One of the most confusing aspects of Obsessive-Compulsive Disorder is that it can look so different from one person to the next. The underlying psychological pattern—the vicious cycle of obsession and compulsion—is always the same. However, the content of the obsessions can latch onto almost any theme imaginable.
These themes are often referred to as OCD “subtypes.” This is an informal term, but it’s a helpful way to categorise the different ways OCD can manifest. It’s important to know that you can experience one primary theme, or your theme can shift and change over time. Many people experience features of several different subtypes.
Finding your own experience described below can be a powerful moment of recognition. It’s proof that you are not alone, you are not “going crazy,” and what you are dealing with is a well-understood condition.
Contamination OCD
This is perhaps the most widely recognised subtype, but it goes far beyond a simple preference for cleanliness.
- The Obsessions: The core fear revolves around the threat of contamination. This can be a fear of germs, viruses (like COVID-19), dirt, or bodily fluids. It can also be a fear of chemical contaminants like household cleaners or even more abstract things like “bad luck,” “evil,” or the negative essence of a person. The ultimate fear is often of causing serious illness or death to oneself or, more commonly, to a loved one.
- The Compulsions: The rituals are aimed at washing, cleaning, and avoiding. This can look like washing hands until they are cracked and bleeding, multi-hour showering routines, excessively cleaning household surfaces, and avoiding public places like toilets, cinemas, or public transport. People with contamination OCD may also create “clean” and “contaminated” zones in their homes and ask family members to follow complex decontamination rituals.
Checking OCD
This subtype is driven by a profound and pathological doubt, coupled with an inflated sense of responsibility for preventing harm.
- The Obsessions: The thoughts centre on the possibility of having been negligent and causing a catastrophe. Common themes include fears of having left a door unlocked (leading to a break-in), an appliance on (leading to a fire), or having made a critical mistake in an email or document (leading to professional ruin). A particularly distressing form involves the fear of having hit someone while driving.
- The Compulsions: The primary compulsion is repetitive checking. This can involve physically returning to check locks, stoves, and taps dozens of times. It can also be mental, such as mentally reviewing every second of a car journey, or covert, like rereading an email endlessly before sending. Seeking reassurance from others (“Are you sure I turned the oven off?”) is also a very common checking compulsion. The tragedy of checking OCD is that each check erodes the person’s trust in their own memory, making the doubt even stronger next time.
Harm OCD & Unwanted Intrusive Thoughts (“Pure O”)
This is one of the most misunderstood and shame-inducing forms of OCD. It is crucial to understand the following: having these thoughts does not mean you are a dangerous person. In fact, it’s the opposite.
- The Obsessions: This subtype involves intrusive, unwanted, and horrific thoughts, images, or urges about causing harm. Often, these thoughts are directed at the people the sufferer loves most. The content can be violent (fears of stabbing or pushing someone), sexual (fears of being a paedophile or having an incestuous impulse), or otherwise taboo.
- The “Pure O” Myth: The term “Purely Obsessional” is a misnomer. The compulsions are very real, but they are almost entirely covert (mental). They include:
- Mental Review: Constantly scanning your memories and feelings for “evidence” that you might be a bad person.
- Thought Suppression: A desperate, and always failing, attempt to block or push the thoughts away.
- Reassurance Seeking: Asking others if they think you are a good person or googling the difference between intrusive thoughts and genuine intent.
- Avoidance: Actively avoiding triggers, such as hiding kitchen knives, avoiding being alone with children, or staying away from high places.
The distress comes from the ego-dystonic nature of these thoughts. They are terrifying precisely because they are so antithetical to your true character and values.
Scrupulosity (Religious & Moral OCD)
This subtype hijacks a person’s faith or moral code, turning it from a source of comfort into a source of immense fear and anxiety.
- The Obsessions: The thoughts centre on a fear of being morally corrupt or having offended God. This can involve intrusive blasphemous thoughts during prayer, an obsessive fear of having committed an unpardonable sin, or a paralysing need to be perfectly honest and righteous in every single action, no matter how small.
- The Compulsions: Rituals can include repetitive prayer (often to “cancel out” a bad thought), compulsive confession to religious leaders, seeking constant reassurance about one’s moral state, and mentally reviewing past actions to check for sins. Sufferers may also avoid religious services or symbols, fearing they will trigger an intrusive thought.
The Common Thread and The Path Forward in Ireland
While the themes described above seem vastly different, it is essential to remember that the underlying psychological engine is identical for all of them. The treatment, therefore, is also the same.
Exposure and Response Prevention (ERP) is the gold-standard, evidence-based therapy for all subtypes of OCD. The principles of ERP are adapted to the specific fear. For example, exposure for Harm OCD does not involve acting on a thought; it involves things like holding a knife or writing a script about the feared scenario to learn that the thoughts have no power and the anxiety will fade without a compulsion.
It is vital to find a therapist with specific expertise in treating the full spectrum of OCD themes. General counselling can be ineffective or even counterproductive. When seeking help in Ireland, look for a professional accredited by the PSI or IACP who explicitly lists ERP for OCD as a core specialty. A correct diagnosis from a qualified professional is the first step towards a targeted and effective treatment plan.
Next in this series: What is Exposure and Response Prevention (ERP)? Your Complete Guide
Return to our main guide: Obsessive-Compulsive Disorder (OCD): The Definitive Guide for Ireland