F43 — Reaction to severe stress, and adjustment disorders

Concept, in one sentence

F43 requires a reaction to an identifiable stressor; severity of the stressor, the specific symptom cluster, and timescale together decide which subtype applies.

Decisive boundary cues

• Hours-to-days, following an exceptionally severe stressor -> acute stress reaction.
• Weeks or longer, with re-experiencing + avoidance + hyperarousal, following a catastrophic event -> PTSD.
• A milder, more varied reaction within about a month of a significant but non-catastrophic life change -> adjustment disorder.

Duration/course cue

Acute stress reaction: hours-days. PTSD: weeks or longer. Adjustment disorder: within about a month of onset, usually resolving within six months.

Nearest alternatives

f41, f44

Common mistake

Assuming any distressing life event automatically supports PTSD, without checking the stressor's severity and the specific re-experiencing/avoidance/hyperarousal symptom cluster.

Retrieval prompt — one-line memory anchor

How severe was the stressor, what is the specific symptom cluster present, and how much time has elapsed since the event?