Pure O OCD: when the compulsions happen inside your head

What is Pure O?

"Pure O" (purely obsessional OCD, sometimes "pure OCD") is an informal name for OCD in which the compulsions happen mostly inside your head: mentally reviewing, checking how you feel, arguing with a thought, praying, or reassuring yourself. It isn't a separate diagnosis and it isn't truly "pure". The mental rituals are compulsions, and they're treated with ERP like any other.

Where the term comes from, and why clinicians avoid it

"Pure O" grew up in online OCD communities to describe people whose OCD didn't look like the stereotype. No washing, no checking the locks, no lining things up. Just a relentless stream of disturbing thoughts and an exhausted mind trying to deal with them. The term gave a lot of people a name for something they thought was unique to them, and that was useful.

The trouble is the word "pure". When researchers looked closely at people whose OCD was dominated by taboo obsessions, the compulsions were there; they were just mental. In one study of 201 adults with OCD, more than half of those with aggressive obsessions, nearly two thirds with sexual obsessions and nearly half with religious obsessions reported mental compulsions, and a proportion also sought reassurance from others. Mental rituals and reassurance seeking clustered statistically with these obsessions, which is why the authors titled their paper the "myth of the pure obsessional type".

This matters for treatment. If you believe you have obsessions but no compulsions, you have nothing to stop doing, and ERP seems irrelevant. Once you can see the rituals, the treatment plan becomes obvious.

The compulsions you can't see

A compulsion is anything you do, in the world or in your mind, to reduce the distress of an obsession or to gain certainty about it. In "Pure O" the list usually includes several of these:

• Mental review. Replaying the drive home frame by frame to check you didn't clip a cyclist. Re-running the conversation at the barbecue to be sure you didn't say something offensive.
• Checking your feelings or body. Monitoring whether you felt a flicker of attraction, anger or arousal, then analysing what it means. In sexual-themed OCD this often includes checking for a physical response, which is itself enough to create one.
• Arguing with the thought. Marshalling evidence that you'd never do it, that you're not that kind of person, that you've always been gentle. OCD counters every point.
• Neutralising. Replacing a "bad" image with a "good" one, counting, repeating a phrase, silently praying until it feels right.
• Self-reassurance. "It's fine, it's just OCD, I'd never do that." Research finds people with OCD reassure themselves more than people with other anxiety problems, and it works in exactly the same way as asking someone else.
• Reassurance from others, confessing and googling. Asking your partner whether you seem normal. Confessing a thought so someone can tell you it's okay. Searching "can OCD make you a bad person" for the fortieth time.
• Avoidance. Not holding the baby, skipping the news, avoiding the friend the thoughts attach to, leaving church.

A useful test: obsessions arrive on their own and you'd give anything to be rid of them. Compulsions are things you do, however automatic, to feel better. If it's voluntary and it brings relief, it's a ritual.

Common forms of Pure O

Mental compulsions can attach to any obsession, but some themes are especially likely to run without visible rituals:

• Harm. Thoughts of hurting a partner, child or stranger, with constant mental checking that you don't want to. See harm OCD.
• Sexual. Unwanted sexual thoughts about children or family members, or persistent doubt about your sexual orientation that contradicts your actual experience and attractions.
• Relationship. "Do I really love them?" "Are they right for me?" tested and re-tested all day. See relationship OCD.
• Religious and moral. Blasphemous thoughts, fear of having sinned, or hours of reviewing whether you were perfectly honest. See scrupulosity.
• Existential and "real event". Looping on whether anything is real, or on a real thing you did at 15, searching for proof you're not a bad person.

Our page on intrusive thoughts covers why these thoughts stick in OCD and why their content reflects your values rather than your intentions.

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Why Pure O is so often missed

NICE notes that less common forms of OCD can go unrecognised for years, and that relatively few GPs or mental health professionals have expertise in them. Pure O is a prime example. From the outside, someone with mostly mental compulsions looks anxious, distracted or low. They may be treated for depression or generalised anxiety, or told they're "overthinking", while the real engine goes unnoticed.

Shame does the rest. If your intrusive thoughts are about hurting children or about sex, you may never have said them aloud, and a clinician who doesn't ask the right questions won't hear them. Some people have been in therapy for years without their OCD being named, because the sessions were spent reassuring them, which is comforting in the room and corrosive outside it.

If you've read this far and recognised yourself, that recognition is a good start. A psychologist trained in OCD will ask directly about taboo thoughts and mental rituals, and will not be shocked by the answers.

How ERP treats mental rituals

Exposure and response prevention is the recommended psychological treatment for OCD in every major guideline, and it applies to mental compulsions just as it does to washing or checking. The adaptation is in the method.

Exposure. Because the trigger is a thought, you bring the thought on deliberately. That might mean writing a short, vivid script of the feared scenario and reading it daily, recording it in your own voice and listening on the bus, saying the feared sentence out loud ("maybe I am attracted to them"), or spending time with the person or situation the thoughts attach to without escaping.

Response prevention. This is the harder half. You learn to notice the moment a mental review, a self-reassurance or an argument starts, and to drop it mid-sentence, leaving the question open. "Maybe, maybe not" replaces "let me just make sure". Early on this feels like leaving a tap running. Over weeks it becomes a skill.

Cognitive work. Alongside ERP, you examine the beliefs that give mental rituals their job: that you must know for certain, that a thought reveals a wish, that you're responsible for every image that crosses your mind. Acceptance-based approaches like ACT add practice at letting a thought sit there, unanswered, while you cook dinner.

The step-by-step process is on our ERP therapy page. Trying to suppress the thoughts, by contrast, tends to backfire: a meta-analysis of controlled studies found suppression produces a rebound, with the thought returning more often.

Treatment for Pure O at Mindwell, online

Pure O is well suited to video sessions. Nothing about the work requires a clinic, and much of it benefits from being in your own environment, where the thoughts actually arrive. Your psychologist can sit with you through an exposure script in real time, watch for the moment you slip into reviewing, and help you drop it.

A course typically runs 12 to 20 sessions of 50 minutes, weekly at first. Mindwell's psychologists are registered with the New Zealand Psychologists Board and work with adults 18+ anywhere in New Zealand. Sessions are $199 + GST ($228.85 incl. GST), booked online with no referral. Not sure whether what you're experiencing is OCD? Begin with an OCD assessment, where a psychologist will ask about the thoughts and the rituals directly.

Related support: OCD treatment · Intrusive thoughts · Harm OCD · ERP therapy