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obsessive compulsive disorder (OCD)

Obsessive Compulsive Disorder (OCD)

Obsessions are thoughts, images, and impulses that pop – unwanted – into your mind and which cause you distress. Compulsions are the actions (observable or not) that you take in response to your obsessions. You might perform a compulsion with the goal of reducing your anxiety, or with the intention of preventing a dreaded outcome. People who experience both obsessions and compulsions are said to have obsessive compulsive disorder (OCD) and it is thought that between 1 and 2 people out of every 100 experience OCD every year [1]. OCD responds well to psychological treatments including cognitive behavioral therapy (CBT) and exposure and response prevention (ERP).

What is it like to have OCD?

Monica’s fear that she would harm her baby

Shortly after the birth of her first baby, Monica started to become afraid that she would cause harm to her. She would have unwanted thoughts and images of herself smothering or suffocating her baby. If she found herself in high places, she would have unwanted images of throwing her baby. To Monica these thoughts and images were repugnant and completely unacceptable – she was a caring and conscientious parent and these images were the exact opposite of how she wanted to behave. Monica came to the conclusion that having these thoughts and images meant that she was a terrible mother and couldn’t be trusted to be alone with her baby. As much as she was able to, she tried to push these thoughts away. To keep her baby safe Monica insisted that her husband be responsible for most of the child’s care. If she could not avoid looking after her baby, then she prayed in her mind that nothing bad would happen. She didn’t tell anyone about her thoughts in case she was locked away.

Aspects of treatment that Monica found helpful

Monica was initially reluctant to see a psychologist as she thought she would have her baby taken away from her. She and her therapist discussed intrusive thoughts and together they developed alternative hypotheses about what was happening to her. One theory was that “I’m a terrible mother and I can’t be trusted to be alone with my child”. The alternative theory was “I would never harm my baby, but my anxiety problem makes me doubt this”. They looked at the evidence for these two theories, but although Monica hoped the second was true, she didn’t really believe it. Monica and her therapist drew up a list of situations that she had been avoiding and Monica practiced exposing herself to these, initially in her therapy sessions and later as homework. Tasks like feeding or bathing her baby initially caused her tremendous anxiety but with encouragement she persisted. She experimented with what happened when she allowed her intrusive thoughts to be present rather than pushing them away. One of the most helpful things that she did was to test her belief that she was a terrible mother by asking other mothers to complete an anonymous survey about the thoughts and images that they experienced. She was relieved to find that she was far from alone. By the end of therapy Monica was able to spend time alone with her baby without fear of harming her. She wrote herself a letter “Your OCD is like an over-cautious friend – it’s looking out for you but it’s trying too hard. You’re a good mother, and the OCD only developed because you care so much.”

What Is OCD?

OCD is defined by the presence of obsessions and compulsions. A diagnosis of OCD should only be made by a mental health professional but at a minimum, obsessions and compulsions must be present most days for the last 2 successive weeks and must cause significant distress or interference with other activities [2].


Obsessions are recurrent and persistent thoughts, urges, or impulses. People with OCD experience them as intrusive and unwanted – they are unacceptable or repulsive – and they tend to provoke feelings of anxiety. When someone with OCD has an obsessive thought they tend to try to suppress or neutralize it with some other thought or action. Obsessions in OCD tend to follow common themes. Some of the most common obsessive themes are:

  • Losing control: e.g. having an impulse to harm yourself, an impulse to harm someone else, or an impulse to shout something obscene.
  • Contamination: e.g. by bodily fluids, by a chemical, or by germs or disease.
  • Sexual: e.g. unwanted sexual thoughts or images, sexual obsessions about children, sexual obsessions about homosexuality.
  • Harm: e.g. worry about being responsible for something awful happening, having a fear of hurting other people by not being careful enough.
  • Religion: e.g. worry about offending God, concern about morality.
  • Perfectionism: e.g. a need to know or remember for certain, being concerned with exactness, preciseness, or orderliness.


