Obsessions, compulsions, or both are present.
Obsessions are recurrent and persistent thoughts, urges, or images that are experienced as intrusive and unwanted and usually cause anxiety or distress.
The person attempts to ignore, suppress, or neutralize obsessions with another thought or action.
Compulsions are repetitive behaviors or mental acts performed in response to an obsession or according to rigid rules.
The compulsions are aimed at preventing or reducing anxiety or some dreaded event or situation, but are either not realistically connected to what they are designed to prevent or are clearly excessive.

Obsessions or compulsions are time-consuming or cause clinically significant distress or impairment.

The disturbance is not better explained by another mental disorder such as GAD, body dysmorphic disorder, illness anxiety disorder, or psychosis.

OCD usually feels to patients like getting trapped in a loop. Unwanted thoughts, urges, or images show up again and again, and the person starts doing rituals or mental acts to lower the distress, even when part of them knows the cycle does not really make sense.
Core distinction: The most useful distinction is simple: obsessions are the intrusive experiences, and compulsions are what the person does to feel safer, more certain, or less distressed.
Time and impairment: In practice, OCD starts to stand out when it is eating up time, driving avoidance, or making ordinary routines feel much harder than they should.
Treatment pairing: The usual treatment conversation pairs ERP with medication. Most medication pathways start with an SSRI, with clomipramine as another classic option.
Clinical focus: Most common clinician-rated severity scale for OCD.

Most common clinician-rated severity scale for OCD.

Brief self-report symptom tracking across obsession and compulsion domains.

Quick global severity measure for routine follow-up.

Dimension-based self-report measure across contamination, responsibility, taboo thoughts, and symmetry.

These are the most established FDA-labeled medications for OCD, with age-specific approvals differing by product.

Simple Psych

Obsessive-Compulsive Disorder