Obsessive-compulsive disorder (OCD) is a mental health condition characterized by distressing, intrusive, obsessive thoughts and repetitive, compulsive physical or mental acts.

It is a distinct condition but falls within the category of “obsessive-compulsive and related disorders.”

Fast facts on obsessive-compulsive disorder

  • Common compulsions include washing, cleaning, checking, and repeating.
  • The American Psychiatric Association (APA) state that females are affected at a slightly higher rate than men, and that OCD affects people of all races and socioeconomic backgrounds.
  • Some people with OCD successfully hide their symptoms in fear of embarrassment or stigma.
  • Treatment options include therapy and medication.

What is OCD?

OCD is a mental health condition that centers around a debilitating obsession or compulsion, distressing actions, and repetitive thoughts.

A 2001 World Health Organization (WHO) mental health report estimated that OCD was among the top 20 causes of illness-related disability worldwide for people aged 15 to 44 years.

The report also suggested that OCD was the fourth most common mental illness after phobias, substance abuse, and major depression.

OCD is associated with a wide range of functional impairments and has a significant impact on social and working life.


There are several types of OCD that present in different ways.

Checking: This is a need to repeatedly check something for harm, leaks, damage, or fire. Checking can include repeatedly monitoring taps, alarms, car doors, house lights, or other appliances.

It can also apply to “checking people.” Some people with OCD diagnose illnesses they feel that they and the people close to them might have. This checking can occur hundreds of times and often for hours, regardless of any commitments the individual may have.

Checking can also involve repeatedly confirming the authenticity of memories. A person with OCD might repeatedly validate letters and e-mails for fear of having made mistakes. There may be a fear of having unintentionally offended the recipient.

Contamination or mental contamination: This occurs when a person with OCD feels a constant and overbearing need to wash and obsesses that objects they touch are contaminated. The fear is that the individual or the object may become contaminated or ill unless repeated cleaning takes place.

It can lead excessive toothbrushing, overcleaning certain rooms in the house, such as the bathroom or kitchen, and avoiding large crowds for fear of contracting germs.

Mental contamination is the feeling of being ‘dirty’ after being mistreated or put down. In this type of contamination, it is always another person that is responsible. A person with OCD will try to ‘scrub away’ this feeling by showering and washing excessively.

Hoarding: This is the inability to throw away used or useless possessions.

Rumination: Ruminating involves an extended and unfocused obsessive train of thought that focuses on wide-ranging, broad, and often philosophical topics, such as what happens after death or the beginning of the universe.

The person may seem detached and deep in thought. However, the ruminating never reaches a satisfactory conclusion.

Intrusive thoughts: These are often violent, horrific, obsessional thoughts that often involve hurting a loved one violently or sexually.

They are not produced out of choice and can cause the person with OCD severe distress. Because of this distress, they are unlikely to follow through on these thoughts.

These thoughts can include obsessions about relationships, killing others or suicide, a fear of being a pedophile, or being obsessed with superstitions.

Symmetry and orderliness: A person with OCD may also obsess about objects being lined up to avoid discomfort or harm. They may adjust the books on their shelf repeatedly so that they are all straight and perfectly lined up, for example.

While these are not the only types of OCD, obsessions and compulsions will generally fall into these categories.


OCD is separated from other mental health conditions by the presence of obsessions, compulsions, or both. The obsessions or compulsions cause marked distress, are time-consuming, and interfere with a person’s normal function.

Indications of OCD can occur in children and teenagers, with the disease usually beginning gradually and worsening with age. Symptoms of OCD can be mild or severe. Some people experience obsessive thoughts only, without engaging in compulsive behavior.

Some people who experience OCD successfully hide their symptoms for fear of embarrassment or stigma. Friends and family may, however, notice some of the more physical signs.


Obsessions are more than the everyday worries experienced by most healthy people when thinking about real-life problems. Instead, people with OCD experience excessive thoughts and worries that prompt them to engage in particular actions or thoughts in an attempt to relieve or suppress the fear and anxiety.

