Often more simply referred to as postural tachycardia syndrome, or POTS, this disorder is characterized by the body's inability to make the necessary adjustments to counteract gravity when standing up.

It is a condition of dysautonomia,[1] more specifically orthostatic intolerance, in which a change from the supine position to an upright position causes an abnormally large increase in heart rate, called tachycardia. Several studies show a decrease in cerebral blood flow with systolic and diastolic cerebral blood flow (CBF) velocity decreased 44% and 60%, respectively.[2] Patients with POTS have problems maintaining homeostasis when changing position, i.e. moving from one chair to another or reaching above their heads. Many patients also experience symptoms when stationary or even while lying down.

The defining symptom of POTS is an excessive heart rate increment upon standing. However, as you will discover, there are a multitude of other symptoms that often accompany this syndrome. As such, POTS can be a difficult disorder to detect and understand.

Postural Orthostatic Tachycardia is a syndrome. As such, there is a collection of symptoms that distinguish it. The symptoms are widespread because the autonomic nervous system plays an extensive role in regulating functions throughout the body. Many of these symptoms, such as low blood pressure,* may present only after prolonged standing. Symptoms will vary from person to person. The following is a list of symptoms reported by patients. When possible, we have included the percentage of patients that research reports have experienced a given symptom.

Symptoms presumed to be related to cerebral hypoperfusion:**
  • Lightheadedness  77.6 % (Grubb, 2000)
  • Fainting or near fainting 60.5% of patients report near fainting (Grubb, 2000)
  • Generalized weakness 50% (Low et al.)
Symptoms presumed to be related to autonomic overactivity include the following:**
  • Palpitations 75% (Grubb, 2000)
  • Tremulousness 37.5% (Low, Opffer-Gehrking, Textor, Benarroch, Shen, Schondorf, Suarez & Rummans, 1995)
  • Shortness of breath 27.6 % (Grubb, 2000)
  • Chest discomfort and/or pain 24.3 % (Grubb, 2000)
Sudomotor symptoms include the following:**
  • Loss of sweating 5.3 % (Low et al.)
  • Excessive sweating 9.2 % (Robertson, 2000)
    Loss of sweating and excessive sweating are more common in patients with elevated norepinephrine levels (Thieben, Sandroni, Sletten, Benrud-Larson, Fealey, Vernino, Lennon, Shen & Low, 2007).
Symptoms that may reflect dysautonomia:**
  • Delayed gastric emptying 23.7% of patients report gastrointestinal complaints, including bloating (Grubb et al., 1997)
  • Bloating after meals (Grubb et al., 1997)
  • Nausea 38.8% (Robertson, 2000)
  • Vomiting 8.6% (Thieben et al., 2007)
  • Abdominal pain  15.1% (Thieben et al., 2007)
  • Diarrhea 17.8% (Jacob & Biaggioni, 1999) (sometimes with alternating constipation)
  • Constipation 15.1% (Thieben et al., 2007)
  • Bladder dysfunction 9.2% (Thieben et al., 2007) (this may include Polyuria (Jacob & Biaggioni, 1999) (excessive urination)
  • Pupillary dysfunction 3.3% (Thieben et al., 2007) Pupillary dysfunction may or may not be responsible for some other reported symptoms, such as: Blurred Vision (Grubb, 2000) and Tunnel vision (Low et al.).
Generalized Complaint symptoms:**
  • Fatigue 48% (Grubb, 2000) (which can be disabling) 
  • Sleep disorders 31.6% (Low et al.) (can cause unrefreshing sleep and an increased need for sleep)
  • Headache/migraine 27.6% (Grubb, 2000)
  • Myofascial pain 15.8% (Thieben et al., 2007) (characterized by regional muscle pain accompanied by trigger points)
  • Neuropathic pain 3% (Thieben et al., 2007)
Other symptoms reported in research that are not categorized above include:
  • Dizziness (Grubb, 2000)
  • Tachycardia (Grubb, 2000)
  • Exercise intolerance (Grubb, 2000)
  • Clamminess (Grubb, 2000)
  • Anxiety (Grubb, 2000)
  • Flushing (Grubb, 2000)
  • Postprandial hypotension (Grubb, 2000) (low blood pressure after meals) 
  • Blood pooling in limbs (Grubb, 2000) (can make legs feel heavy and appear mottled and purple in color) 
  • Intolerance to heat (Grubb & Karas, 1999)
  • Feeling cold all over (Grubb & Karas, 1999)
  • Low blood pressure upon standing (Grubb, Kosinski, Boehm & Kip, 1997) (Some physicians feel orthostatic hypotension is a separate entity from POTS)
  • Cognitive impairment (Grubb et al., 1997) (may include difficulties with concentration, brain fog, memory and/or word recall)
  • Narrowing of upright pulse pressure (Jacob & Biaggioni, 1999)
  • Cold hands (Low et al.) (and often feet & nose)
  • Hypovolemia (Low et al.) (low blood volume)
  • Chills (Low et al.)
  • High blood pressure (Low et al.)
  • Hyperventilation (Low et al.)
  • Numbness or tingling sensations (Low et al.)
  • Reduced pulse pressure upon standing (Low et al.)
  • Low back pain (Mathias, 2000)
  • Aching neck and shoulders (Mathias, 2000)
  • Noise sensitivity (Stewart, 2001)
  • Light Sensitivity (Stewart, 2001)
  • Disequalibrium (Sandroni, Opfer-Gehrking, McPhee & Low, 1999)
The above are symptoms reported by POTS researchers. Other symptoms sometimes reported by POTS patients include:
  • Arrhythmias (irregular heart beats)
  • Chemical sensitivities (May have multiple chemical sensitivity and can be very sensitive to medications - may only need small doses)
  • Easily over-stimulated 
  • Feeling full quickly
  • Feeling "wired"
  • Food allergies/sensitivities (some foods seem to make symptoms worse)
  • Hyperreflexia
  • Irregular menstrual cycles
  • Loss of appetite
  • Loss of sex drive
  • Muscle aches and/or joint pains
  • Swollen nodules/lymph nodes
  • Polydipsia (excessive thirst)
  • Weight loss or gain
  • Feeling detached from surroundings
  • Restless leg syndrome
POTS symptoms can vary from day to day. They tend to multiply and become exaggerated upon upright posture. Blood flow and blood pressure regulation are also abnormal while supine or sitting, but these abnormalities may not be as apparent and may require orthostatic stress to become evident (Stewart & Erickson, 2002).

Some patients do report symptoms occurring while sitting or lying down. Heat, exercise and eating can exacerbate symptoms. Women sometimes report an increase in symptoms around menstruation.

 Not all patients will experience a drop in blood pressure upon standing. Some physicians define orthostatic hypotension as a separate entity from POTS.