Fear of Illness and Health Anxiety: How Anxiety, Reassurance-Seeking, and Stress Can Make Us Feel Sicker

Fear of illness is a deeply human experience. Our brains are wired to protect us, and concern about our health is often an adaptive signal to rest, seek care, or slow down. However, when fear becomes persistent and overwhelming, it can evolve into health anxiety (also called illness anxiety), creating a paradoxical effect: the more we fear getting sick, the more unwell we may feel.

Research shows that chronic anxiety about health activates stress pathways in the body, heightens physical sensations, and keeps the nervous system in a state of threat. Over time, this cycle can intensify anxiety-related physical symptoms and make the body feel less resilient rather than more protected.

Fear of Illness and the Stress–Body Loop

When fear of illness is present, the brain interprets bodily sensations as potential danger. This activates the sympathetic nervous system and the hypothalamic pituitary adrenal (HPA) axis, leading to the release of stress hormones such as cortisol and adrenaline (Segerstrom & Miller, 2004).

While this stress response can be helpful in short bursts, chronic activation has significant physiological costs, including immune dysregulation, increased inflammation, sleep disruption, and slower recovery from illness (Slavich & Irwin, 2014). This stress loop helps explain why many people report that anxiety makes them feel sick, even when medical evaluations are reassuring.

Health Anxiety and Nervous System Sensitization

Individuals with health anxiety tend to have heightened interoceptive awareness, an increased sensitivity to internal bodily sensations such as heart rate, digestion, pain, or fatigue (Paulus & Stein, 2010; Owens et al., 2021).

This creates a reinforcing cycle that can look like:

1. Normal bodily sensation

2. Catastrophic interpretation of sensation (“Something is wrong”)

3. Increased anxiety

4. Heightened physiological arousal

5. Intensified physical symptoms

Over time, this process leads to nervous system sensitization, where the body becomes more reactive and less able to return to baseline.

The Brain’s Desire for Control

Fear of illness reflects the nervous system’s attempt to regain control and predictability. When someone has experienced past illness, medical trauma, chronic stress, or emotional trauma, the brain learns that uncertainty is unsafe. As a result, it increases vigilance toward the body as a survival strategy (Porges, 2011).

In this state, normal human experiences such as fatigue, aches, digestive changes, or brief illness are perceived as threats rather than expected fluctuations of being embodied. A mind–body approach recognizes that experiencing illness is a normal part of life, not evidence that the body is broken. Healing involves helping the nervous system learn that it can remain regulated even when discomfort or uncertainty is present, rather than trying to eliminate all risk (Mehling et al., 2018).

Reassurance-Seeking Perpetuates Health Anxiety

One of the most common behaviors associated with health anxiety is reassurance-seeking. This may include repeated doctor visits, frequent symptom checking, searching the internet for diagnoses, or asking loved ones for reassurance.

Although reassurance provides temporary relief, research consistently shows that it maintains health anxiety over time. Reassurance-seeking functions as a safety behavior, it reduces anxiety briefly but reinforces the belief that uncertainty is dangerous and intolerable, making symptoms worse over time (Salkovskis & Warwick, 2003).

Recent studies demonstrate that reassurance-seeking mediates the relationship between anxiety and illness preoccupation, meaning it actively sustains fear rather than resolving it (Norbye et al., 2022; Kim et al., 2022). Reassurance interrupts the nervous system’s ability to learn, “I can survive this sensation without external rescue.”

Stress, Anxiety, and the Immune System

Chronic anxiety does not stay confined to the mind. Psychological stress is associated with increased inflammatory processes and altered immune functioning, which can worsen symptom severity and prolong recovery from illness (Dantzer et al., 2008; Slavich & Irwin, 2014).

This helps explain why individuals with health anxiety often feel run down, depleted, or “on the verge of getting sick.” The symptoms are real, even when their origin is functional rather than structural, driven by nervous system dysregulation rather than disease.

Moving Toward Safety Instead of Surveillance

Effective treatment for health anxiety focuses on restoring nervous system safety, not increasing bodily surveillance. Evidence-based and trauma-informed approaches often include:

• Reducing reassurance-seeking and checking behaviors

• Increasing tolerance of uncertainty

• Supporting nervous system regulation

• Rebuilding trust in bodily sensations

Cognitive-behavioral therapy, acceptance-based approaches, and somatic therapies all support this process when applied through a compassionate, mind–body framework (Owens et al., 2021; Mehling et al., 2018).

A Gentle Reframe

Your body is not fragile.

Your sensations are not imagined.

And fear of illness does not keep you safe.

Learning to regulate the nervous system, rather than control every sensation, is often what allows true resilience and well-being to return.

If fear of illness, health anxiety, or persistent anxiety-related physical symptoms are impacting your life, working with a trauma-informed, mind–body therapist can help restore a sense of safety and trust in your body. Her at Well Mind Body our team works with people who experience health anxiety every day. If you are struggling, please know we are here to help.

Thanks for being here,

Dr. E

References

Dantzer, R., O’Connor, J. C., Freund, G. G., Johnson, R. W., & Kelley, K. W. (2008). From inflammation to sickness and depression: When the immune system subjugates the brain. Nature Reviews Neuroscience, 9(1), 46–56. https://doi.org/10.1038/nrn2297

Kim, H. S., Sherman, D. K., & Taylor, S. E. (2022). Reassurance-seeking and health anxiety during infectious disease threat. Frontiers in Psychiatry, 13, 899266. https://doi.org/10.3389/fpsyt.2022.899266

Mehling, W. E., Acree, M., Stewart, A., Silas, J., & Jones, A. (2018). The multidimensional assessment of interoceptive awareness and its relationship to emotional regulation. PLoS ONE, 13(12), e0208034. https://doi.org/10.1371/journal.pone.0208034

Norbye, A. D., Karterud, H. N., & Melin, K. H. (2022). Health anxiety and increased healthcare use: The role of reassurance-seeking behavior. BMC Health Services Research, 22, 195. https://doi.org/10.1186/s12913-022-07529-x

Owens, A. P., Allen, M., Ondobaka, S., Friston, K. J., & Hohwy, J. (2021). Interoceptive inference and health anxiety: A systematic review. Journal of Anxiety Disorders, 78, 102359. https://doi.org/10.1016/j.janxdis.2021.102359

Paulus, M. P., & Stein, M. B. (2010). Interoception in anxiety and depression. Brain Structure and Function, 214(5–6), 451–463. https://doi.org/10.1007/s00429-010-0258-9

Porges, S. W. (2011). The polyvagal theory: Neurophysiological foundations of emotions, attachment, communication, and self-regulation. W. W. Norton & Company.

Segerstrom, S. C., & Miller, G. E. (2004). Psychological stress and the human immune system: A meta-analytic study of 30 years of inquiry. Psychological Bulletin, 130(4), 601–630. https://doi.org/10.1037/0033-2909.130.4.601

Slavich, G. M., & Irwin, M. R. (2014). From stress to inflammation and major depressive disorder. Psychological Bulletin, 140(3), 774–815. https://doi.org/10.1037/a0035302