Compulsions are actions, rituals or behaviors that are done to relieve the anxiety or distress caused by the obsessions. Compulsions can be overt / external (visible things you do in the outside world) or covert / internal (things you do in your own mind). People with OCD usually perform their compulsions to prevent the thing they are thinking about from happening, to make sure that they have at least done everything within their power to prevent it from happening, or to feel less anxious. People with OCD might realize that their actions are not rational but will feel compelled to carry them out anyway. Examples of common compulsions include:

  • Repeated checking: e.g. checking that you did not harm yourself or someone else, checking that something terrible did not happen, checking that you did not make a mistake.
  • Washing and cleaning: e.g. washing your hands excessively, cleaning your house or particular items obsessively, excessive washing or grooming.
  • Mental compulsions: e.g. praying to prevent harm, ‘cancelling’ a bad thought or word with a good one, counting and ending on a ‘right’ or ‘good’ number.
  • Repeating: e.g. repeating activities, repeating body movements, repeating a mental event.
How you might think How you might feel How you might act
  • Intrusive thoughts, images, urges, or doubts which ‘pop’ into your mind (obsessions)
  • Thoughts about the obsessions and what they mean
  • Thoughts about what having the obsessions says about you
  • Anxious
  • Afraid
  • Tense
  • Upset
  • Worried
  • Ashamed
  • Embarrassed
  • Disgusted
  • Try to push away the thoughts, images, urges, doubts, or feelings
  • Take action to make sure that your worries don’t come true
  • Act to make things safe
  • Neutralize the thoughts with actions or rituals
  • Act to reduce your feelings of responsibility
  • Seek reassurance
  • Avoid situations that trigger your fears

What causes OCD?

There is no single cause for OCD. Some of the factors that make it more likely that a person will experience OCD include:

  • Early experiences which made you vulnerable to OCD, or which made you feel particularly responsible for preventing bad things from happening. For example, having too much responsibility too early, learning about superstitions.
  • Critical incidents such as stresses or challenges which kick-start the OCD. Situations which make you feel a sense of responsibility or which give you a sense of not being in control can be particularly potent triggers [3].
  • Assumptions and beliefs can predispose you to developing OCD. Beliefs about how responsible you are, or about how important your thoughts are (particularly what having these thoughts says about you), seem to be relevant [4, 5].
  • Genetic factors play less of a role in OCD than many people assume. There may be genes which predispose people to developing emotional problems in general, but no specific genes which predispose people to developing OCD [6].

What keeps OCD going?

Cognitive behavioral therapy (CBT) is always very interested in what keeps a problem going. This is because if we can work out what is keeping a problem going, we can treat it by intervening to interrupt this maintenance cycle.

The important message from CBT is that it is not the intrusions that lead to distress but rather it is the meaning that we bring to them (the way that we interpret them) that leads to such negative consequences [7].

Once you have interpreted particular thoughts as personally significant, you are likely to take certain forms of action to keep yourself or others safe. These include:

  • Safety strategies. Avoiding certain situations which you think might be dangerous or using safety behaviors to minimize the chance of catastrophe if you do have to confront a feared situation.
  • Neutralizing actions. Taking actions to make unwanted thoughts or urges less dangerous. Taking action to make you feel less responsible if the bad thing does happen. For example, praying if you have a blasphemous thought, washing your hands if you believe that they have become contaminated and could contaminate others.
  • Changes in what you pay attention to, and the kinds of conclusions you draw. These ‘attention and reasoning biases’ might have become so habitual that they are automatic. E.g. paying close attention to certain thoughts in case they are ‘dangerous’ or could lead to an unwanted outcome.

Treatments for OCD

Psychological treatments for OCD

Effective psychological treatments for OCD include cognitive behavioral therapy (CBT) and exposure and response prevention (ERP). The UK National Institute of Health and Care Excellence guideline for OCD recommends that if a client presents with OCD where the degree of impairment is mild they should be offered a minimum of 10 therapist hours, with treatment length increasing in line with OCD severity [8].

OCD specialists have made some recommendations about the ‘ingredients’ of what high quality CBT for OCD should look like [9]. The most important ingredients of high-quality CBT for OCD include:

  • Sessions that are focused on the OCD problem for most of the time in most of the sessions.
  • Working towards collaboratively developed goals which are specific, achievable, and described in terms of what you will do.
  • An explanation of how your OCD works and what keeps it going (a case conceptualization).
  • Therapist-aided exposure where you have an opportunity to test some of your beliefs and to feel anxious.
  • Between-session tasks likely to consist of monitoring, exposure, and behavioral experiments.
  • Encouragement to do things which expose you to thoughts, activities, or situations that you are tempted to avoid.
  • Consistent encouragement to resist your rituals or compulsions.

Medical treatments for OCD

The UK National Institute for Health and Care Excellence (NICE) recommends that selective serotonin reuptake inhibitors (SSRIs) are effective in treating adults with OCD [8].

How can I overcome my OCD?

There are lots of steps that you can take for yourself that will help you to overcome obsessive compulsive disorder. Treatment approaches for OCD can broadly be divided in behavioral (typically exposure and response prevention) and cognitive-behavioral types, although they overlap to a considerable degree.

