Symptoms used to diagnose
The ruleObsessions, compulsions or both that take over an hour a day or cause significant distress. Insight level is noted (good, poor, or absent).
Core symptoms
- Obsessions: unwanted intrusive thoughts, images or urges causing distress
- Compulsions: repeated behaviours or mental acts to reduce distress
Other symptoms
- Contamination fears and washing
- Doubt and checking
- Need for symmetry or 'just right'
- Taboo or harm-related intrusive thoughts
- Mental rituals (counting, praying, reviewing)
- Avoidance of triggers
How diagnosis works
- Obsessions, compulsions, or both.
- Time-consuming (often over 1 hour a day) or causing significant distress or impairment.
- Insight is rated good, poor or absent.
A diagnosis is made by a qualified clinician after a full assessment — this summary is to help you understand it, not to self-diagnose.
Commonly used medications
Therapies & support
- CBT with exposure and response prevention (ERP)
Good to know
- OCD often needs higher SSRI doses and a longer trial (up to 12 weeks).
Sources
- 01Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR)
American Psychiatric Association, 2022
- 02ICD-11 for Mortality and Morbidity Statistics — Chapter 6: Mental, behavioural or neurodevelopmental disorders
World Health Organization, 2022
- 03The Maudsley Deprescribing Guidelines
Horowitz & Taylor, Wiley-Blackwell, 2024