What is obsessive compulsive disorder (OCD)?

Anxious thoughts can influence our behaviour, which is helpful at times. For example, thinking 'I may have left the oven on' leads to you checking the oven and keeping things safe.

However, if that thought becomes obsessive (recurring), it can influence unhealthy patterns of behaviour that can cause difficulties in daily functioning. Obsessively thinking 'I've left the oven on' can lead to repeated checking.

For someone with the anxiety disorder known as obsessive compulsive disorder (OCD), obsessions or compulsions (acts performed to alleviate the distress or neutralise the thought), or both, are present.

People with OCD often feel intense shame about their need to carry out these compulsions. These feelings of shame can exacerbate the problem and the shame, and consequent secrecy associated with OCD can lead to a delay in diagnosis and treatment. It can also result in social disability, such as children failing to attend school or adults becoming housebound.

What are the signs and symptoms of OCD?

Issues that commonly concern people with OCD and result in compulsive behaviour include:
  • Cleanliness/order – obsessive hand-washing or household cleaning to reduce an exaggerated fear of contamination; obsession with order or symmetry, with an overwhelming need to perform tasks or place objects, such as books or cutlery, in a particular place and/or pattern
  • Counting/hoarding – repeatedly counting items or objects, such as their clothes or pavement blocks when they are walking; hoarding items such as junk mail and old newspapers
  • Safety/checking – obsessive fears about harm occurring to either themselves or others which can result in compulsive behaviours such as repeatedly checking whether the stove has been turned off or that windows and doors are locked
  • Sexual issues – having an irrational sense of disgust concerning sexual activity
  • Religious/moral issues – feeling a compulsion to pray a certain number of times a day or to such an extent that it interferes with their work and/or relationships.

People with OCD may also experience other mental health issues including depression, other anxiety disorders, an eating disorder and/or alcohol or substance-use problems.

Symptom checklist 

Have you:

  • had repetitive thoughts or concerns that are not simply about real life problems (e.g. thoughts that you or people close to you will be harmed)
  • Done the same activity repeatedly and in a very ordered, precise and similar way each time e.g.:
    • constantly washing your hands or clothes, showering or brushing your teeth
    • constantly cleaning, tidying or rearranging things at home, at work or in the car in a very particular way
    • constantly checking that doors and windows are locked and/or appliances are turned off
  • felt relieved in the short term by doing these things, but soon felt the need to repeat them
  • recognised that these feelings, thoughts and behaviours were unreasonable
  • found that these thoughts or behaviours take up more than one hour a day and/or interfered with your normal routine (e.g. working, studying or seeing friends and family)?

How common is OCD and who experiences it?

Close to 3 per cent of people in Australia experience OCD in their lifetime and approximately 2 per cent in a 12 month period.1

OCD can occur at any time during your life and children as young as six or seven may have symptoms, although symptoms seem to develop fully for the first time in adolescence.

What causes OCD?

OCD is thought to develop from a combination of genetic and environmental factors. A number of factors may increase the risk of developing OCD, including family history, social factors and psychological factors. Other factors specific to OCD include:

  • Biological factors – OCD has been linked to several neurological factors and irregular levels of serotonin (a chemical that transmits messages between brain cells) in particular. Research into chemical, structural and functional changes or abnormalities in the brain continues.
  • Environmental / learned behaviours – Some experts suggest that OCD may develop as a result of learned behaviour, either by direct conditioning (e.g. developing a washing compulsion after contracting a disease from contact with an animal) or learning by watching the behaviour of others, e.g. parents.

What treatments are available for OCD?

OCD is treatable and seeking professional support is the first step towards recovery. There are two main types of effective treatments for OCD — psychological treatments will generally be the first line of treatment. In some severe cases, medication can also be effective. 


1. For a full list of references for the statistics on this page, and any others across the website, please visit the references page and search through the relevant category.