A person with OCD typically:

  • has repetitive thoughts, images, or urges that they do not feel able to control
  • is aware of these intrusive thoughts and feelings and does not want to have these ideas
  • finds these thoughts disturbing, unwanted, and, in the case of older children and adults, is aware that they do not make sense
  • has uncomfortable feelings, such as fear, disgust, doubt, or a feeling that things have to be done in a way that is “just right”
  • spends an unwarranted amount of time on these obsessions, which interferes with personal, social, and professional activities

Common OCD obsessions include:

  • contamination, including body fluids, germs, and dirt
  • losing control, including a fear of acting on an urge to harm one’s self or others
  • perfectionism, including concerns about exactness, needing to remember things, and fear of losing things
  • harm, including a fear of being responsible for something terrible happening
  • unwanted sexual thoughts, including obsessions about homosexuality or incest
  • religious obsessions, including concerns about offending God


Not all “rituals” or forms of repetitive behavior are compulsions. Normal repetitive behaviors that feature in everyday life may include bedtime routines, religious practices, and learning a new skill.

Behavior also depends on the context. For example, a person who works in a video store arranging DVDs for 8 hours a day is probably not acting out of compulsion.

Common OCD compulsions include:

  • washing and cleaning, including constant hand-washing
  • checking, including checking body parts or checking that nothing terrible happened
  • repeating, including rereading and repeating routine activities like getting up from a chair.
  • mental compulsions, including praying to prevent harm and mentally reviewing events


Despite a wealth of research, the exact causes of OCD have not been identified.

OCD is thought to have a neurobiological basis, with neuroimaging studies showing that the brain functions differently in people with the disorder. An abnormality, or an imbalance in neurotransmitters, is thought to be involved in OCD.

The disorder is equally common among adult men and women.

OCD in children

OCD that begins in childhood is more common in boys than girls, with the usual time of onset of OCD later for females than males.

The condition might be triggered by a combination of genetic, neurological, behavioral, cognitive, and environmental factors.

Genetic causes

OCD runs in families and can be considered a “familial disorder.” The disease may span generations with close relatives of people with OCD significantly more likely to develop OCD themselves.

Twin studies of adults suggest that obsessive-compulsive symptoms are moderately able to be inherited, with genetic factors contributing 27 to 47 percent variance in scores that measure obsessive-compulsive symptoms. However, no single gene has been identified as the “cause” of OCD.

Autoimmune causes

Some rapid-onset cases of OCD in children might be consequences of Group A streptococcal infections, which cause inflammation and dysfunction in the basal ganglia.

These cases are grouped and referred to as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS).

In recent years, however, other pathogens, such as the bacteria responsible for Lyme disease and the H1N1 flu virus, have also been associated with the rapid onset of OCD in children. As such, clinicians have altered the acronym to PANS, which stands for Pediatric Acute-onset Neuropsychiatric Syndrome.

Behavioral causes

The behavioral theory suggests that people with OCD associate certain objects or situations with fear. They learn to avoid those things or learn to perform “rituals” to help reduce the fear. This fear and avoidance or ritual cycle may begin during a period of intense stress, such as when starting a new job or just after an important relationship comes to an end.

Once the connection between an object and the feeling of fear becomes established, people with OCD begin to avoid that object and the fear it generates, rather than confronting or tolerating the fear.

Cognitive causes

The behavioral theory outlined above focuses on how people with OCD make an association between an object and fear. The cognitive theory, however, focuses on how people with OCD misinterpret their thoughts.

Most people have unwelcome or intrusive thoughts at certain times, but for individuals with OCD, the importance of those thoughts are exaggerated.

For example, a person who is caring for an infant and who is under intense pressure may have an intrusive thought of harming the infant either deliberately or accidentally.

Most people can shrug off and disregard the thought, but a person with OCD may exaggerate the importance of the thought and respond as though it signifies a threat. As long as the individual with OCD interprets these intrusive thoughts as cataclysmic and true, they will continue the avoidance and ritual behaviors.

