Obsessive-compulsive Disorder

Obsessive-compulsive disorder (OCD) is a common mental health problem. Symptoms typically include recurring obsessive thoughts, and repetitive compulsions in response to the obsession. A common example is recurring obsessive thoughts about germs and dirt, with a compulsion to wash your hands repeatedly to "clean off the germs". However, there are many other examples. The usual treatments are cognitive behavioural therapy, a selective serotonin reuptake inhibitor (SSRI) antidepressant medicine, or both. Treatment often works well to reduce the symptoms and distress of OCD greatly.

This leaflet is part of our series on anxiety and phobias

  • Acute Stress Disorder
  • Agoraphobia
  • Generalised Anxiety Disorder
  • Obsessive-compulsive Disorder
  • Panic Disorder
  • Post-traumatic Stress Disorder
  • Social Anxiety Disorder

What is obsessive-compulsive disorder?

Obsessive-compulsive disorder (OCD) is a condition where you have recurring obsessions, compulsions, or both.

What are obsessions?

Obsessions are unpleasant thoughts, images, or urges that keep coming into your mind. Obsessions are not simply worries about your life problems. Common obsessions include:

  • Fears about contamination with dirt, germs, viruses (eg HIV), etc.
  • Worries about doors being unlocked, fires left on, causing harm to someone, etc.
  • Intrusive thoughts or images of swearing, blasphemy, sex, someone harmed, etc.
  • Fear of making a mistake or behaving badly.
  • A need for exactness in how you order or arrange things.
  • A compulsion to collect things that others might throw away (hoarding).

These are examples. Obsessions can be about all sorts of things. Obsessive thoughts can make you feel anxious or disgusted. You normally try to ignore or suppress obsessive thoughts; for example, you may try to think other thoughts to neutralise the obsession.

What are compulsions?

Compulsions are thoughts or actions that you feel you must do or repeat. Usually the compulsive act is in response to an obsession. A compulsion is a way of trying to deal with the distress or anxiety caused by an obsession.

For example, you may wash your hands every few minutes in response to an obsessional fear about germs. Another example is you may keep on checking that doors are locked, in response to the obsession about doors being unlocked. Other compulsions include repeated cleaning, counting, touching, saying words silently, arranging and organising - but there are others.

How does obsessive-compulsive disorder affect your life?

The obsessions that you have with OCD can make you feel really anxious and distressed. The compulsions that you have may help to relieve this distress temporarily but obsessions soon return and the cycle begins again.

The severity of OCD can range from mildly inconvenient to causing severe distress. You know that the obsessions and compulsions are excessive or unreasonable. However, you find it difficult or impossible to resist them.

OCD affects people in different ways. For example, some people spend hours carrying out compulsions and, as a consequence, cannot get on with normal activities. Some people do their compulsions over and over again in secret (like rituals). Other people may seem to cope with normal activities, but are distressed by their recurring obsessive thoughts. OCD can affect your work (or school-work in children), relationships, social life, and your quality of life.

Many people with OCD do not tell their doctor or anyone else about their symptoms. They fear that other people might think they are crazy. Some people with OCD may feel ashamed of their symptoms, especially if they contain ideas of harming others, or have a sexual element. As a result, many people with OCD also become depressed. However, if you have OCD, you are not crazy or mad. It is not your fault and treatment often works. If you are concerned that you may be depressed (for example, if you have been feeling very down and you no longer take pleasure in the things that you used to enjoy), you should see your doctor.

What causes obsessive-compulsive disorder?

The cause of OCD is not clear. Slight changes in the balance of some brain chemicals (neurotransmitters) such as serotonin may play a role. This is why medication is thought to help (see below).

Also, the chance of developing OCD is higher than average in first-degree relatives of affected people (mother, father, brother, sister, child). So, there may be some genetic element to OCD. However, so far, no genes have been found to be linked with OCD.

Other theories about the cause of OCD have been suggested, but none proved.

Who gets obsessive-compulsive disorder?

It is thought that between 1 to 3 in 100 adults have OCD. Anyone at any age can develop OCD but it usually first develops between the ages of 18 and 30. About 2 in 100 children are also thought to have OCD. Statistics suggest that women are more affected than men.

OCD is usually a chronic (persistent) condition.

How is obsessive-compulsive disorder diagnosed?

