PoTS is a condition which affects the autonomic nervous system, the system responsible for regulating the involuntary processes which take place in the body such as breathing and digestion. When going from a sitting or lying position to standing, the normal response is for blood vessels to contract and the heart rate to increase slightly to ensure that enough blood is getting to the brain. In people with PoTS, this automatic regulation is impaired, and the heart beats much more quickly, resulting in symptoms such as palpitations, dizziness, fainting, headaches (likely due to reduced blood flow to the brain), tiredness, brain fog, shortness of breath and chest pain.

Many patients find that symptoms are worse in the heat, after meals, after alcohol or caffeine, when dehydrated, and, for women, during their menstrual period. Some patients are only troubled in trigger situations such as the heat, but others can have debilitating symptoms which significantly affect their quality of life and ability to function normally.

PoTS is often associated with other conditions such as Joint Hypermobility Syndrome, Ehlers-Danlos syndrome type III and Autonomic Mediated Syncope. These conditions can create a constellation of health problems affecting many systems in the body, with joint dislocations, bladder infections and gastrointestinal upset being commonplace. Patients with PoTS and these associated disorders may need to see a number of specialists in order to manage their symptoms and lead a normal life.