Most people feel a flutter of worry when they notice something odd about their body. But for some people, that worry doesn't go away — it grows, and it starts to take over daily life. This is what researchers call Illness Anxiety Disorder (IAD), sometimes known as health anxiety.
A 2024 review by Kikas and colleagues looked at everything we currently know about IAD — what causes it, how it's diagnosed, and what actually helps. What they found paints a clearer picture of why some people get stuck in cycles of health worry while others don't. Things like past experiences with illness, how we learned to think about our bodies growing up, and even our general anxiety levels all play a role.
This matters because health anxiety isn't just uncomfortable — it can be exhausting. Constantly Googling symptoms, seeking reassurance from doctors, or avoiding anything that reminds you of illness can quietly shrink your world. It can look like physical illness but feel like anxiety, which makes it confusing for both the person experiencing it and the people around them.
The good news? It's very treatable. If health worries are taking up more space in your life than you'd like, talking to a psychologist is a genuinely helpful next step.
The nature of this study
This paper by Kikas et al. is a review, not a new experiment. Rather than testing a treatment directly, the authors gathered existing research on Illness Anxiety Disorder (IAD) and assessed where the field currently stands: what is known about its causes, its diagnostic status, its clinical features, and how it is assessed and treated in children and adults. A review of this kind differs from a randomised controlled trial (RCT), where a treatment is tested directly against a comparison condition. Instead, it draws together many separate studies to look for agreement, disagreement, and gaps that still need attention.
Where does IAD belong?
One question the review examines closely is diagnostic classification. IAD currently sits within the anxiety disorders, but there is ongoing debate about whether this is the right category, given its overlap with Somatic Symptom Disorder (SSD). SSD involves distressing physical symptoms accompanied by excessive thoughts, feelings, or behaviours about those symptoms. IAD is different in emphasis: it centres on fear of having or developing a serious illness, often regardless of whether physical symptoms are present or severe. The review concludes that this boundary is not yet settled, and points to a specific reason why. Much of the existing research has not applied the DSM-5 criteria for IAD consistently. Without a shared set of criteria across studies, comparing results becomes difficult, and a clear picture of the disorder is harder to build.
What the evidence supports
The review is more confident on treatment. Cognitive Behavioural Therapy (CBT), a structured therapy that helps people identify and change unhelpful thought patterns and behaviours, is identified as an effective approach for IAD. The authors also note that several validated measures of health anxiety already exist. These give psychologists reliable tools to assess the severity of a person's health anxiety and to track whether it changes over the course of treatment. Taken together, this is a useful position for the field to be in: a condition that responds to treatment, and instruments that allow clinicians to measure progress with some confidence, even while broader questions about diagnosis remain unresolved.
The limits of current knowledge
The review is direct about where evidence is thin. Research on health anxiety in children and adolescents is described as limited, which means much of what clinicians currently rely on comes from studies of adults. How IAD presents in younger people, and how best to treat it at that age, remains less clear. The authors also emphasise that IAD tends to be chronic and disabling when left unaddressed, which adds weight to their call for further research using proper DSM-5 criteria. Without that, questions about classification, particularly in young people, are unlikely to be resolved.
What this review offers, then, is not a new finding so much as an honest stocktake. Some things are reasonably well established: CBT helps, and workable assessment tools exist. Other things remain genuinely open, including how IAD should be classified and how it looks in children. That combination of clarity and acknowledged uncertainty is worth taking seriously rather than treating as a weakness of the field.
If you recognise this kind of health anxiety in yourself, or in someone you are caring for, it is worth remembering that effective treatment exists and that a psychologist can help assess what is happening and what might help. Reaching out is a reasonable step, and support is available.