If you are concerned that you may have OCD, you should see your doctor and explain your concerns. They may start by asking some of the following questions. These questions can act as a screen for possible OCD:

  • Do you wash or clean a lot?
  • Do you check things a lot?
  • Is there any thought that keeps bothering you that you would like to get rid of, but cannot?
  • Do your daily activities take a long time to finish?
  • Are you concerned about putting things in a special order, or are you upset by mess?
  • Do these problems trouble you?

A more detailed assessment is then needed for OCD to be diagnosed. This may either be carried out by your doctor or by a specialist mental health team. The assessment will look at any obsessional thoughts and compulsions that you have and how they affect you and your daily life. Children with OCD may be referred to a specialist mental health team which is experienced in assessing and treating children with OCD.

What is the treatment for obsessive-compulsive disorder?

The usual treatment for OCD is:

  • Cognitive behavioural therapy (CBT); or
  • Medication, usually with an SSRI antidepressant medicine; or
  • A combination of CBT plus an SSRI antidepressant medicine.

Cognitive behavioural therapy

What is CBT?

CBT is a type of specialist talking treatment (a specialist psychological therapy). It is probably the most effective treatment for OCD.

Cognitive therapy is based on the idea that certain ways of thinking can trigger, or fuel, certain mental health problems such as OCD. The therapist helps you to understand your current thought patterns - in particular, to identify any harmful, unhelpful, and false ideas or thoughts which you have. Also, to help your thought patterns to be more realistic and helpful. For example, if you have OCD, it may be helpful to understand that thoughts or obsessions in themselves do no harm, and you do not have to counter them with compulsive acts. The therapist suggests ways in which you can achieve these changes in thinking.

Behavioural therapy aims to change behaviours which are harmful or not helpful - for example, compulsions. The therapist also teaches you how to control anxiety when you face up to any feared situations - for example, by using breathing techniques.

Cognitive behavioural therapy (CBT) is a mixture of the two where you may benefit from changing both thoughts and behaviours. This is the most common treatment for OCD. A particular variation of CBT called exposure and response prevention is often used for OCD. For example, say you have a compulsion to keep washing your hands in response to an obsessional fear about contamination with germs. In this situation the therapist may gradually expose you to contaminated objects. But, the therapist prevents you from doing your usual compulsion (repeated hand washing) to ease your anxiety about contamination. Instead, the therapist teaches you how to control any anxiety in other ways - for example, by using deep breathing techniques. In time, you should become less anxious about contamination and feel less need to wash your hands so much.

How can I get CBT?

Your doctor may refer you to a therapist who has been trained in CBT. This may be a psychologist, psychiatrist, psychiatric nurse, or other healthcare professional. There is a limited number of CBT therapists available on the NHS and there may be waiting lists for therapists in some areas. However, government policy is to make CBT more widely available on the NHS.

Therapy is usually weekly sessions of about 50-60 minutes each, for several weeks. Sometimes this is done in a group setting or sometimes one-to-one, depending on various factors such as the severity of the problem. Sometimes, CBT is done by telephone conversations with a therapist. Occasionally, home-based treatment is offered to people who are unable or unwilling to attend a clinic, or who have a specific problem such as hoarding.

How effective is CBT for OCD?

Of those who complete a course of CBT, there is a marked improvement in more than 3 in 4 cases. Symptoms may not go completely, but usually the obsessions and compulsions become much less of a problem. About 1 in 4 people with OCD finds CBT too stressful and not for them. However, cognitive therapy alone may help some people who find the full CBT too stressful.

As a general rule, if two courses of CBT have failed to help, the person is referred to an OCD specialist.

Do-it-yourself CBT

CBT with the help of a trained therapist is best. However, some people prefer to tackle their problems themselves. There is a range of self-help books and leaflets on self-directed CBT. More recently, interactive CDs and websites are being developed and evaluated for self-directed CBT. See the resources below for further details.

See separate leaflet in this series, called Obsessions and Compulsions Self Help Guides. This may be a good start if you want to try self-directed CBT.

Medicines used to treat obsessive-compulsive disorder

SSRI antidepressants

Although they are often used to treat depression, SSRI antidepressant medicines can also reduce the symptoms of OCD, even if you are not depressed. They work by interfering with brain chemicals (neurotransmitters) such as serotonin, which may be involved in causing symptoms of OCD. SSRI antidepressants include: citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline.


