'Pure O': An Overview of Pure Obsessional OCD

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Pure O, also known as purely obsessional OCD, is a form of OCD marked by intrusive, unwanted, and uncontrollable thoughts (or obsessions). While someone experiencing Pure O may not engage in obvious behaviors related to their intrusive thoughts, such as counting, arranging, or hand-washing, the disorder is instead accompanied by hidden mental rituals.

Pure O is sometimes mistakenly seen as a “less severe” form of OCD. For those who experience symptoms of this disorder, the characteristic intrusive thoughts can be very disruptive and distressing.

While people who do not report engaging in compulsions are sometimes referred to as having "pure O" or "purely obsessional OCD," this variant is not listed as a separate diagnosis in the DSM-5, the diagnostic manual used by many physicians, psychiatrists, and psychologists.

Pure O vs. OCD

While some studies have suggested there may be different subtypes of OCD, others suggest that the term "pure O" may be something of a misnomer. While people who experience these obsessions without any obvious behavioral compulsions, they do still engage in rituals that are mental and unseen.

"Recognition of compulsions performed by those previously considered purely obsessional can aid in the improved diagnosis and treatment of people with OCD," explains clinical psychologist Monnica T. Williams and her colleagues in their article "The Myth of the Pure Obsessional Type in Obsessive-Compulsive Disorder."

By understanding that such mental rituals exist, therapists and other mental health professionals can ask patients about these symptoms. Without such questioning and prompting, patients may be reluctant to describe the symptoms that they are experiencing or may not even be aware that they should discuss these symptoms.

Symptoms of Pure O

Obsessive-compulsive disorder itself involves having reoccurring obsessions and behaviors (compulsions). For example, a person with OCD might have uncontrollable thoughts about germs and cleanliness that result in an urge to wash their hands over and over again.

People who experience a "purely obsessional" form of this disorder still experience a range of OCD symptoms, although the obvious compulsions are absent. According to the DSM-5, OCD is characterized by obsessions and/or compulsions.

  • Repeated intrusive images, thoughts, and impulses that create a great deal of distress

  • Making attempts to ignore, suppress, or neutralize the obsessive thoughts

  • Repetitive actions, either behavioral or mental, that a person feels compelled to perform as a result of obsessive thoughts

  • Engaging in actions intended to reduce distress related to the obsessions or preventing some dreaded event


Obsessions are recurrent, persistent, intrusive, and unwanted thoughts, images, or urges that cause anxiety or distress. Obsessions often center on somatic, sexual, religious, or aggressive thoughts as well as concerns with things such as symmetry and contamination.


Compulsions, on the other hand, are repetitive behaviors or mental acts a person with OCD is driven to perform in response to an obsession or according to a rigid set of rules that govern them. Compulsions are clearly excessive or not connected in a realistic way to the problem they are intended to address.

In a 2011 study, researchers found that individuals who experience the "pure obsessions" (sometimes described as "taboo thoughts" or "unacceptable thoughts") also engage in mental rituals as a way of managing their distress. These rituals might include:

  • Mentally reviewing memories or information
  • Mentally repeating certain words
  • Mentally un-doing or re-doing certain actions

People distressed by obsessive thoughts may also compulsively seek reassurance. This can be problematic because many patients may not even recognize it as a compulsion. Such reassurance-seeking may involve:

  • Asking others for assurance
  • Avoiding anxiety-provoking objects or situations
  • Looking for self-assurance
  • Researching online

An added complication of this symptom is that family and friends may become fatigued or annoyed by these constant requests for reassurance, which may be perceived by others as neediness.

Compulsions still exist in pure O, but they are much less obvious because they are almost entirely mental in nature.

Getting Diagnosed

In addition to experiencing obsessions and/or compulsions, the DSM-5 diagnostic criteria for OCD also stipulate the following:

  • OCD symptoms must not be due to the physiological effects of a substance (such as a side effect of a medication or illicit drug). The symptoms must also not be due to the presence of some other medical condition.
  • OCD symptoms are time-consuming, often taking more than one hour per day, or they must create significant distress or impairment in occupational, social, or other critical areas of life functioning.
  • OCD symptoms are not better attributable to another mental disorder such as generalized anxiety disorder, body dysmorphic disorder, hoarding disorder, substance-related disorders, or major depressive disorder.

If you or someone you love are experiencing distressing symptoms that keep you from participating in everyday activities (such as eating, sleeping, or going to work), contact a mental health professional.

