Category · F20-F29 block
F29 — Unspecified nonorganic psychosis
Terminology note: F29 is a true "not enough information to say more" category. It should be used sparingly and honestly — as a placeholder while more information is gathered, not as a way to avoid the work of checking the other categories.
What is this category?
F29 is used when a presentation is confidently psychotic and confidently nonorganic (not explained by a diagnosed medical condition or substance use), but there is not enough information available to specify which category — or even which atypical picture — best describes it. It is the narrowest and least informative category in the block, and is intended as a temporary or last-resort label rather than a comfortable default.
Core diagnostic concept
The classification question F29 answers is: "is this confidently a nonorganic psychosis, with genuinely insufficient information to say anything more specific, even at the level of an atypical picture?" F29 is not a shortcut for a case that simply feels complicated — it is reserved for a genuine information gap that specificity cannot yet fill.
Key diagnostic features
- Confirmed nonorganic origin
- Organic conditions and substance use have been considered and reasonably excluded, or there is strong reason to believe the presentation is not primarily due to either.
- Confirmed presence of psychosis
- Delusions, hallucinations, or comparably severe disturbance are clearly present; the uncertainty is about which specific category applies, not about whether psychosis is present at all.
- Genuinely insufficient specifying information
- Details needed to distinguish between F20-F25, or even to describe a specific F28-type atypical picture, are not yet available — for example, in an emergency setting with a very brief history and no collateral information.
- Intended as provisional
- F29 is typically expected to be revised once more information becomes available, rather than serving as a permanent classification.
How to weigh evidence
These learning labels are teaching aids, not official ICD-10 terminology (see Sources and Method).
- supports A person found in an acutely psychotic state with no available history, no collateral informant, and no opportunity yet for extended observation.
- consistent not decisive The setting is an emergency department or a brief initial contact.
- raises alternative A collateral history or a short period of further observation becomes available, allowing a more specific category to be applied.
- contradicts or weakens Enough detail is actually available to describe a specific picture or apply one of F20-F25 or F28, making 'unspecified' an under-use of the information at hand.
- missing and necessary to ask Whether any collateral history, prior records, or further observation time could realistically be obtained before defaulting to 'unspecified.'
Diagnostic boundary
F29 is distinguished from F28 by the amount of information available, not by the picture itself: F28 requires enough detail to describe a specific atypical picture that doesn't fit F20-F25; F29 is used when even that level of description is not yet possible. F29 is distinguished from F20-F25 simply by the absence of the specific information each of those categories requires — it is not a 'safer' or 'milder' alternative to them, only a less specific one.
Full comparisons:
Duration and course
Minimum duration: No duration threshold applies; F29 can, in principle, be used at first contact when information is minimal.
Course: F29 is not meant to describe a typical course, since by definition too little is known to characterise one; it is expected to be revised as more information becomes available.
Included presentations
- An acutely psychotic presentation, confidently nonorganic, encountered with too little history or observation time to apply any more specific category.
Exclusions and distinguishing presentations
| If this is true instead… | Consider | Why |
|---|---|---|
| Enough information is actually available to apply F20, F21, F22, F23, F24, or F25 with reasonable confidence | F20 | F29 should not be used when a more specific category is genuinely supported by the available information — check each category before defaulting to 'unspecified.' |
| Enough information is available to describe a specific atypical picture that clearly doesn't fit F20-F25 | F28 | F28 is the better fit once a specific description, even an atypical one, becomes possible. |
| An organic condition or substance use has not been adequately investigated or excluded | external capsule | F29 still requires a reasonable basis for believing the presentation is nonorganic, not merely an absence of investigation. |
External causes to check first
Categories in this block require that the disturbance is not better explained by another external cause listed below. These short capsules are reminders, not full teaching modules.
External cause capsule — Organic or medical causes
A reminder that F20-F29 categories require ruling out an organic brain condition before applying a primary psychiatric classification; this is not a full teaching module on organic mental disorders (see the F00-F09 block, planned).
What to check:
- Onset in the context of a known neurological condition (e.g. epilepsy, stroke, brain tumour, autoimmune encephalitis) or a general medical illness affecting the brain.
- New focal neurological signs, seizures, marked confusion, or fluctuating consciousness accompanying the psychotic features.
