Contamination in OCD

While there are various forms of Obsessive Compulsive Disorder (OCD), this article will focus on one category known as contamination OCD, and the similarities and distinct differences between its two subcategories – contact contamination OCD and mental contamination OCD.

What is contact contamination OCD?

Individuals who develop contact contamination OCD, typically experience an overwhelming feeling of distress, discomfort or a sensation of uncleanliness, when they come into physical contact with substances, objects, people or animals, that are viewed as ‘contaminants’ (usually containing germs, dirt, disease, bodily waste, secretions, or toxic chemicals). These individuals can have an underlying fear that contact with the contaminant may cause illness or death to themselves or others, or simply be so unpleasant “they will not cope”. Importantly, these fears are highly disproportionate to realistic probabilities and expectations. The contaminants may be real (physical), or ‘magical’ (surreal) – for example fear of contracting illnesses, fatal impairments, health risks, or bad luck, via contact with the names or images of illnesses, people with illnesses, disabled people, or contact with unlucky numbers, superstitious objects, or situations. In an attempt to neutralise their intrusive thoughts and uncomfortable bodily sensations (obsessions) after contact with the contaminant, excessive cleaning rituals (compulsions) of the areas are usually employed until the person feel “de-contaminated”. Avoidance and reassurance seeking around this topic is also common.

Woman wearing mask in city.

What are the common fears and avoidance behaviours involved in contact contamination OCD?

  • HIV, AIDS, STI’s
  • Fear of using public amenities, laundromats, transport, or telephones for fear of contracting germs from others
  • Fear and avoidance of eating out or eating food prepared by others, or using the cutlery or cooking utensils of others for fear of contracting food poisoning or germs
  • Avoiding public spaces involving large crowds of people for fear of increased risk of germs
  • Fear of hospitals, doctors surgeries, or other areas that are associated with illness or blood
  • Fear of tooth decay/ mouth disease developing after eating particular foods- resulting in excessive tooth-brushing
  • Excessive cleaning of kitchen or bathroom for fear of bacteria spreading to themselves or others
  • Fear of shaking hands or coming into close contact with others (eg: hugging or kissing)
  • Fear of being contaminated in a ‘magical’ way via contact with the names of illnesses, disabled people, pictures, or names of people perceived as having serious injuries, diseases, or fatal illnesses
  • Fear of ‘catching’ bad luck from contact with unlucky numbers or objects associated with negative events


What is mental contamination OCD?

Mental contamination OCD shares some similar characteristics to contact contamination OCD in that the compulsive behaviours involved in each, are associated with strong emotions of anxiety and guilt, that invoke intense urges to wash and engage in excessive cleaning rituals in order to soothe and alleviate their distressing thoughts and psychological feelings of ‘dirtiness’. However, the main difference between the intrusive thoughts associated with mental contamination OCD and contact contamination OCD, is that individuals report feeling “mentally polluted” (usually associated with feeling violated or disgusted in some way), as opposed to feeling contaminated by physical contact with external objects or substances. Another distinct difference between the two sub categories, is that individuals’ sensations of dirtiness are experienced as an overall internal discomfort, rather than the localized discomfort and dirtiness experienced as a result of the contaminant coming into physical contact with a particular area of their (eg: contaminated hands after touching a ‘germy’ doorknob).


The intrusive thoughts associated with mental contamination can result from internally conceptualising a past negative memory, image, or perception of an event, typically involving immoral acts and human interaction (eg: from being mistreated in the past – involving instances of abusive language, criticism or betrayal, physical or sexual abuse, or self- harm), or when the subject imagines a scenario perceived to be associated with physical ‘dirtiness’ or disgust (eg: imagining coming into contact with harmful contaminants, or imagining a scenario involving immoral behaviour and violations). These internalised memories or perceptions of past events, including imagined or ‘magical’ scenarios, are often laced with feelings of personal responsibility involving negative appraisals – whereby invoking high levels of shame, guilt, embarrassment, and anger. Unlike contact contamination, mental contamination may not require a visual trigger– this can make it difficult for the individual who experiences the distressing thoughts and compulsions to pin point the cause, for it may be on a subconscious level.  Individuals with mental contamination OCD may also experience the mental thought process called ‘Thought Action Fusion’ (TAF). TAC is identified when individuals experience an irrational and negative thought, with the belief that having the thought alone, will lead to a specific negative action, or the actual reality of that thought (eg: their thought is real or will soon become real simply because they are having the thought).


young man brushing teeth - Contamination OCD: Contact contamination OCD vs Mental Contamination


What are the symptoms of mental contamination?

  • Having
  • Fearing and/or avoiding images or sounds that may provoke the memory of the person or interaction or situation
  • Fearing /avoiding particular words or phrases or places that may trigger the memory or association of the situation that caused them mental harm
  • Unable to say what contaminant they are afraid of just that they “feel disgusted”
  • Increased ‘Thought Action Fusion’ – meaning “If I think of a certain thought I may pollute myself”
  • Attributing high levels of personal responsibility for the memory or imagined scenario associated with dirt or disgust – thereby invoking feelings of shame, embarrassment, guilt, and/ or anger

Painful portrait

How is mental and contact contamination OCD treated?

Both subsets of contamination OCD can be effectively treated with commitment to ongoing cognitive behavioural therapy (CBT) sessions with the guidance and support of a specialising therapist. This typically involves initial low exposure to the contaminant that gradually increases over a period of time as the perceived distress and threat decreases. Mindfulness based CBT is another approach helpful for treating contamination OCD, whereby individuals learn to acknowledge their thoughts as they come and go, and to accept them as ‘just thoughts’ without judging them as either ‘good’ or ‘bad’, or attaching meaning or action to them. There are also various medication options that may be beneficial for some individuals when used in conjunction with therapy.



Our recommended therapist for contamination OCD at Anxiety House


Dr Emily O’Leary – Clinical PsychologistEMILY-5159-1


What is your experience?

  • Clinical Director of Anxiety House and OCD Clinic since 2010
  • Ten years’ experience with clients with OCD and anxiety
  • Clinical supervisor and STAP trained
  • Worked in public and private sectors for many years
  • Worked in acute inpatient and outpatients units
  • Regular speaker on radio and social media
  • Researcher and presenter at international conferences




Sophie Lucas is our Anxiety House blogger and is studying Bachelor of Communications at UQ. Sophie is passionate about anxiety recovery and loves to write about research and provide EDUCATION about anxiety. Sophie and Director Dr Emily O’Leary carefully think about each topic and try and provide the most up to date information. We have a number of scheduled blogs coming up, but we really want to hear your IDEAS! What topics would YOU like to know more about?

If you have any comments or queries feel free to contact us at



Mental contamination in obsessive-compulsive disorder


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