Although there is limited research on the exact causes of pure O, there are a variety of studies that have investigated OCD and its causes. These may include:

  • Biological factors: MRI brain scans reveal structural and functional differences in neuronal (nerve) circuits in the brains that filter or "censor" the many thoughts, ideas, and impulses that we have each day.
  • Family history: Research has been difficult due to the inability to recruit "pure" cases of OCD. However, studies have found pure O to be five to seven times more common in people who have relatives with OCD.
  • Genetics: While researchers have yet to determine a single "OCD gene," the disorder may be related to variations in particular groups of genes.

Other Types of OCD

Previous research suggests there may be as many as three to six subtypes of OCD, including the pure O form of the disorder. First described in a 1994 article in the Journal of Clinical Psychiatry, pure O was described as being composed of sexual, aggressive, and religious obsessions that were not accompanied by compulsions.

Later, research further divided aggressive obsessions into fears over impulsive harm and unintentional harm. Those thoughts centered on impulsive harm often focus on what is sometimes termed "taboo thoughts" related to sex, religion, and aggression. Some common types of OCD experienced by those with pure O might include:

  • Harm OCD: Fears about causing harm to oneself or others; variations include physical harm (aggression toward or killing oneself or another) and sexual harm, including harmful sexual behavior toward children
  • Pedophilia OCD (pOCD): Unwanted sexual thoughts and urges related to children, sometimes accompanied by rituals such as counting, washing, or prayers to "neutralize" such thoughts and urges
  • Relationship OCD (ROCD): Unwanted, intrusive thoughts that make people doubt their feelings of attraction or love for their partner as well as their own level of sexual desirability or long-term compatibility
  • Sexual orientation obsessions in OCD (SO-OCD): Extreme anxiety about sexual orientation; also called HOCD, or "homosexual OCD."

Treatment for Pure O

Treatment for OCD, including pure O, often involves the use of medication in combination with psychotherapy, which can include cognitive-behavioral therapy (CBT), support groups, and psychological education.


Research suggests that cognitive-behavioral therapy can be very effective at treating pure O. However, it is essential that therapists and other mental health practitioners understand the importance of addressing the underlying mental rituals that characterize this subtype of OCD.

If the therapist believes that the patient only suffers from obsessions and does not also treat the mental rituals that accompany these cognitions, the treatment will not be as complete or effective.

In 2011, researchers examined individual studies to see if certain symptom subtypes of OCD responded better to particular treatment approaches. They found that in the majority of studies, OCD characterized by religious and sexual obsessions without compulsions (i.e., pure O) was associated with a poor response to treatments using SSRIs and exposure and response prevention.

Exposure and response prevention, also known as ERP therapy, is a form of behavioral therapy also used in the treatment of other presentations of OCD. It involves a trained therapist helping a client approach a fear object without engaging in any compulsive behaviors.

Clients intentionally expose themselves to those things that trigger their obsessions or compulsions but are prevented from engaging in compulsive behavior or obsessive thoughts. The goal of such therapy is to teach patients how to manage their symptoms without acting upon compulsions. This increases distress in the short term, but can improve symptoms and behaviors over time.


Medications may include selective serotonin reuptake inhibitors (SSRIs) or the tricyclic antidepressant Anafranil (clomipramine). Second-generation antipsychotics, also known as atypical antipsychotic medications, are also used to augment SSRIs. One review suggested that approximately 40% to 60% of patients respond to treatment with SSRIs with a 20% to 40% reduction in OCD symptoms.

The specific treatment (or combination of treatments) depends on a patient's particular needs. For example, a therapist may use CBT alone if a patient is unable to or doesn't want to take medication. Or, they might prescribe medications alone to patients who aren't motivated to pursue exposure-based treatments or who don't have access to a CBT provider.


Although treatment for OCD usually entails consulting with a qualified mental health professional, there are a number of OCD self-help strategies that you can start using right now to help you or someone you love cope with pure O symptoms.

  • Relaxation strategies: Given that stress is a major trigger of pure O symptoms, one of the best ways to cope is to learn and practice relaxation techniques such as deep breathing, mindfulness meditation, or progressive muscle relaxation.
  • Exercise: There is growing evidence that engaging in aerobic exercise can reduce the symptoms of OCD. 
  • Support groups: Both online and in-person support groups can be of enormous benefit for people with pure O (as well as their loved ones) by providing resources, information, or simply a compassionate, listening ear.

Pure O may not involve the outward behaviors that often come to mind when people think of OCD. However, the hidden mental rituals that characterize the purely obsessional form of the disorder are a type of compulsion, even though they may go unseen.

If you find yourself experiencing distressing obsessions and/or mental compulsions that are interfering with your daily life, consider talking to a mental health professional. They can help you understand your symptoms and find the best treatment to meet your needs. Though talking about your thoughts isn't always easy, it is the first part of getting the help you may need to find relief.

If you or a loved one are struggling with Pure O, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

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Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Kendra Cherry, MSEd
Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."