Neurological causes

Brain imaging techniques have allowed researchers to study the activity of specific areas of the brain, leading to the discovery that some parts of the brain are different in people with OCD when compared to those without.

Despite this finding, it is not known exactly how these differences relate to the development of OCD.

Imbalances in the brain chemicals serotonin and glutamate may play a part in OCD.

Environmental causes

Environmental stressors may be a trigger for OCD in people with a tendency toward developing the condition.

Traumatic brain injury (TBI) in adolescents and children has also been associated with an increased risk of onset of obsessive-compulsions. One study found that 30 percent of children aged 6 to 18 years who experienced a TBI developed symptoms of OCD within 12 months of the injury.

Overall, studies indicate that people with OCD frequently report stressful and traumatic life events before the illness begins.


According to the American Psychiatric Association (APA), the diagnostic criteria for OCD include:

  • the presence of obsessions, compulsions or both
  • the obsessions and compulsions are time-consuming or cause clinically significant distress or impairment in social, occupational, or other important areas of functioning
  • the obsessive-compulsive symptoms are not due to the physiological effects of a substance, for example, drug abuse or medication for another condition.
  • the disturbance is not better explained by another mental disorder

If the above criteria are met, a diagnosis of OCD might be given.

A number of other psychiatric and neurological disorders, such as depression and anxiety, have similar features to OCD and can occur alongside the condition.


OCD usually develops into a chronic condition if left untreated, with episodes where symptoms seem to improve. Without treatment, remission rates are low, at around 20 percent.

However, around 40 percent of people who develop OCD in childhood or adolescence experience remission by early adulthood. Treatment for OCD will depend on how much the condition affects the person’s ability to function.

First-line treatments for OCD will often include:

  • cognitive behavioral therapy (CBT)
  • selective serotonin reuptake inhibitors (SSRI)
  • a combination of SSRI and CBT

Cognitive behavioral therapy

CBT is an effective method of treating OCD. CBT is a type of psychotherapy (talking therapy) that aims to help the individual change the way they think, feel, and behave. It refers to two distinct treatments:

  • exposure and response prevention (ERP)
  • cognitive therapy

Research has shown that 75 percent of people with OCD are significantly helped by cognitive behavioral therapy. Treatment techniques include exposure and response prevention (ERP), this involves the following:

  • Exposure: This involves exposure to situations and objects that trigger fear and anxiety. Over time, the anxiety generated by these obsessional cues decreases and, eventually, the obsessional cues cause little or no anxiety. This is called habituation.
  • Response: Response prevention refers to the ritual behaviors that people with OCD engage in to reduce anxiety. This treatment helps people learn to resist the compulsion to perform these rituals.

Other techniques focus solely on cognitive therapy. People who participate in this type of therapy work toward eliminating the compulsive behavior. This is done by identifying and re-evaluating their beliefs about the consequences of engaging, or not engaging, in the compulsive behavior.

Once these intrusive thoughts and the meanings the person applies to them are acknowledged, the therapist will then encourage the person to:

  • examine the evidence that supports and does not support the obsession
  • identify cognitive distortions in the appraisals of the obsession
  • develop a less threatening and alternative response to the intrusive thought, image, or idea

Only a small number of studies have tested the effectiveness of CT for OCD. These studies have, however, found CT to be effective.


There are a number of drugs available for treating OCD, with the development of SSRIs expanding the range of treatment options. SSRIs that may be prescribed to help people manage OCD include:

  • clomipramine
  • fluoxetine
  • fluvoxamine
  • paroxetine hydrochloride
  • sertraline
  • citalopram
  • escitalopram

SSRIs are generally used in higher doses for OCD than for depression. It might take up to 3 months for results to be noticed.

About half of all people with OCD do not respond to SSRI treatment alone, with atypical antipsychotic medications often added to the treatment.


Without treatment, mild OCD can improve, but moderate-to-severe OCD will not improve and often gets worse.

Successful treatment can significantly improve and even cure OCD. However, the condition can return later on.

The outlook for OCD is generally good, and treatment is often effective.