OCD obsessions are characterised by anxiety driven urges or images that arise repeatedly, uninvited and persistently. In many cases, people carry out an obsession in order to rid themselves of a compulsion. Personally, I find that these obsessions appear when you are trying to concentrate on a specific task. These obsessions are usually categorised, due to their effect on the sufferer and the people around them. Some of these categories include:

- Organisation and symmetry

- Aggressive thoughts about causing harm to themselves or others

- Fear of cleanliness or filth

Obsessions in great detail

Obsessions are individual to each sufferer and is a very private experience. Many people, such as myself, may not even recognise that what they do on a daily basis is an obsession and more of a habit. But obsessions can be categorised further into the following:

Contamination fears

One of the most prevalent and common obsessions among people who suffer from OCD. This obsession usually stems from a fear of some kind of disease or illness (most commonly, death but can sometimes be blindness or religious plagues). Clearly there are some dangers in the everyday world that do indeed have an effect on one's health (such as asbestos) which many people are aware of but do not think about on a daily basis. However, a person who suffers from OCD with a contamination obsession would think that rain water has washed asbestos into the streets and there are now asbestos particles in the atmosphere, and so they would be afraid to leave the house when raining. Depending on where the contamination obsession resides on an OCD's sufferer's hierarchy of severity depends on how extreme the obsession is itself and the person's reaction to the obsession. Often, this obsession manifests due to a fear of an illness or disease, so one feels responsible for the protection of their loves ones against disease. This is illustrated through thorough and frequent hand washing (in the person's behaviour and their attempts to get others to follow), constant cleaning of surfaces and becoming triggered into a frenzy by small stains and the quality of the air. One's goal when they have a contamination obsession is to create a 'safe space' where both them and the people they care about are out of the way of any kind of contamination risk, this includes: air pollutants, grease, dirt and germs, household items, environmental contaminants, bodily fluids and secretion of wastes, sticky substances, and animals and insects.

Causing harm 

This includes the fear of harming either oneself or other people around them. People with OCD feel responsible for their actions, whether they are or not, including for those that are outside their control. This means that they may doubt whether they have carried out an important task correctly or be unsure whether they have done it all; therefore, sufferers with this obsession tend to carry out repetitive, continuous checking. People who often doubt themselves are often thought of having a fear of harming people in general, whether that be themselves or others around them. People who experience this as their primary obsession experience intrusive thoughts, impulses, images and fears of harming either themselves or people around them due to their own negligence. Alongside these, sufferers experience intense feelings of fear, doubt and uncertainty. 

Sexual obsessions

Sexual OCD is a commonly misunderstood subtype of OCD; OCD is categorised into 4 major OCD dimensions: contamination, doubt/harm, symmetry/arranging and unacceptable/taboo thoughts - this is also known as 'pure obsession' or 'pure-o' for short. Within the pure-o category lies sexual obsessions, which are unwanted sexual thoughts - these can involve children, family members, animals and even religious figures/deities. These may involve same-sex relations or a fear of changing sexual orientation. When conceptualising sexual obsessions, it is important to recognise that OCD individuals see these as immoral and do not wish to act them out; these are different from fantasies, which nearly every person experiences at some point, which are pleasurable whereas obsessions invoke guilt and a sense of shame. 

Obsessions within OCD can take a number of different forms, including sexual orientation obsessions. In some cases, this includes unwanted same-sex activity, intrusive images and fears relating to one's sexual orientation. Obsessions about sexual orientation are different to people who actually identify as LGBTQ+, as they may think about same-sex activities but this is unwanted and seems immoral - whereas people who identify as LGBTQ+ find these thoughts pleasurable and desire same-sex relationships and/or activity. An individual who suffers from sexual orientation obsessions fear becoming gay or discovering that they may have been gay their entire life. This is by no mean homophobic on their behalf, this is not voluntary and not based on their own opinions.