Category: F20 F21 F22 F23 F24 F25 F28 F29
F23 — Acute and transient psychotic disorders: facilitator sheet
Teaching objective
The classification question F23 answers is: "has a psychotic picture developed acutely (within about two weeks) and is it expected to, or has it already begun to, resolve within a short window, rather than persisting as a sustained illness?" F23 asks about timeline and trajectory; it deliberately does not ask learners to wait indefinitely, but it does require enough timeline information to distinguish an acute, likely self-limiting episode from an evolving F20 presentation.
Choose material
Worked example · Case: Three days, a lost job, and a shifting picture · Case: Acute, dramatic — and a substance history · Case: Three days in, severe but new · Case: Past the expected window · Case: A frightening first episode · Case: Sorting the evidence — fast onset, shifting picture
Worked example
Show scenario
Youssef, 34, was well until three days ago, shortly after unexpectedly losing his job. Since then he has expressed a rapidly changing set of beliefs — first that coworkers conspired against him, then, within the same day, that he has a special mission to warn the public about a disaster — alongside brief episodes of hearing voices that come and go. His mood swings between intense fear and elation within hours. He is bewildered and disoriented about what is happening to him. There is no history of similar episodes, no substance use, and no medical illness.
Reveal step 1
Step 1 — Check onset speed: the picture developed over three days, following a clear acute stressor — well within F23's acute-onset window.
Reveal step 2
Step 2 — Check symptom stability: the delusional content and mood are both shifting rapidly from hour to hour and day to day, a polymorphic pattern characteristic of F23 rather than F20's more stable picture.
Reveal step 3
Step 3 — Check duration so far: only three days have elapsed, far short of F20's one-month threshold.
Reveal step 4
Step 4 — Check for external causes: no substance use or medical illness is reported, and no mood episode independent of the psychotic features is described.
Reveal step 5
Conclusion — F23 is best supported at this stage: acute onset, rapidly shifting polymorphic picture, following a clear stressor, with the classification to be reassessed if the episode continues beyond the expected window.
Comparison points
F23 is distinguished from F20 mainly by onset speed and expected course: F23 develops acutely (about two weeks or less) and is expected to resolve within a short window, while F20 requires characteristic symptoms present for most of the time over at least one month, often continuing well beyond. If an F23-type presentation persists beyond its expected window, the classification should be revisited and may shift toward F20. F23 is distinguished from F22 by both onset and breadth: F22 is a slow-building, narrow, persistent delusional system, while F23 is a fast-onset, often broader and more rapidly shifting picture. F23 is distinguished from a mood disorder with psychotic features (outside this block) by checking whether the psychotic symptoms are confined to, and explained by, a manic or depressive episode.
Misconception prompt
Ignoring duration and course: "This looks severe, so it must be the most serious category — schizophrenia."
Ask the class why this reasoning fails before revealing the explanation below.
Reveal why it fails
Severity at a single point in time does not tell you duration or course, and duration/course is exactly what separates F20 from F23 (and shapes the F20/F25 boundary too). A dramatic acute presentation is at least as consistent with F23 as with F20, and sometimes more so.
Discussion prompts
Prompt 1
What two timeline features most strongly support F23 over F20?
Prompt 2
Why might a case need to be classified provisionally, with a note to reassess later, rather than definitively at first presentation?
Prompt 3
Explain why symptom severity alone cannot distinguish F23 from F20.
Summary
A psychotic episode with acute onset (about two weeks or less) and an expected brief course, often following a stressor, regardless of how severe or F20-like the symptoms look during the episode.