Substance-Specific Neurological Risks

Urgent help first

A seizure, collapse, sudden loss of balance or coordination, severe confusion or trouble breathing is an emergency. In the US call 911. For a possible poisoning, Poison Help is 1-800-222-1222 (see poisoning: what to do first). This page is education only and does not suggest using, combining or stopping anything.

How to read this page

Neurological risks differ sharply between substances, so they are listed one at a time. A finding for one substance does not apply to another. Evidence labels used: approved medicine, established, mixed, insufficient evidence, preclinical (cells/animals only), evidence of harm.

Ibogaine

Ibogaine is a compound from the West African shrub Tabernanthe iboga (see ibogaine); it is distinct from the whole plant and traditional preparations.

Humans. In 14 people with opioid use disorder given ibogaine, cerebellar effects (problems with balance and coordination, called ataxia) and heart-rhythm changes appeared to be driven more by ibogaine than by its breakdown product noribogaine, and clearance varied strongly with a CYP2D6 gene. [1] UK poison service data on seven patients recorded convulsions, coma and stupor among the features, alongside heart problems. [2] A review of 19 deaths found that the clinical and postmortem evidence did not suggest a characteristic syndrome of neurotoxicity, and noted seizures linked to withdrawal from alcohol and benzodiazepines as an apparent risk factor. [3] The heart side is on cardiovascular risks.

Animals. In rats, a single high dose caused degeneration of Purkinje cells (nerve cells in the cerebellum), while a lower dose in one experiment did not. [4] A dose-response study found the damage was dose-related. [5] A toxicology review notes these findings were in rats and probably involve overstimulation of a brain region called the inferior olive. [6] Animal findings must not be read as proof of the same harm in people; the human review above found no characteristic neurotoxicity pattern. [3] Label: preclinical for Purkinje findings.

Classic psychedelics and seizures

A 2024 scoping review of 16 human and 11 animal publications found mixed results that globally suggest psychedelics may not increase seizure risk in healthy people or animals when no other drugs are involved. It found that other substances, such as kambo or lithium, could raise risk, and warned the data have limited external validity. [7] Online reports linked lithium plus classic psychedelics with seizures in 47% of 62 reports (unverified, not clinical data). [8] The authors note that studies of these substances tend to exclude people with a history of epilepsy, so no conclusion for people with epilepsy can be drawn. [7] Label: mixed.

Salvia divinorum

In a laboratory study of its active compound salvinorin A in four healthy adults, effects included changes in spatial orientation and pressure on the body, lasted around 20 minutes, and did not significantly raise heart rate or blood pressure. [9] A review of animal studies found a lack of evidence of short- or long-term toxicity, and said much more investigation is needed. [10] A review and case series hypothesized that use may be associated with psychotic disorders. [11] Proper evidence not found for seizures or lasting nerve damage in humans. See Salvia divinorum and psychosis vulnerability.

Ketamine: bladder and memory

NIDA says ketamine use can cause ketamine-induced uropathy, a treatable but potentially serious condition with symptoms like a urinary tract infection, and that long-term heavy use is associated with memory problems. [12] A 2022 meta-analysis of 45 articles (4,921 patients) found frequent urination (pooled prevalence 77.1%), urgency (69.9%) and lower abdominal pain (60.4%), reduced bladder capacity, and less common upper urinary tract involvement (swelling of the kidney's drainage, pooled prevalence 30.2%); improvement required stopping ketamine. [13] A 2023 review of 875 documented cases found 22% had reconstructive surgery and that progression to a severely damaged bladder may take months. [14] The esketamine label reports ulcerative or interstitial cystitis in people with long-term off-label use or misuse of ketamine, higher rates of lower urinary tract symptoms in esketamine-treated patients than placebo in clinical studies, and no cases of esketamine-related interstitial cystitis in studies up to a year, and advises monitoring for urinary symptoms. [15] See ketamine and esketamine. Label: evidence of harm for heavy non-medical use; the label governs medical use (approved medicine).

Persisting perception changes

NIDA describes hallucinogen persisting perception disorder (HPPD) as a rare condition in which people recurrently perceive images or scenes from past use. [16] A 2026 chapter says HPPD differs from brief flashbacks, appears relatively uncommon, and in most cases settles within a year, though a few cases need long-term treatment. [17] See persistent perceptual symptoms.

Gaps

Substances not covered here (for example DMT, 5-MeO-DMT, mescaline, muscimol) have their own pages, and no claim about them is made here. Where a neurological outcome is not in the sources read, it is not stated.

Next steps

Anyone with epilepsy, balance problems, kidney or bladder disease, or who takes medicines that affect seizures should talk with a clinician: talking with a health professional.