OCD (Obsessive Compulsive Disorder) | Symptoms, Causes and Treatment
Obsessive Compulsive Disorder is a mental health condition involving unwanted intrusive thoughts, called obsessions, and repetitive behaviours or mental acts performed to relieve the distress they cause, called compulsions. It is not about being tidy or particular. It is treatable, and the treatment with the strongest evidence is a specific form of CBT.
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What is OCD?
OCD works as a cycle, and understanding the cycle is what makes the rest of it make sense.
An unwanted, intrusive and distressing thought, image or urge enters your mind. That obsession causes intense anxiety, disgust or unease. To relieve that feeling you carry out a compulsion, a repetitive behaviour or mental act. The relief is real, and it is temporary. The obsession and the anxiety return, and the cycle begins again.
Each time you complete the compulsion, two things happen. You feel better, briefly. And you strengthen the connection between the thought and the danger it seems to signal, because you never get to find out what would have happened if you had done nothing. That is why OCD tends to grow rather than settle, and why it is unlikely to improve without proper treatment.
The other thing worth saying early is that intrusive thoughts themselves are normal. Almost everyone has unpleasant or unwanted thoughts at some point, including sudden violent or offensive mental images. What distinguishes OCD is not having the thought. It is what the thought comes to mean, and what you feel compelled to do about it.
Signs and symptoms of OCD
OCD affects around 1% of the UK population. Symptoms can begin as early as age 6, though they most often start around puberty and in early adulthood. Most people with OCD experience both obsessions and compulsions, though one may be much less obvious than the other.
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Unwanted thoughts, images, urges, doubts or worries that repeatedly enter your mind and are difficult to stop. They are typically unpleasant, and often make people feel frightened, ashamed, disgusted or embarrassed.
Common examples include fears of contamination, fears that harm will come to you or someone you love, doubts about whether you have done something, a need for things to feel right or symmetrical, and unwanted thoughts that conflict with your values.
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Physical or mental actions you feel driven to perform to reduce the distress. Physical compulsions include washing, cleaning, checking, repeating actions, touching or tapping, and arranging things in a particular order. Mental compulsions include counting, repeating words or phrases silently, praying, and reviewing memories to check what happened.
Two forms of compulsion are especially easy to miss. Seeking reassurance from family, friends, doctors or online searches functions exactly like checking. And avoidance, staying away from anything that might trigger the thought, is a compulsion in its own right.
Not all compulsive behaviours are obvious to other people, and many people with OCD hide them for years.
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OCD in children can look different, and it is often mistaken for stubbornness, anxiety or attention-seeking. Obsessions may centre on germs and cleanliness, on harm coming to a parent, on catching an illness, or on having hurt someone.
Compulsions in children often include lining objects up, repeated checking, excessive washing, counting while completing tasks, touching or tapping, and asking the same question repeatedly. At school it may appear as rewriting work until it feels right, rereading the same passage, or needing belongings arranged in a specific way.
Younger children in particular may not be able to explain what they are afraid of, and may simply become distressed when a routine is interrupted. Outcomes are better the sooner treatment begins, so it is worth acting on a suspicion rather than waiting.
Common OCD themes
You may have seen references to "the four types of OCD" online. OCD is not formally divided into four types, and no clinical classification works that way. What does exist is a set of recurring themes, and most people's OCD involves more than one, with themes that shift over time.
Contamination, involving fears about germs, illness, dirt or chemicals, usually with washing or cleaning compulsions
Checking, involving doubts about harm, safety, locks, appliances or mistakes at work
Symmetry and order, involving a need for things to be arranged or to feel right, often described as "just so"
Unacceptable or taboo thoughts, involving intrusive thoughts of a violent, sexual or blasphemous nature that are deeply distressing precisely because they conflict with the person's values
Rumination, involving prolonged mental review of a question that cannot be resolved
The theme matters much less than it appears to. Treatment addresses the cycle, and the cycle is the same regardless of what the thoughts are about.
It is not clear what causes OCD, and several factors appear to contribute. These include genetics and family history, differences in how certain brain circuits function, and stressful or traumatic life events. You are more likely to develop OCD if a family member has it.
None of these mean OCD is fixed or untreatable. Causes and maintaining factors are different things, and treatment works on the maintaining factors.
Contact our team via email to book, or learn more about our comprehensive assessments for a range of mental health conditions.
What causes OCD?
What makes OCD worse?
Several things reliably intensify OCD, and knowing them is useful.
Stress, tiredness and illness all tend to increase symptoms. So do major life changes, particularly those involving increased responsibility, such as a new job, a house move, or the birth of a child.
The two biggest factors, though, are the ones that feel most helpful in the moment. Carrying out compulsions strengthens OCD every time, even though it relieves anxiety immediately. And reassurance, whether from a partner, a parent, a doctor or an internet search, works the same way. Families who provide constant reassurance out of love are usually, without knowing it, helping the OCD rather than the person.
How is OCD diagnosed?
OCD is diagnosed by a suitably qualified professional, such as a Clinical Psychologist or psychiatrist, following a full assessment.
Assessment looks at what the obsessions are, what compulsions you carry out, how much time they take, how much distress they cause, and how far they interfere with everyday life. Diagnostic thresholds turn on distress and interference rather than on the content of the thoughts.
Assessment also checks for conditions that commonly sit alongside OCD, including depression, other anxiety disorders, body dysmorphic disorder and autism.
Treatment for OCD
Treatment in the UK follows NICE guideline CG31, Obsessive-compulsive disorder and body dysmorphic disorder: treatment.
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ERP is the core of psychological treatment for OCD. It involves deliberately facing the situations and thoughts that trigger obsessions, while not carrying out the compulsion that would normally follow.
