What is OCD?
OCD has two parts. Obsessions are recurrent, intrusive thoughts, images or urges that feel unwanted, senseless or disturbing and provoke anxiety, doubt or disgust. Compulsions are repetitive behaviours (washing, checking, arranging) or mental acts (praying, counting, reviewing, seeking reassurance) that the person feels driven to carry out in response to an obsession or according to rigid rules. The cycle is self-reinforcing: compulsions bring brief relief, which teaches the brain that they are necessary, so obsessions return stronger.
To meet criteria, symptoms take more than an hour a day or cause significant distress or impairment. Insight varies: many people know their fears are exaggerated yet feel unable to resist.
Common obsessions
- Fear of contamination by germs, dirt, bodily fluids or chemicals.
- Fear of causing harm, by mistake or negligence (leaving a door unlocked or the stove on).
- Fear of harming oneself or others, in violent images or urges that are unwanted.
- Need for symmetry, order or things feeling “just right”.
- Unwanted sexual, religious or blasphemous thoughts and images.
- Doubts about relationships, sexual orientation or moral character.
- Fear of losing or throwing away important items.
Common compulsions
- Excessive washing, cleaning or avoiding “contaminated” objects.
- Repeated checking of locks, appliances, emails or the body.
- Arranging, ordering or repeating actions until they feel right.
- Counting, tapping or touching in a set pattern.
- Mental rituals: praying, neutralising “bad” thoughts, mentally reviewing events.
- Seeking reassurance repeatedly from others or the internet.
- Hoarding and difficulty discarding items.
- Avoidance of situations, places or people that trigger obsessions.
Main OCD themes (“types”)
OCD is a single disorder with many themes. Clinicians often describe dimensions that help tailor treatment:
- Contamination and cleaning (washing OCD).
- Checking and doubt (harm prevention).
- Symmetry, ordering and “just right” OCD.
- Harm and intrusive thoughts (aggressive or violent obsessions).
- Sexual and religious (scrupulosity) obsessions.
- Relationship and “real event” OCD (doubt and rumination).
- Hoarding (now a separate diagnosis in many classifications).
- “Pure O” (mainly mental compulsions; rituals are covert, not absent).
Themes can change over time, but the underlying cycle of obsession and compulsion stays the same.
Causes and risk factors
- Genetic factors: OCD runs in families.
- Brain circuits and chemistry (serotonin and others) involved in habit, threat detection and decision-making.
- Temperament, perfectionism and an inflated sense of responsibility.
- Stressful or traumatic life events, and major life changes such as pregnancy or childbirth.
- In some children, sudden-onset OCD after an infection (PANS/PANDAS) is described; this requires specialist evaluation.
- OCD is not caused by poor parenting or personal weakness.
How OCD is diagnosed
A mental health professional interviews you about thoughts, rituals, time spent, distress and impairment, and screens for coexisting problems such as depression, anxiety, tics, ADHD, autism, eating disorders and substance use. Tools such as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) measure severity. Medical causes and substances that can mimic OCD symptoms are considered. Many people wait years for a correct diagnosis, partly because of shame or because themes are not recognised as OCD.
Treatment: CBT with exposure and response prevention
ERP is the first-line psychological treatment, recommended by NICE and international guidelines. Together with a therapist, you build a ladder of feared situations, from mildly to highly distressing, and practise facing them without carrying out the compulsion, letting the anxiety rise and fall naturally. Over time the brain learns that the feared outcome does not occur or can be tolerated, and obsessions lose their grip. A course usually takes 12–20 sessions with daily practice, and about 60–70% of people improve substantially. For mental compulsions and intrusive thoughts, ERP also targets the rituals of reassurance, reviewing and neutralising. Online and group formats also work.
Medication
- SSRIs (fluoxetine, sertraline, fluvoxamine, paroxetine, escitalopram) are first-line medicines; OCD often needs higher doses than depression and 8–12 weeks to show full effect.
- Clomipramine, a tricyclic, is an alternative.
- Augmentation with low-dose antipsychotic medication for some people who respond partially.
- Combination with ERP is recommended for moderate to severe OCD.
- Treatments such as deep brain stimulation and TMS are reserved for severe, treatment-resistant cases at specialist centres.
Self-help and daily strategies
- Learn about OCD and label it: “This is an obsession, not a real danger.”
- Gradually reduce compulsions and reassurance seeking, delaying them for a few minutes and extending the delay.
- Resist avoiding triggers; plan gradual exposure.
- Keep a regular routine for sleep, exercise and meals, which help overall anxiety.
- Avoid alcohol and drugs as ways to cope.
- Join a support group or reach out to a therapist.
- See also pensamientos intrusivos (Spanish) and how to stop overthinking.
OCD in children and teenagers
Children may carry out rituals secretly, ask for repeated reassurance, avoid specific places or become very distressed when routines are interrupted. Family accommodation (joining in rituals, answering repeated questions) inadvertently maintains symptoms; therapists work with parents to reduce it supportively. CBT with ERP, adapted to age, is the first-line treatment, with SSRIs added for moderate to severe cases.
When to seek help
- Obsessions or rituals taking more than an hour a day.
- Distress or impairment at work, school or relationships.
- Avoiding places, people or activities because of fears.
- Skin damage from washing or loss of sleep.
- Depression, panic or thoughts of self-harm.
- A child with sudden onset of severe OCD symptoms.
Three common situations
Spending two hours a day washing hands and avoiding doorknobs: contamination OCD; ERP is highly effective.
Returning home three times to check the stove: checking compulsions; practise leaving without re-checking and tolerate the doubt.
Horrified by sudden images of harm to a loved one: classic intrusive thoughts in OCD; seek a therapist experienced in ERP.
Key points to remember
OCD is a treatable condition characterised by distressing obsessions and compulsive rituals. ERP and SSRIs help most people. Seek early assessment and avoid compulsions and reassurance seeking. Our psychology team offers evidence-based support.
This guide is for general information and does not replace an assessment by a qualified health professional.
Questions about OCD
These answers are general information and do not replace an examination or individual medical advice.
What is the difference between OCD and being a perfectionist?
OCD involves unwanted intrusive thoughts and rituals that cause distress and take time; perfectionism is a trait without these features.
What is the best treatment for OCD?
CBT with exposure and response prevention, with or without an SSRI.
Can OCD go away by itself?
It usually persists and fluctuates without treatment, but therapy can lead to major improvement.
Do intrusive thoughts mean I will act on them?
No. In OCD they are unwanted and distressing, and people are very unlikely to act on them.
How long does ERP take?
Typically 12–20 sessions with daily practice.
Can children have OCD?
Yes, often from childhood or adolescence, and it responds well to treatment.
Sources
- NICE · Obsessive-compulsive disorder and body dysmorphic disorder: treatment (CG31)
- NHS · Obsessive compulsive disorder (OCD)
- NIMH · Obsessive-compulsive disorder
- International OCD Foundation · About OCD
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.