F16 — Mental and behavioural disorders due to use of hallucinogens

Concept, in one sentence

Perceptual alteration is hallucinogen intoxication's expected primary effect; a more sustained delusional/hallucinatory picture is a psychotic disorder, while brief spontaneous recurrences without further use are the residual/late-onset subtype ("flashbacks").

Decisive boundary cues

• Perceptual alteration confined to, and resolving with, the intoxication period -> F16.0, not a disorder.
• A sustained delusional/hallucinatory picture beyond expected intoxication -> F16.5.
• Brief, spontaneous recurrence with no further use in between -> F16.7, not ongoing intoxication.

Duration/course cue

Intoxication resolves within hours; flashback-type recurrences are brief (seconds to minutes) and can occur sporadically well after use has stopped.

Nearest alternatives

F12

Common mistake

Treating any perceptual disturbance during hallucinogen use as inherently pathological, rather than recognising it as the substance's expected primary effect.

Retrieval prompt — one-line memory anchor

What single question would you ask first about whether any further use has occurred since the first episode?