Pure O: what the term means and how OCD with mainly mental compulsions is treated

The term is short for "purely obsessional" OCD. It became popular online to describe people whose main experience is distressing intrusive thoughts, images or urges, without the visible rituals such as handwashing or repeated checking that most people associate with OCD.

OCD-UK explains that the label is commonly used for a form of OCD that people mistakenly believe has no outward compulsions. It says that as an online term it exists, but as a form of OCD it does not really, and it is not a medically listed term. The charity avoids using it because it can be misleading and can stop people recognising their own compulsions.

None of this makes the experience any less real or distressing. What the clinical view says is that the compulsions are present but are happening in the mind or in subtle behaviours that are easy to overlook.

The NHS describes OCD as having 3 main elements: obsessions (unwanted, intrusive and often distressing thoughts, images or urges that repeatedly enter the mind), emotions (intense anxiety or distress caused by the obsession) and compulsions (repetitive behaviours or mental acts that a person feels driven to perform as a result). The compulsion temporarily relieves the anxiety, but the obsession and anxiety soon return and the cycle begins again.

The NHS includes mental acts in its description of compulsions and lists examples such as repeating words in the head and thinking "neutralising" thoughts to counter the obsessive thoughts. It also lists asking for reassurance and avoiding places and situations that could trigger obsessive thoughts. These are exactly the behaviours that tend to hide inside what is called Pure O.

The NHS states that not all compulsive behaviours will be obvious to other people. OCD-UK gives examples of subtler compulsions: checking (from checking online to checking your own body reactions or sensations), seeking reassurance from loved ones and avoiding particular objects, places or people.

The NHS gives examples of common obsessions: fear of deliberately harming yourself or others (for example, fear you may attack someone, such as your children), fear of harming yourself or others by mistake (for example, setting the house on fire by leaving the cooker on), fear of contamination, and a need for symmetry or orderliness. It adds that thoughts may be of a violent or sexual nature that the person finds repulsive or frightening.

The NHS is clear that these are just thoughts, and having them does not mean you will act on them. They are classed as OCD if they cause distress or have an impact on quality of life. Almost everyone has unpleasant or unwanted thoughts at some point; what differs in OCD is that the thought dominates and cannot be shaken.

• Harm obsessions, such as fear of hurting someone you love.

• Unwanted sexual thoughts or images that feel out of character.

• Fear of contamination or illness.

• Needing things to feel "just right" or symmetrical.

The NHS says it is important to get help if you think you have OCD and it is having a significant impact on your life, and that OCD is unlikely to get better on its own. There are 2 main ways to get help: refer yourself directly to an NHS talking therapies service, or see a GP, who can prescribe a suitable medicine or refer you to a local talking therapies service.

If you ever feel you cannot go on, the NHS says to contact a GP or care team immediately. You can also call the Samaritans on 116 123 or contact NHS 111. The NHS adds that people with OCD may also have or develop depression, an eating disorder, generalised anxiety disorder or a hoarding disorder, and that people with OCD and severe depression may have suicidal feelings. In an emergency, call 999 or go to A&E.

People with intrusive thoughts about harm often worry that they are dangerous. It can be helpful to describe these worries to a GP or therapist exactly as they are, so that they can be recognised as a feature of OCD.

The NHS says OCD can be treated, and that the 2 main treatments are talking therapy and medicine. A short course of therapy is usually recommended for relatively mild OCD, and more severe OCD may need a longer course of combined therapy and medicine. It notes that it can take several months before you notice the benefit.

OCD-UK says there is no need for a "Pure O" specialist, because the condition is treated using the same standard methods as every other type of OCD.

In ERP the aim, as the NHS puts it, is to face your fears and have obsessive thoughts without neutralising them with compulsive behaviours. This can feel counter-intuitive, which is one reason the NHS describes the treatment as hard work, while saying that many people find the anxiety eventually improves or goes away when they confront their obsessions.

The NHS says support groups can provide reassurance and coping advice, reduce feelings of isolation and offer information for family members. It names OCD Action, OCD-UK and TOP UK as national charities that can provide information about groups in your area. It also points to the Maternal OCD website for mothers with OCD, and notes that SSRIs can be prescribed in pregnancy if the GP thinks the benefits outweigh the risks.