Helpful techniques no matter what approach you choose

  • Set goals for your recovery. Treatment for OCD involves confronting your fears. A helpful way of staying motivated in the face of fear is to think about how life will be better once you have tamed your OCD. Spend a little time thinking about why you want to recover and what your life would look like if your were no longer affected by OCD. Some other people’s goals for treatment have included:
    • I want to be able to hold my baby
    • I want to be able to use public toilets
    • I want to be able to open a door handle with my hand
    • I want to be on time (not controlled by my rituals)
    • I want to be able to work

    Set goals for your recovery by thinking about things that you want to be able to do. You can use the Psychology Tools Problem List worksheet as a first step in clarifying your problems and goals.

  • Learn about intrusive thoughts and thought suppression. You might not believe it at this point, but intrusive thoughts are normal, and everybody has them. As a society, though, we don’t often have many opportunities to talk about our intrusive thoughts with other people– perhaps because they are socially unacceptable and for fear of what other people might think of us. The result of this avoidance is that we don’t have many opportunities to realize that other people are having them too. The key difference in people who are bothered by their intrusive thoughts is that they interpret them as being personally significant. The Psychology Tools exercise Intrusive Thoughts, Images, and Impulses can help you to understand more about intrusive thoughts experienced by ‘normal’ people. One very common misconception is that we can control our thoughts. Put simply, we can’t. Our brains are thinking machines – they spend a lot of time planning, judging, thinking, and worrying. Some of this we do deliberately, but much of it happens automatically. Worse, when we start trying to control or suppress unwanted thoughts they are more likely to recur – a phenomenon known as the ‘rebound effect’. You can learn more about thought suppression from the Psychology Tools handout Thought Suppression and Intrusive Thoughts. If you have been trying to push away ‘unacceptable’ thoughts then now is the time to try other strategies.
  • Monitor your obsessions and compulsions. To treat a problem like OCD it is helpful to know what you are up against. You can use diaries and symptom records to learn about situations which bother you (triggers) as well as the obsessions and compulsions that you experience in these situations. The Psychology Tools OCD Diary is helpful for this purpose.

Behavioral approach

  • Expose yourself to what you fear. Exposure is the most effective psychological treatment for fears. Once you know what situations you are afraid of it is time to expose yourself to them. One way of doing this is to construct an Exposure Hierarchy and then work your way up. When you are doing exposure the aim is to feel some anxiety and to stay in the anxiety-evoking situation. You can learn about why this is helpful in our habituation handout. Traditionally the ‘rule of thumb’ for exposure has been to stay in the anxiety-provoking situation until your anxiety has reduced by at least half. You can use the Psychology Tools Exposure Record to help you to conduct exposure exercises.
  • Response prevention. Exposure for OCD incorporates an extra ‘twist’ to make it more effective – this is called response prevention. A side-effect of performing your compulsions is that you don’t get to find out if your obsessional worries are true. For example, John believed that if he didn’t wash his hands to remove contamination then his family would become ill and he would be responsible. He wasn’t able to test the truth of his belief until he got his hands dirty and resisted the urge to wash them. Resisting the urge to perform your compulsions (the ‘response prevention’ part of exposure and response prevention) is a crucial part of overcoming OCD. Use the Psychology Tools Exposure and Response Prevention worksheet to carry out ERP for OCD.

Cognitive behavioral approach

  • Consider different ways of thinking about your OCD using Theory A vs. Theory B. The cognitive model of OCD says that it is not the intrusive thoughts that are problematic in themselves (everybody has them) but rather it is the meaning we give to these thoughts. The thoughts you have about the intrusions drive your responses that are intended to keep you safe, but which actually end up keeping the OCD going. It is vitally important that you start to develop another way of viewing your OCD interpretations. A technique that psychologists often use with people who have OCD is the Theory A / Theory B tool. The starting point of this technique is “What if my interpretation of my intrusions is wrong? Could there be another way of understanding them?”.
  • Use behavioral experiments to test the accuracy of your appraisals. The CBT model of OCD says that it is what your obsessions mean to you that causes you so much distress. For example, John thought that having unwanted violent thoughts meant that he was a terrible person and likely to lose control. One task of CBT for OCD is to test whether your beliefs are true and accurate. To understand how you are making sense of your OCD you could ask yourself these questions:
    • What do you think it says about you that you have these intrusive thoughts?
    • What do you think other people would think of you if they know what went through your mind?
    • What would happen if you didn’t perform your compulsion?

