What is Dysautonomia? a Beginners Guide
Written by: Anna Nelson - Clinical Exercise Physiologist
What is dysautonomia? A beginners guide
Dysautonomia is an umbrella term used to describe a range of symptoms, disorders and dysfunction of the autonomic nervous system.
The Autonomic nervous system (ANS)
The autonomic nervous system consists of the sympathetic, parasympathetic, and enteric (gastrointestinal control) systems. It uses networks of nerves to transmit signals from the brain to various parts of the body, constantly maintaining a fine balance between these divisions to keep the body in a stable state of homeostasis. The autonomic nervous system controls the following and more:
Heart rate
Blood pressure
Gastric motility
Gastric secretion
Bladder function
Respiration control
Temperature control
In individuals with dysautonomia, these systems do not regulate appropriately, resulting in a wide range of symptoms that can fluctuate in severity and presentation between individuals.
How Dysautonomia Affects the Body
Autonomic Nervous System Dysfunction
Dysautonomia involves impaired regulation within the ANS. Communication between the sympathetic and parasympathetic systems becomes altered, affecting control of heart rate, blood pressure, vascular tone, digestion, and temperature regulation.
This imbalance can result in either excessive activation or insufficient response of these systems.
Cardiovascular Dysregulation
Autonomic dysfunction can significantly affect cardiovascular control, including:
Abnormal heart rate regulation, with heart rate rising or falling inappropriately
Impaired blood vessel constriction, particularly during posture changes
Reduced venous return, where blood pools in the lower limbs or abdomen, limiting blood flow back to the heart
These mechanisms may contribute to symptoms such as dizziness, palpitations, fatigue, exercise intolerance, and fainting.
Blood Volume and Circulatory Issues
Many individuals with dysautonomia experience abnormalities in circulation, including:
Low blood volume (hypovolemia):
Reduced circulating blood volume can impair the body’s ability to maintain adequate blood pressure and organ perfusion.Venous pooling:
Inadequate constriction of blood vessels allows blood to accumulate in the legs and abdominal region, reducing effective circulation to the heart and brain.
Neuroendocrine and Hormonal Factors
The autonomic nervous system works closely with hormonal control systems. In dysautonomia, this interaction may be disrupted.
Excess sympathetic activation:
Some individuals experience heightened sympathetic activity, leading to elevated stress hormone release such as norepinephrine. This may cause symptoms including palpitations, tremor, sweating, anxiety, and temperature intolerance.Impaired baroreceptor reflex:
Baroreceptors normally detect changes in blood pressure and help regulate heart rate and vascular tone. Reduced sensitivity or delayed responses can impair the body’s ability to stabilise circulation, particularly with position changes.
Respiratory Regulation and Breathing Control
The autonomic nervous system plays a key role in regulating breathing rate, rhythm, and depth. In dysautonomia, this control can become disrupted.
As a result, individuals may experience:
Changes in respiratory rate
Rapid or shallow breathing
Hyperventilation
Sensations of air hunger or difficulty getting a full breath
These breathing changes are often due to altered autonomic and may occur at rest, during stress, with posture changes, or alongside other autonomic symptoms such as palpitations, dizziness, or fatigue.
Breathing pattern dysfunction can further influence heart rate, blood pressure regulation, and symptom severity, contributing to the overall autonomic burden experienced by many individuals with dysautonomia.
Causes of dysautonomia
Dysautonomia can have many possible causes, and in some cases no clear cause is identified. Or it may develop in association with:
Autoimmune diseases (e.g. lupus, Sjögren’s syndrome, coeliac disease)
Connective tissue disorders such as Ehlers–Danlos syndromes
Post-viral illness (including COVID-19 and other viral infections)
Long COVID
Physical trauma or major surgery
Prolonged bed rest or severe deconditioning
Hormonal changes, including pregnancy
Diabetes and other metabolic disorders
Cancer and neurological conditions
Genetic or hereditary factors
Environmental exposures including alcohol or certain metals
Types of dysautonomia
There are around 15 different forms of dysautonomia. However, some of the most common include:
Postural orthostatic tachycardia syndrome (POTS)
Orthostatic hypotension (OH)
Vasovagal syncope
Inappropriate sinus tachycardia (IST)
Autoimmune autonomic ganglionopathy
Familiar dysautonomia
Some patients may have more than one form of dysautonomia and the symptoms may overlap.
Symptoms commonly experienced in dysautonomia
Due to the wide range of functions that the ANS controls, symptoms can affect many different bodily systems including:
Orthostatic intolerance: Dizziness, light-headedness, fainting (syncope).
Cardiovascular: Rapid heart rate (tachycardia), palpitations, low blood pressure, chest pain.
Neurological: Brain fog, headaches/migraines, tremors, blurred vision, sleep problems.
Gastrointestinal: nausea, bloating, constipation, diarrhoea, swallowing difficulties
Thermoregulation: Sweating too much or too little, heat/cold intolerance, clammy skin
Respiratory: Shortness of breath
Urinary: Frequent urination, incontinence, trouble emptying bladder
Symptoms very dramatically with the number of symptoms and intensity varying between individuals.
How to manage dysautonomia – see additional blogs for more information
Based on accumulated evidence and expert consensus, there are a wide range of non-pharmacological and pharmacological management strategies available including:
Adequate fluid and sodium intake
Compression garments
Physical reconditioning and exercise therapy
Lifestyle and postural strategies (counter maneuvers)
Symptom-target medications
The starting point of each individual will vary, and so it is important that you talk to your health care professional about what would be best suited for you.
Key Messages
Dysautonomia is a term for conditions affecting the autonomic nervous system, which controls automatic functions such as heart rate, blood pressure, digestion, and temperature regulation.
It can develop after illness, trauma, pregnancy, or due to underlying medical, autoimmune, genetic, or post-viral conditions like Long COVID, though some people have no clear cause.
There are several types of dysautonomia, symptoms vary widely between individuals, and management is personalised using lifestyle strategies, physical reconditioning, and medications with healthcare guidance.
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