Amantadine

An antiviral and antiparkinson medicine, FDA-approved for Parkinson's disease, dyskinesia, drug-induced movement reactions and influenza A (older uses).

psilodex.org/m/amantadine · data v2026.10.05

Clinical contraindication: None listed; No label contraindication covering psilocybin was found. This is not a finding that the combination has been shown to be without risk.
Psilocybin evidence: No psilocybin data
Half-life: ~16 h; Approximate, in adults. Source under Interaction below.

Named in state rules?

Not namedColorado Condition rules (4)

Not namedOregon

PendingNew Mexico

Cite asPsilodex, “Amantadine”, v2026.10.05. psilodex.org/m/amantadine

Clinical data and state rules are separate facts. Both are shown; neither is a decision.

What it is used for

FDA status

FDA-approved

FDA-approved for

Parkinson's disease and parkinsonism
Dyskinesia in Parkinson's disease on levodopa (Gocovri)
"Off" episodes in Parkinson's disease (Gocovri, add-on to levodopa/carbidopa)
Drug-induced extrapyramidal reactions
Influenza A prevention and treatment

Sources [1][2]

01 Interaction with psilocybin

Not studied with psilocybin; amantadine can cause hallucinations and confusion, so added perceptual effects are possible.

Detail Amantadine has not been studied with psilocybin. It is a weak NMDA receptor blocker with anticholinergic-like effects (blocking acetylcholine). Hallucinations and confusion are labeled effects that may add to psilocybin's perceptual effects. Also, labels also report suicidality, falling asleep during daily activities, and orthostatic hypotension (a blood pressure drop on standing). They also report increased seizure activity in people with epilepsy. Stopping it suddenly can bring parkinsonian crisis or an NMS-like reaction (a severe fever-and-rigidity reaction). Sources [1]

Human data with psilocybin: No psilocybin data; based on how it works and its label
Half-life: ~16 h (FDA label, checked 2026-10-04) Steady state (Gocovri); IR label reports 17 ± 4 h.

Evidence types on this record

No psilocybin dataNo psilocybin data: no human data with psilocybin or another classic psychedelic; the text draws on the medication's own pharmacology and its label or reference facts

02 Pharmacology relevant to psilocybin

6 listed · counted on reports

Anticholinergic: Blocks acetylcholine. Can cause a fast heart rate, dry mouth, reduced sweating and heat intolerance, and confusion, more so at high doses or in combination. Sources [2]
Sedating or CNS depressant: Slows the central nervous system: drowsiness, slower reactions and impaired coordination, and slowed breathing at high doses. Effects add with other sedating substances. Sources [1]
Withdrawal or rebound if stopped abruptly: Stopping suddenly can cause withdrawal or a rebound of symptoms. Sources [2]
Lowers blood pressure or causes orthostasis: Lowers blood pressure, or causes a drop on standing (orthostasis) that can bring dizziness or fainting. Sources [1]
Psychiatric reactions: The label or source warns of psychiatric effects such as psychosis, mania, hallucinations, suicidal thoughts or severe mood or behavior changes. Psilocybin can also bring up strong emotions, so these warnings are relevant to screening. Sources [1]
Lowers seizure threshold or carries seizure risk: Makes a seizure more likely, or has been linked to seizures. Sources [2]

03 State rules

Plain-language summary · official text governs

CO4 CCR 755-1

Not namedCondition rules (4)

No provision names this medication or its class.

Colorado · checked 2026-10-04

OROAR 333-333

Not named

No provision names this medication or its class.

Oregon · checked 2026-10-04

NM7.35.3 NMAC (proposed)

Pending

New Mexico's clinical rules (proposed 7.35.3 NMAC) are not final. No provision naming this medication has been found.

New Mexico · checked 2026-10-04

04 Conditions to ask about

Screening items in state rules

This medication is usually taken for a condition. State rules screen for some conditions directly, so the medication is a prompt to ask about them. Confirm with the participant; never assume a condition from the medication.

Parkinson's disease (severe chronic illness)
- CO 2.5(A)(2) · Clinical Facilitator licensees
- CO 6.16(F)(2)(a) · Facilitators without a clinical facilitator license
- CO 6.16(F)(1) · All licensees
Antipsychotic-induced movement side effects (indication; antipsychotic use possible)
- CO 2.2(A)(6)–(7) · Facilitator licensees

05 Sources

GOCOVRI (amantadine) extended-release capsules (Supernus) · FDA label (DailyMed) — Sedating or CNS depressant: 5.1 "Patients treated for Parkinson's disease have reported falling asleep while engaged in activities of daily living, including the operation of motor vehicles, which sometimes has resulted in accidents." | Psychiatric reactions: 5.2 "In controlled clinical trials, suicidal ideation or suicide attempt was reported in 2% of GOCOVRI-treated patients and 0% of placebo-treated patients." | Lowers blood pressure or causes orthostasis: 5.4 "In controlled clinical trials, 29% of GOCOVRI-treated patients and 2% of placebo-treated patients experienced dizziness, syncope, orthostatic hypotension, presyncope, postural dizziness or hypotension." | 12.1 "Amantadine is a weak uncompetitive antagonist of the NMDA receptor." | 12.3 "The mean plasma amantadine half-life at steady-state was approximately 16 hours."
AMANTADINE HYDROCHLORIDE capsules (Strides) · FDA label (DailyMed) — Anticholinergic: Precautions "The dose of anticholinergic drugs or of amantadine should be reduced if atropine-like effects appear when these drugs are used concurrently." | Lowers seizure threshold or carries seizure risk: Warnings, CNS Effects "Patients with a history of epilepsy or other "seizures" should be observed closely for possible increased seizure activity." | Withdrawal or rebound if stopped abruptly: Precautions "Amantadine should not be discontinued abruptly in patients with Parkinson's disease since a few patients have experienced a parkinsonian crisis, i.e., a sudden marked clinical deterioration, when this medication was suddenly stopped."

Record history

v2026.10.02First published.
2026-10-04Last reviewed against its sources.

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