OCD is more common than many people realise. National prevalence estimates for England suggest that a meaningful proportion of the population may experience OCD related difficulties at some point, and research has found that only a minority of those people have ever received a formal professional diagnosis. A guide cannot diagnose OCD or determine whether a pattern of intrusive thoughts and compulsive responses is clinically significant. An assessment can consider the full picture. The gap between prevalence and diagnosis is relevant for people in West London who may have experienced intrusive thoughts, compulsive responses, avoidance or mental rituals for some time without having had a formal assessment. OCD can present in ways that do not match the public image of the condition, and it can be mistaken for depression, generalised anxiety, health anxiety, perfectionism or a personality trait. Shame, secrecy and uncertainty about whether the experience is serious enough can all delay help seeking. NHS service capacity and local commissioning decisions in West London affect how promptly people in Chiswick, Ealing and the Richmond venue can access assessment and evidence based support. Private assessment and therapy can be an option for people who want to discuss their experience without waiting. A guide cannot advise on which route is appropriate for an individual. CBT with exposure and response prevention may be considered after individual assessment where OCD is affecting daily life. Exposure based work should be planned with a suitably qualified clinician after discussion of the rationale, alternatives, safety and pacing. For related information, see OCD therapy at https://lyceumclinic.co.uk/therapy/ocd/, the OCD comprehensive guide at https://lyceumclinic.co.uk/guides/ocd comprehensive guide/, OCD CBT tools at https://lyceumclinic.co.uk/guides/ocd cbt tools today/ and why OCD goes undiagnosed for years at https://lyceumclinic.co.uk/guides/ocd undiagnosed years/. If there is immediate danger, thoughts of self harm, an inability to stay safe or a sudden marked deterioration, call 999, attend A&E or use urgent local crisis or medical support.