Scope & substances

Includes classic serotonergic psychedelics (LSD, psilocybin), dissociatives (ketamine, PCP), empathogens (MDMA), and novel psychoactive substances. Problematic use may include frequent recreational use, risky contexts, psychosocial harm, or persistent perceptual/psychological symptoms.

Diagnostic markers & presentation

• Impaired control: repeated use despite problems, inability to reduce use, time spent obtaining/using the substance.
• Functional impairment: occupational, social or legal consequences from use or intoxication episodes.
• Persistent symptoms: ongoing perceptual disturbances (HPPD), anxiety, depressive episodes, or substance‑induced psychosis after repeated exposures.

Assessment approach

1. Detailed substance history: agent(s), dose, frequency, setting (therapeutic, ceremonial, recreational), route, and prior adverse experiences.
2. Screen for mental health disorders, suicidality, and harm (risky sexual behaviour, driving, violence).
3. Collateral history where possible and cognitive/perceptual assessment (e.g., visual symptoms in HPPD).
4. Investigations: consider toxicology, and baseline labs if medical complications suspected; neuroimaging when focal neurological signs or prolonged psychosis present.

Treatment principles

• Most care is psychosocial — motivational interviewing, CBT, relapse prevention and addressing co‑occurring psychiatric disorders.
• Brief harm reduction: advise avoidance of high‑risk settings, mixing with other substances (especially stimulants or alcohol) and educate about dose variability and adulterants.
• Specialist input for HPPD, persistent psychosis, or treatment‑resistant mood/anxiety disorders.
• Avoid routine re‑exposure to psychedelics; where therapeutic psychedelic use is legal/research‑based, ensure screening and supervised settings only.

Managing specific problems

Hallucinogen Persisting Perception Disorder (HPPD)

• Offer reassurance and psychoeducation; encourage avoidance of re‑exposure and triggers (bright lights, sleep deprivation).
• First‑line: CBT to address distress and functional impact. Pharmacological options have limited evidence — clonazepam shows occasional benefit; consider specialist psychiatry input before prescribing.

Substance‑induced psychosis or prolonged psychosis

• Manage medically with low‑dose antipsychotics if psychosis persists beyond expected intoxication period; benzodiazepines for acute agitation.
• Reassess for primary psychotic disorder if symptoms continue after abstinence and follow‑up.

Frequent recreational use / dependence‑like patterns

• Use motivational interviewing and CBT; consider community‑based psychosocial programmes, peer support and relapse prevention planning.
• Address underlying reasons for use (self‑medication for PTSD, depression or social factors) with integrated care.

Pharmacologic adjuncts — limited evidence

• Clonazepam: may reduce visual disturbances in HPPD for some patients — use cautiously due to dependence risk.
• Lamotrigine, SSRIs, or antipsychotics: occasionally tried for HPPD or persistent mood/psychotic symptoms but evidence is mixed; consult psychiatry.
• Ketamine misuse: consider naloxone not relevant; focus on psychosocial interventions and arrange medical review for urinary/urogenital problems associated with chronic ketamine use.

Risk reduction & safety planning

• Encourage safer use if cessation not immediately possible: test doses, trusted sitter, calm setting, avoid mixing substances, and readiness plans for medical help.
• Provide crisis contacts and plan for worsening mental health or psychosis; assess and document suicidal ideation risk.
• For festival or party settings, educate about adulterants and provide information on local harm reduction services where available.

Key takeaways

• Hallucinogen‑related problems are primarily managed with psychosocial interventions, harm reduction and treating comorbid conditions.
• HPPD and persistent psychosis require specialist involvement; pharmacological options are limited and should be used cautiously.
• Use episodes as opportunities for engagement, screening for mental illness and offering support/referral rather than moralising or abrupt discharge.