    The CBT model of OCD says that it is your appraisals (your answers to the questions above) that are the reason why you find your intrusions so upsetting. The thing is, sometimes our appraisals are not true. The question that CBT poses is “How can we find out?”. Behavioral experiments in OCD are designed to help you to find out. Behavioral experiments in OCD might include:

    • Conducting surveys to find out whether other people have similar thoughts, and what they think about these thoughts.
    • Exploring the validity of some of the beliefs we have about ourselves (e.g. testing whether we are bad, responsible, or out of control).
    • Exploring the consequences of checking vs. not-checking (e.g. do you feel more certain when you check?).
    • Exploring what happens when we don’t perform our compulsions (e.g. does your anxiety go high and stay high?).

    For more information read the section about how to carry out effective behavioral experiments.

  • Learn about cognitive biases in OCD. A cognitive bias is sometimes called a ‘thinking error’ or an ‘unhelpful thinking style’. It is literally a mistake in your thinking and is normally one which is invisible to you unless you are paying close attention to it. Different cognitive biases are associated with different conditions. For example, depression is associated with a negativity bias (failure to see positive information) and panic is associated with catastrophic misinterpretation (worst outcomes are seen as probable even if they are unlikely). OCD has been associated with a number of cognitions and cognitive biases [4]:
    • Having a thought about an action is morally equivalent to performing the action (moral thought-action fusion).
    • If a thought comes to mind, this means that this thought is likely to come true (probability thought-action fusion).
    • Assuming that if a thought comes repeatedly to mind, it must have some special meaning.
    • Failing to prevent harm is the same as having caused the harm in the first place.
    • One can and should exercise control over one’s thoughts (beliefs about controllability of thoughts).
    • An exaggerated belief in one’s ability to produce or prevent negative outcomes (inflated responsibility).
    • The idea that there is a right way to do everything and that I must do it that way (perfectionism).
    • A tendency to overestimate the likelihood of danger or harm (threat overestimation).
    • The belief that it is necessary to be certain and the one must be certain in order to cope (intolerance of uncertainty).

    For other mental health problems such as depression, thought challenging exercises are recommended when cognitive bias is present. Expert advice for OCD is that this is unnecessary: for OCD behavioral approaches such as exposure and behavioral experiments are more effective ways to explore the validity of these beliefs and biases [10].


[1] Kessler, R. C., Chiu, W. T., Demler, O., & Walters, E. E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, 62(6), 617-627.

[2] American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (DSM-5®). American Psychiatric Pub.

[3] Fontenelle, L. F., Cocchi, L., Harrison, B. J., Shavitt, R. G., do Rosário, M. C., Ferrão, Y. A., … & de Jesus Mari, J. (2012). Towards a post-traumatic subtype of obsessive–compulsive disorder. Journal of Anxiety Disorders, 26(2), 377-383.

[4] Obsessive Compulsive Working Group (1997). Cognitive assessment of obsessive-compulsive disorder. Behaviour Research and Therapy, 35(7), 667–681.

[5] Cougle, J. R., Lee, H. J., & Salkovskis, P. M. (2007). Are responsibility beliefs inflated in non-checking OCD patients?. Journal of Anxiety Disorders, 21(1), 153-159.

[6] Mattheisen, M., Samuels, J. F., Wang, Y., Greenberg, B. D., Fyer, A. J., McCracken, J. T., … & Riddle, M. A. (2015). Genome-wide association study in obsessive-compulsive disorder: results from the OCGAS. Molecular Psychiatry, 20(3), 337.

[7] Salkovskis, P. M., Forrester, E., & Richards, C. (1998). Cognitive–behavioural approach to understanding obsessional thinking. The British Journal of Psychiatry, 173(S35), 53-63.

[8] National Institute for Health and Care Excellence (2005). Obsessive compulsive disorder and body dysmorphic disorder: treatment. Retrieved from:

[9] Darnley, S., Forrester, E., Heyman, I., Stobie, B., Salkovskis, P, Veale, D. (2019). CBT Checklist for OCD. Retrieved from:

[10] Salkovskis, Paul. (2019). Yes, that’s right. Often that means doing rather different stuff such as not using TRs due to potential for confusion between intrusions and appraisals. Just saying in the C bit of CBT typically don’t use TRs. Book has details! [Tweet] Retrieved from

About this article

This article was written by Dr Matthew Whalley and Dr Hardeep Kaur, both clinical psychologists. It was reviewed by Dr Hardeep Kaur and Dr Matthew Whalley on 2019-09-12. Last review 2020-08-05.