  • SSRI antidepressants do not work straightaway. It takes 2-4 weeks before their effect builds up and starts to work. They may take up to 12 weeks to work fully. A common problem is that some people stop the medicine after a week or so, as they feel that it is doing no good. You need to give them time to work.
  • SSRI antidepressants are not tranquillisers, and are not usually addictive.
  • The doses needed to treat OCD are often higher than those needed for depression.
  • If it works, it is usual to take an SSRI antidepressant for at least a year to treat OCD.

What about side-effects with SSRIs?

Most people who take an SSRI have either minor, or no, side-effects. Possible side-effects vary between different preparations. The most common ones include: diarrhoea, feeling sick, vomiting, and headaches. Some people develop a feeling of restlessness or anxiety (see below). Sexual problems sometimes occur. It is worth keeping on with treatment if side-effects are mild at first. Minor side-effects may wear off after a week or so.

The leaflet that comes in the medicine packet gives a full list of possible side-effects. Tell your doctor if a side-effect persists or is troublesome. A switch to a different preparation may then suit you better. Drowsiness is an uncommon side-effect with SSRI antidepressants, but do not drive or operate machinery if you become drowsy whilst taking one.

SSRI antidepressants and suicidal behaviour

In recent years there have been some case reports which claim a link between taking SSRI antidepressants and feeling suicidal. The Commission on Human Medicines has recently reviewed the evidence on whether there is such a link. They were unable to find any convincing evidence of this link. The Committee on Human Medicines has stated that it will continue to monitor this issue.

Because of this possible link, see your doctor promptly if you become restless, anxious or agitated, or if you have any suicidal thoughts - in particular, if these develop in the early stages of treatment with an SSRI, or following an increase in dose.

Are SSRI antidepressants addictive?

SSRIs are not tranquillisers, and are not thought to be addictive. (This is disputed by some people, and so this is controversial. If addiction does occur, it is only in a minority of cases.) Most people can stop an SSRI without any problem. At the end of a course of treatment you should reduce the dose gradually over about four weeks before stopping. This is because some people develop withdrawal symptoms if the SSRI is stopped abruptly.

Withdrawal symptoms that may occur include: dizziness, anxiety and agitation, sleep disturbance, flu-like symptoms, diarrhoea, abdominal cramps, pins and needles, mood swings, feeling sick, and low mood. These symptoms are unlikely to occur if you reduce the dose gradually. If withdrawal symptoms do occur, they will usually last less than two weeks. An option if they do occur is to restart the medicine, and then reduce the dose even more slowly before stopping. You should see your doctor if you are worried that you are developing withdrawal symptoms.

Some other points about SSRIs and OCD

Symptoms can improve by up to 70% if you take an SSRI. So, although symptoms may not go completely, they usually greatly improve so the obsessions and compulsions are much less of a problem. This can make a big difference to your quality of life.

You should not stop SSRI antidepressants suddenly. You should gradually reduce the dose as advised by a doctor at the end of treatment. In some people the symptoms return when medication is stopped. An option then is to take an SSRI antidepressant long-term. However, symptoms are less likely to return once you stop an SSRI antidepressant if you have had a course of CBT (described earlier).

Reasons why medication may not work so well in some people include:

  • The dose is not high enough and needs to be increased.
  • Medication was not taken for long enough - it may take up to twelve weeks to work.
  • Side-effects became a problem and so you may stop the medication. Tell a doctor if side-effects are troublesome.

Other medicines that are used to treat obsessive-compulsive disorder

If SSRIs do not help much, or cannot be taken, then another type of antidepressant called clomipramine is sometimes used. This is classed as a tricyclic antidepressant and used to be the main medication treatment for OCD before SSRIs became available. Occasionally, other medicines that are used to treat mental health disorders are used.

Cognitive behavioural therapy plus selective serotonin reuptake inhibitor antidepressants

In some situations, a combination of CBT plus an SSRI antidepressant is advised. This may be better than either used alone when OCD is severe.

What is the prognosis (outlook) for obsessive-compulsive disorder?

If OCD is not treated, obsessive thoughts and compulsions may not improve and may get worse in some people. However, with treatment, many people's symptoms can be brought under control and some people may be completely cured.

If you have OCD, there is a risk that it can return even after successful treatment and recovery. If your symptoms do come back, be sure to see a doctor for further treatment.