedatives or other CNS depressants.[3]
    Children (age-restricted; respiratory-depression risk) children are more prone to ataxia and seizures during Amanita poisoning.[5]
    Pregnancy or breastfeeding
    Usage & Context
    • Traditional and contemporary use of Amanita muscaria ('fly agaric') and related Amanita mushrooms as an intoxicant and entheogen. Drying or heating is used to convert ibotenic acid to the less toxic muscimol.
    • Widely used in neuroscience as an excitotoxic agent to create site-specific brain lesions in laboratory animals.
    • Sold online as a research chemical or Amanita extract (noted 2023–2025).
    Sources & Evidence
    1. PubChem: Ibotenic acid (CID 1233) — identifiers & computed properties
    2. Wikipedia: Ibotenic acid (mechanism, effects, dosing & occurrence) CC BY-SA 4.0
    3. Rivera-Illanes D, Recabarren-Gajardo G (2024). Classics in Chemical Neuroscience: Muscimol. ACS Chem Neurosci 15:3257-3269.

      PMID 39254100 · doi:10.1021/acschemneuro.4c00304

    4. Schwarcz R, Hökfelt T, Fuxe K, et al. (1979). Ibotenic acid-induced neuronal degeneration: a morphological and neurochemical study. Exp Brain Res 37:199-216.

      PMID 40808 · doi:10.1007/BF00237708

    5. Hartwig J, Kendrick J, Ahmad G, et al. (2025). Exploring User Experiences with Amanita muscaria: A Thematic Analysis of Reddit Online Forum Discussions. Subst Use Misuse 60:952-961.

      PMID 40057818 · doi:10.1080/10826084.2025.2476141

    6. Liljefors T, Krogsgaard-Larsen P, Madsen U (2002). Textbook of Drug Design and Discovery, 3rd ed. CRC Press, p. 263 (ibotenic acid as an NMDA/mGlu glutamate-receptor agonist)
    7. Ott J (1996). Pharmacotheon: Entheogenic Drugs, Their Plant Sources and History, 2nd ed. (ibotenic acid–muscimol, Amanita use) CC BY-SA 4.0
    8. Thomsen C, Mulvihill ER, Haldeman B, et al. (1993). A pharmacological characterization of the mGluR1 alpha subtype of the metabotropic glutamate receptor expressed in a cloned baby hamster kidney cell line. Brain Res 619:22-8.

      PMID 7690672 · doi:10.1016/0006-8993(93)91592-g

    9. Mutel V, Ellis GJ, Adam G, et al. (2000). Characterization of [(3)H]Quisqualate binding to recombinant rat metabotropic glutamate 1a and 5a receptors and to rat and human brain sections. J Neurochem 75:2590-601.

      PMID 11080213 · doi:10.1046/j.1471-4159.2000.0752590.x

    10. IUPHAR/BPS Guide to PHARMACOLOGY (GtoPdb) CC BY-SA 4.0

    Further Information