The NHS describes it as facing your fears and having obsessive thoughts without putting them right through compulsions, starting with the situations that cause the least anxiety before moving on to more difficult ones.
It sounds daunting and it is demanding work, but the pacing matters more than the intensity. Nothing is sprung on you, steps are agreed together, and each one is chosen to be difficult but manageable. What people usually discover is that anxiety falls on its own without the compulsion, and that the feared outcome does not arrive.
Read more about exposure and response prevention.
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NICE defines the intensity of psychological treatment by therapist hours per patient, with low intensity meaning up to 10 therapist hours.
Where functional impairment is mild, or where you prefer a lower-intensity approach, NICE recommends starting with low-intensity treatment including ERP, such as brief individual CBT using structured self-help materials.
Where impairment is mild but low-intensity treatment has not worked or is not possible, or where impairment is moderate, NICE recommends a choice between a course of an SSRI and more intensive CBT including ERP of more than 10 therapist hours, because these are comparably effective.
Where impairment is severe, NICE recommends combined treatment with an SSRI and CBT including ERP.
The NHS notes that relatively mild OCD usually requires around 8 to 20 sessions of therapist treatment, with exercises completed at home between sessions, and that it can take several months before you notice the benefit.
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The medicines mainly used for OCD are SSRIs, prescribed by a GP or psychiatrist rather than a psychologist. NICE presents an SSRI and more intensive CBT as comparably effective options for moderate impairment, so this is a genuine choice rather than a fallback.
For children and young people, NICE recommends psychological treatment first, with medication considered only after an inadequate response to CBT including ERP involving the family, and following multidisciplinary review.
How to stop OCD thoughts
People often search for how to stop OCD thoughts naturally, and the honest answer is that stopping the thoughts is not the goal and not achievable.
Trying to suppress a thought makes it more frequent, not less. Worse, from an OCD perspective, the effort to push a thought away is itself a mental compulsion, so it feeds the cycle it is trying to escape.
What treatment does instead is change what the thought means and what you do next.
Support for OCD at Regal Private Therapy Practice
Our Clinical Psychologists provide CBT with exposure and response prevention for OCD, in line with NICE guidance, for adults, children and young people. Sessions are available in person in London and online across the UK.
The work is collaborative and paced. It starts with mapping your particular cycle, including the compulsions that are easy to miss, and moves at a rate you agree together. Nobody is pushed into an exposure they have not chosen.
We also recognise that OCD frequently sits alongside other things. Where autism or ADHD may be part of the picture, Regal offers ADHD and Autism assessments, and neurodiversity-affirming support. Treatment can be adapted accordingly rather than delivered as a standard protocol.
Read more about therapy for adults and therapy for children and adolescents.
If you need urgent support
If you are struggling to cope or worried about your safety, help is available now. Call 111 and select the mental health option, or contact your GP. Samaritans are available 24 hours a day on 116 123. In an emergency, call 999 or go to your nearest A&E.
Frequently asked questions about OCD
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It can be. Under the Equality Act 2010, a mental health condition is considered a disability if it has a long-term effect on your normal day-to-day activities, which includes things like concentrating, working set hours and interacting with people. Long-term means it has lasted, or is likely to last, 12 months. What matters is the effect on you rather than the diagnosis itself.
This is general information, not legal advice. If you are considering workplace adjustments, Acas and Citizens Advice both publish free guidance.
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Clinically, OCD is classified as a mental health condition rather than a neurodevelopmental condition. Autism and ADHD are neurodevelopmental; OCD sits in a different category, and in ICD-11 it heads its own group of obsessive-compulsive and related disorders.
"Neurodivergent" is not a clinical term, though. It is a self-identification used more broadly, and many people include OCD within it. Both things can be true: the clinical classification is clear, and how someone chooses to describe their own experience is theirs.
What matters practically is that OCD and neurodevelopmental conditions frequently occur together, and that assessment should look at both rather than assuming one explains everything.
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OCD can improve very substantially with treatment, to the point where it no longer meaningfully affects daily life. Clinicians tend to avoid the word cured, because intrusive thoughts occur in everyone and the aim is not to eliminate them. A realistic goal is that thoughts arrive, carry no particular weight, and require nothing of you.
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It used to be classified as one. Current classification systems place OCD in its own category of obsessive-compulsive and related disorders, alongside conditions such as body dysmorphic disorder and hoarding disorder. Anxiety is still central to how OCD works, which is why treatment shares a great deal with anxiety treatment.
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The most useful thing is often counter-intuitive: stop providing reassurance, and stop participating in compulsions. Both relieve distress in the moment and strengthen OCD over time. Agree the change together rather than withdrawing suddenly, ideally with the person's therapist involved. Beyond that, take it seriously, do not treat it as a personality quirk, and encourage treatment.
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Some people describe having obsessions without visible compulsions, often called Pure O. In practice, compulsions are usually present but mental rather than physical: reviewing, mentally checking, silently reassuring yourself, or repeatedly testing how a thought makes you feel. This matters clinically, because those mental compulsions maintain the cycle in exactly the same way visible ones do, and treatment works on them the same way.
Intrusive thoughts themselves are extremely common and are not a sign that you want to act on them. In OCD, the distress arises because the thought is so contrary to who you are. That distinction is one of the things a proper assessment establishes.
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References
NICE (2005, last reissued 2024). Obsessive-compulsive disorder and body dysmorphic disorder: treatment. Clinical guideline CG31. https://www.nice.org.uk/guidance/cg31
NHS. Obsessive compulsive disorder (OCD): overview, symptoms and treatment. https://www.nhs.uk/mental-health/conditions/obsessive-compulsive-disorder-ocd/
Mersey Care NHS Foundation Trust. Children and young people's guide to OCD.
South London and Maudsley NHS Foundation Trust. Information about OCD for children, young people and families.