Obsessive-compulsive disorder (OCD) is a common mental health problem. Symptoms typically include recurring thoughts and repetitive actions in response to the recurring thoughts. A common example is recurring thoughts about germs and dirt, with a need to wash your hands repeatedly to ‘clean off the germs’. However, there are many other examples.

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 (for example, 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 need 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 some life disruption 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 schoolwork in children), relationships, social life and 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.

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. Up to 2 in 100 children are also thought to have OCD. Read more about OCD in children and young people.

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?
  • What is the treatment for obsessive-compulsive disorder?

The usual treatment for OCD is:

1.Cognitive behavioural therapy (CBT); or

2.Medication, usually with a selective serotonin reuptake inhibitor (SSRI) antidepressant medicine; or

3.A combination of CBT plus an SSRI antidepressant medicine.

Cognitive behavioural therapy (CBT) for obsessive-compulsive therapy

Cognitive behavioural therapy is a type of therapy that deals with your current thought processes and/or behaviours and aims to change them by creating strategies to overcome negative patterns, which may help you to manage OCD more effectively. See separate leaflet called Cognitive Behavioural Therapy (CBT).

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 find 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.

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, 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, being sick (vomiting) and headaches. Some people develop a feeling of restlessness or anxiety (see below).