Health anxiety can present in different ways. Some people are primarily worried about having a serious illness despite medical reassurance. Others experience distressing physical symptoms and find that worry, checking or avoidance has become a significant part of how they manage them. Others notice a pattern of health worry that comes and goes with stress, without meeting the threshold for a clinical diagnosis. A guide cannot diagnose health anxiety, illness anxiety disorder, somatic symptom disorder or any other condition. Physical symptoms can have many possible explanations, including medical conditions, medication, sleep disruption, stress, neurodivergence and other factors. New, severe, persistent or changing physical symptoms should be discussed with an appropriate medical professional. A psychological explanation and a medical question can both need attention at the same time. Clinical frameworks describe different patterns of health anxiety. Illness anxiety disorder, as described in DSM 5, involves persistent preoccupation with having or acquiring a serious illness, often with minimal or no physical symptoms. Somatic symptom disorder involves one or more distressing physical symptoms accompanied by excessive thoughts, feelings or behaviours related to those symptoms. These are clinical categories used by qualified clinicians after assessment. They are not self diagnostic tools. Both patterns can be associated with reassurance seeking, checking, avoidance of medical appointments or the opposite, repeated consultations without lasting reassurance. Both can affect daily life, work and relationships. Both can overlap with depression, generalised anxiety, OCD and other difficulties. An assessment can consider the full picture rather than applying a single label. CBT is one evidence based approach that may be considered after individual assessment for health anxiety. It can involve exploring the links between a health related thought, a bodily sensation, an emotion, a safety behaviour and the short and longer term effect. Any work on checking, reassurance, attention or uncertainty should not involve delaying or avoiding necessary medical care, and should not be copied from a guide. For related information, see health anxiety therapy at https://lyceumclinic.co.uk/therapy/health anxiety/, the health anxiety guide at https://lyceumclinic.co.uk/guides/health anxiety/, health anxiety and relationships at https://lyceumclinic.co.uk/guides/health anxiety relationships/ and body checking and health anxiety at https://lyceumclinic.co.uk/guides/health anxiety body checking/. If there is immediate danger, thoughts of self harm, an inability to stay safe or an urgent medical concern, call 999, attend A&E or use urgent local crisis or medical support.