Pure O, short for Purely Obsessional OCD, is a term used to describe a presentation of obsessive-compulsive disorder (OCD) in which someone experiences distressing intrusive thoughts, doubts or other unwanted mental experiences, but doesn't appear to perform any obvious compulsions. It's a rather snazzy term, and one that's becoming increasingly familiar in discussions about OCD.
But I have a bit of a problem with it. In fact, I think it's something of a misnomer. The term suggests that someone is experiencing the obsessive part of OCD without the compulsive part. But in my experience, the compulsions are usually very much present. They're simply happening inside the person's head.
What does Pure O actually look like?
Most people associate OCD with visible compulsions, such as repeatedly washing their hands, checking locks or arranging things in a particular way. But compulsions don't have to involve physical actions. They can also involve thinking. For example, someone might experience an intrusive doubt about whether they really love their partner (relationship OCD). Rather than repeatedly checking something physically, they might spend hours analysing their feelings, reviewing memories of the relationship or trying to work out whether their attraction is genuine. Or someone might suddenly remember something they did years ago and become preoccupied with whether it was wrong (real event OCD). They might repeatedly replay the memory, examine their intentions, reconstruct what happened or try to establish whether they're a bad person. To an observer, there may be no obvious sign that anything is happening. But internally, the person can be engaged in an exhausting cycle of repetitive thinking. These are mental compulsions.
Other examples include mentally reassuring ourselves, trying to replace unwanted thoughts with acceptable ones, checking our emotional reactions or repeatedly analysing what an intrusive thought might mean. And these behaviours can be every bit as consuming as more recognisable physical compulsions.
Isn't obsessing just another form of compulsion? This is where I find the terminology particularly confusing. We often describe people with OCD as obsessing over something. But what do we actually mean by obsessing? In everyday language, we might mean repeatedly thinking about something, analysing it, revisiting it or being unable to leave it alone. And in OCD, that process of repetitive analysis can itself be compulsive. For example, in real event and harm OCD, someone might experience an unwanted thought:
What if I've hurt somebody?
That initial thought may appear completely spontaneously. But what follows? They begin reviewing what happened, checking their memories, looking for evidence and trying to establish whether the fear could be true. The original intrusive thought becomes a subject of obsessional introspection. The repeated attempts to analyse and resolve it can become compulsions. Of course, not all repetitive thinking is a compulsion. Intrusive thoughts can recur involuntarily, and ordinary reflection or problem-solving is not inherently problematic. The key distinction is whether we repeatedly engage with a thought to gain certainty, reduce distress, or neutralise a perceived threat. That's often where rumination becomes part of the OCD cycle.
I've explored this in more detail in my article When Does Rumination Become a Compulsion?.
Should OCD actually be called Intrusive Compulsive Disorder?
If I were responsible for naming OCD, I sometimes think I'd have called it Intrusive Compulsive Disorder instead. ICD. Admittedly, it doesn't have quite the same ring to it. But I think it might explain what's happening more clearly. People experience intrusive thoughts, doubts, feelings, images, memories or sensations. These experiences can feel particularly distressing because of the meaning we attach to them.
What does having this thought say about me?
What if it means I'm dangerous?
What if I've made a terrible mistake?
What if this feeling means something is wrong?
We then respond compulsively, trying to eliminate the doubt, neutralise the thought, reduce discomfort or prevent a feared outcome. The more we respond this way, the more important the intrusive experience can seem. The condition becomes self-perpetuating. The problem isn't simply that we're having intrusive experiences. It's the significance they acquire and the compulsive responses that can follow. After all, intrusive thoughts and doubts are a normal part of being human. Experiencing them doesn't automatically mean someone has OCD.
Is Pure O a particular subtype of OCD?
Not really. Pure O isn't a separate formal diagnosis. It's an informal description of an OCD presentation in which compulsions are less obvious, particularly because many of them are mental. It's often associated with themes such as relationship OCD and real event OCD, where someone may spend considerable time analysing feelings, reviewing memories or trying to resolve uncertainty. But mental compulsions can occur with almost any OCD theme. Someone experiencing harm OCD might repeatedly analyse their intentions, while somebody with contamination OCD might mentally review whether they've touched something dangerous. Personally, I find it more useful to understand someone's particular OCD theme, the meaning they attach to their intrusive experiences and the compulsions they use in response. That gives us a much clearer understanding of how their OCD operates than simply describing it as Pure O.
Don't overlook the less obvious physical compulsions
There's another reason I'm cautious about using the term Pure O. Sometimes compulsions aren't exclusively mental. They're just subtle. Someone might repeatedly Google a question, ask friends for reassurance, check their bodily reactions, avoid particular situations or subtly test their feelings. They may not recognise these behaviours as compulsions because they don't resemble the familiar rituals associated with OCD. This is why a careful assessment is important. We need to understand the full range of responses someone is using, rather than assuming their OCD involves thinking alone.
How is Pure O treated?
Fortunately, the distinction doesn't fundamentally change the treatment approach. Cognitive Behavioural Therapy (CBT), including Exposure and Response Prevention (ERP), remains a recommended psychological treatment for OCD. However, when compulsions are predominantly mental, treatment needs to pay particular attention to those internal processes. Someone may need to practise allowing intrusive thoughts and doubts to remain unresolved without analysing them, reviewing memories, mentally reassuring themselves or checking how they feel. This can be challenging because mental compulsions are often deeply habitual and difficult to recognise. But learning to identify and gradually reduce these responses can be a powerful part of overcoming OCD.
My opinion
Pure O is a catchy term, but I don't find it particularly helpful. It can give the impression that someone experiences intrusive thoughts without compulsions, when in reality their compulsions may simply be less visible. And focusing too heavily on the distinction between Pure O and other presentations can distract us from something more important: understanding the intrusive experiences, compulsions and behaviours that keep the individual trapped in their OCD cycle. You don't need to see a compulsion for it to be happening. And recognising the compulsions that take place inside our minds can be an important first step towards changing them.
Looking for help with OCD?
I offer individual CBT and ERP therapy online across the UK, alongside a comprehensive self-guided OCD treatment programme. If you recognise some of these patterns in your own experience, feel free to get in touch to discuss whether therapy might help.