Understanding POTS: What do we know?
Intro to POTS
Postural orthostatic tachycardia syndrome (POTS) is the most common type of dysautonomia where the autonomic nervous system does not adjust well to standing. Patients with POTS experience significant impacts on daily activities and quality of life. Although POTS is still not fully understood, learning what happens in the body when standing can help people with POTS recognise their symptoms and manage them more effectively.
What normally happens when you stand?
Normally on standing, approximately 500-700 mLs of blood volume moves into the abdomen and legs because of gravity, leading to less blood returning to the heart and brain. Special sensors located in the neck and near the heart (called baroreceptors) sense a decrease in blood pressure and signal to the autonomic nervous system to respond by increasing the heart rate by ~10-20 beats-per-minute and tightening the blood vessels in the legs. These adjustments help to push blood back towards the heart and restore blood pressure. Once this happens, the heart rate returns to baseline and you're good to go.
What is happening in POTS?
In POTS, these normal adjustments to standing don’t work as effectively as they should. When a person with POTS stands up, more blood than usual moves into the abdomen and legs because of gravity, so less blood returns to the heart and brain. To compensate, the heart beats harder and faster to maintain blood pressure and keep blood flowing to the brain.
Several mechanisms may contribute to this, including:
Blood vessels not tightening well on standing: which reduces blood return back toward the heart.
Low total blood volume (hypovolemia): meaning there isn’t enough circulating blood volume to maintain normal blood return when standing.
Excess sympathetic nervous system activity: sometimes described as an overactive “fight‑or‑flight” response, which can lead to a rapid heart rate and other symptoms.
These mechanisms often overlap and can influence one another. For example, when less blood returns to the heart on standing, the body responds by increasing sympathetic nervous system activity (the “fight‑or‑flight” system) in an effort to maintain blood pressure and keep blood flowing to the brain. This heightened sympathetic response can then drive an even faster heart rate and contribute to many of the symptoms people with POTS experience.
Other factors that may also contribute to POTS include
Changes in breathing pattern,
Problems with how blood flow to the brain is regulated,
Immune system changes,
Inappropriate mast cell activation
Connective tissue disorders like Ehlers‑Danlos syndrome or Hypermobility Spectrum Disorder.
These changes when standing lead to symptoms of orthostatic intolerance such as:
Rapid heart beat
Feeling dizzy or light‑headed
Feeling like you might faint
Shortness of breath or breathing faster than usual
Fatigue, concentration difficulties, or nausea
These symptoms improve when you sit or lie down because blood can flow back to your heart and brain more easily.
Managing POTS
Managing POTS focuses on improving blood flow back to the heart and reducing the heart’s need to work so hard. Helpful strategies often include:
Drinking more water and adding extra salt to increase blood volume.
Wearing compression garments to keep blood from pooling in the legs and abdomen.
Tensing and relaxing your leg muscles when standing to help push blood back towards the heart.
Avoiding heat, since it makes blood vessels relax and can worsen symptoms.
Not lying down for long periods, so your body doesn’t have to readjust when standing.
Exercise can help improve blood volume, circulation, and overall tolerance to standing (see link to blog)
Medications to reduce heart rate and increase blood pressure may be prescribed by your doctor.
These approaches often work best when combined and tailored to each person’s symptoms and lifestyle.
Closing thoughts
POTS is a complex condition with multiple contributing factors, and it affects each person differently. Understanding what’s happening in the body and why it feels the way it does can make the experience less confusing and help people with POTS feel more in control. With this insight, many people with POTS can manage their symptoms better and improve daily functioning.
Check out the other blog posts from Dysautonomia New Zealand for more information on managing symptoms.
References
Arnold, A. C., Ng, J., & Raj, S. R. (2018). Postural tachycardia syndrome–diagnosis, physiology, and prognosis. Autonomic Neuroscience, 215, 3-11. https://doi.org/10.1016/j.autneu.2018.02.005
Fedorowski, A. (2019). Postural orthostatic tachycardia syndrome: clinical presentation, aetiology and management. Journal of internal medicine, 285(4), 352-366. https://doi.org/10.1111/joim.12852
Lau, D. H., Fedorowski, A., Raj, S. R., Schild, C., Pace, L. A., Blitshteyn, S., ... & Gallagher, C. (2026). Postural Orthostatic Tachycardia Syndrome: A State-of-the-Art Review. Heart, Lung and Circulation. https://doi.org/10.1016/j.hlc.2025.09.004
Olufsen, M. S., Ottesen, J. T., Tran, H. T., Ellwein, L. M., Lipsitz, L. A., & Novak, V. (2005). Blood pressure and blood flow variation during postural change from sitting to standing: model development and validation. Journal of Applied Physiology, 99(4), 1523–1537. https://doi.org/10.1152/japplphysiol.00177.2005
Sheldon, R. S., Grubb II, B. P., Olshansky, B., Shen, W., Calkins, H., Brignole, M., Raj, S. R., Krahn, A. D., Morillo, C. A., & Stewart, J. M. (2015a). 2015 heart rhythm society expert consensus statement on the diagnosis and treatment of postural tachycardia syndrome, inappropriate sinus tachycardia, and vasovagal syncope. Heart Rhythm, 12(6), e41–e63. https://doi.org/10.1016/j.hrthm.2015.03.029
Stewart, J. M., & Montgomery, L. D. (2004). Regional blood volume and peripheral blood flow in postural tachycardia syndrome. American Journal of Physiology-Heart and Circulatory Physiology, 287(3), H1319-H1327. https://doi.org/10.1152/ajpheart.00086.2004