- Age of onset outside the usual range for a first psychotic episode, especially later-life onset without a prior psychiatric history.
- Rapid cognitive decline alongside psychotic symptoms.
A full organic-mental-disorder teaching module (F00-F09), which is outside this pilot's scope.
External cause capsule — Substance- or medication-related presentations
A reminder that psychotic symptoms temporally linked to substance use, intoxication, withdrawal, or medication require consideration of a substance-induced explanation before an F20-F29 category is applied.
What to check:
- Timing: did the psychotic symptoms begin during or shortly after intoxication or withdrawal from a psychoactive substance?
- Type of substance: stimulants, cannabis, hallucinogens, alcohol withdrawal, and some prescribed medications (e.g. corticosteroids, certain dopaminergic agents) are recognised in general clinical teaching as capable of producing psychotic symptoms.
- Course after the substance is stopped: substance-induced psychosis typically improves within days to a few weeks of abstinence, though this is not absolute.
- Whether psychotic symptoms were present before any substance use began, which would argue against a purely substance-induced explanation.
A full teaching module on F10-F19 (substance-related disorders), which is on this product's expansion roadmap.
Common learner errors
Worked example — first contact, minimal information
An unidentified man, appearing to be in his 30s, is brought to an emergency department by police after being found acutely agitated and responding to unseen stimuli in a public place. He cannot give a coherent history, no identification or collateral contact is available, and there has been no opportunity yet for extended observation or a medical work-up. Staff note he appears psychotic but cannot yet say more.
- Step 1 — Confirm psychosis is present: agitation and responding to unseen stimuli support this.
- Step 2 — Check whether an organic or substance cause can be assessed: not yet — no work-up has been possible.
- Step 3 — Check whether any F20-F25 category, or even an F28-type atypical description, can be supported: no history, no collateral information, and no observation time are available to do so.
- Step 4 — Recognise this as a genuine information gap, not a complicated but describable picture.
- Conclusion — F29 is the best provisional answer: confidently psychotic, presumed nonorganic pending work-up, with insufficient information to specify further at this first contact.
Interactive practice
- Type A An unidentified man, no history, first contact Recognition / application · Foundation
- Type B Actually, there's enough to say more Boundary / differential · Boundary
- Type C A secondhand report, nothing more Insufficient information · Developing
Retrieval prompts
Try answering each of these from memory before revealing where to check. Nothing you think or type here is sent or saved anywhere.
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What is the key difference between F29 and F28?
Reveal answer location
Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.
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Why is F29 considered a provisional label rather than a stable long-term classification?
Reveal answer location
Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.
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Name one piece of information that, if it became available, might move a case from F29 to a more specific category.
Reveal answer location
Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.
These self-checks are a personal study aid only, visible to you on this page for this visit — they are not stored and do not affect your mastery dimensions.
Rapid revision card
F29: A confidently nonorganic psychosis with genuinely insufficient information available to specify a category, even an atypical one.
Decisive boundary cues:
- Minimal history, no collateral information, no observation time yet -> weighs toward F29.
- Enough detail to describe a specific atypical picture -> weighs toward F28 over F29.
- Enough detail to apply F20-F25 with reasonable confidence -> use that category instead of F29.
Duration/course: No threshold; often a first-contact label, expected to be revised as more information becomes available.
Nearest alternatives: F28
Common mistake: Using F29 as a comfortable default for a complicated case, rather than reserving it for a genuine, checked absence of specifying information.
Retrieval prompt: Is there truly not enough information here, or have I simply not checked the other categories yet?
(or use your browser's print function) Open full-page printable revision view →
Related glossary terms
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Psychosis
A general descriptive term for a mental state in which a person's grasp of reality is significantly disturbed — typically through delusions, hallucinations, or marked thought disorder. Psychosis is a feature that can occur across many different categories, not a diagnosis in itself.
Source basis
WHO ICD-10 international classification structure and code/title (ICD-10 Browser, 2019 English release).
Original educational synthesis, informed by general published clinical-education understanding of ICD-10 F29 concepts; no verbatim CDDG or DCR text is reproduced.
Last reviewed: 2026-09-12. Full policy: Sources and Method.
Educational resource only. This page and its cases teach ICD-10 classification reasoning using fictional scenarios. It does not diagnose real people and should not be used to assess yourself or anyone else.