POTS and Related Conditions: Understanding the Body Beyond the Symptoms
What is POTS?
POTS stands for Postural Orthostatic Tachycardia Syndrome. It is a condition that affects how the body regulates heart rate and circulation when moving into an upright position.
Normally, your autonomic nervous system helps keep blood circulating to your heart and brain when you stand up. With POTS, this response does not work as it should, and your heart rate increases more than expected.
Common symptoms include:
A racing or pounding heartbeat when standing.
Dizziness, light-headedness or feeling faint.
Fatigue, weakness and shakiness.
Brain fog or difficulty concentrating.
Headaches, nausea and reduced exercise tolerance.
Digestive symptoms such as bloating, constipation or diarrhoea.
The exact cause of POTS is not fully understood. It can develop after an infection, including COVID-19, and may also occur following surgery, injury or hormonal changes. It is more common in adolescent and adult females.
POTS is assessed by a medical professional using a person's symptoms, heart rate and blood pressure measurements, and investigations to check for other possible causes.
Australian source: Healthdirect Australia — POTS
Why do people talk about POTS alongside other conditions?
POTS is sometimes discussed alongside conditions affecting connective tissue, nerves, blood vessels, digestion, immune responses and energy levels.
Some of these conditions may occur in the same person, while others can cause symptoms that look similar. Researchers are still investigating many of these relationships.
It is important to remember that having one condition does not automatically mean you have another. Symptoms such as fatigue, dizziness, pain and digestive changes can have many different causes.
Below is a simple introduction to the conditions often discussed in this context.
1. Ehlers-Danlos Syndrome (EDS)
What is it?
Ehlers-Danlos syndromes are a group of genetic connective tissue conditions. Connective tissue helps support and hold together structures throughout the body, including joints, skin and blood vessel walls.
Common signs and symptoms:
Flexible or hypermobile joints.
Joints that feel unstable or dislocate easily.
Stretchy or fragile skin and easy bruising.
Ongoing joint or muscle pain.
Fatigue, headaches or digestive problems.
What causes it?
Most types of EDS have a genetic cause. Symptoms vary depending on the type.
How does it relate to POTS?
POTS is recognised as a condition that may occur alongside EDS, particularly hypermobile EDS. However, not everyone with EDS develops POTS, and joint hypermobility alone does not establish an EDS diagnosis.
Australian source: Healthdirect — Ehlers-Danlos syndrome
2. Craniocervical Instability (CCI)
What is it?
Craniocervical instability refers to abnormal movement or instability at the junction where the skull meets the upper spine. This area supports the head and protects important neurological structures.
Possible symptoms include:
Neck pain or difficulty supporting the head.
Headaches, sometimes aggravated by neck movement.
Dizziness or balance difficulties.
In some cases, neurological symptoms such as weakness, altered sensation or swallowing difficulties.
What causes it?
It may be associated with structural problems, injury or certain connective tissue disorders. Symptoms alone cannot establish that instability is present; clinical assessment and appropriate imaging may be needed.
How does it relate to POTS?
CCI is discussed in some EDS and dysautonomia communities because symptoms can overlap. However, the presence of POTS, neck pain or hypermobility does not prove CCI, and the relationship requires careful medical assessment.
Australian source: Ehlers-Danlos Australia — Craniocervical instability
Note: This is a patient-advocacy resource rather than a government clinical guideline. Diagnostic claims about CCI should be checked with an appropriately qualified specialist.
3. Thoracic Outlet Syndrome (TOS)
What is it?
Thoracic outlet syndrome occurs when nerves or blood vessels are compressed in the space between the neck and upper chest, near the collarbone.
Common symptoms include:
Pain in the neck, shoulder, arm or hand.
Pins and needles, numbness or weakness.
An arm that tires easily.
Swelling, coldness or colour changes in the affected arm, particularly when blood vessels are involved.
What causes it?
Possible contributors include anatomical differences, injury, repetitive arm movements or other factors that place pressure on nerves or blood vessels.
How does it relate to POTS?
TOS and POTS affect different body systems. Some symptoms may overlap, but TOS is not an established explanation for POTS in every person who experiences arm pain, tingling or circulation symptoms.
Source: NHS — Thoracic outlet syndrome
4. Mast Cell Activation Syndrome (MCAS)
What is it?
Mast cells are immune cells that help the body respond to allergens and other triggers. Mast cell activation syndrome involves episodes of symptoms caused by the release of chemical mediators from these cells.
Possible symptoms include:
Flushing, itching or hives.
Abdominal pain, nausea or diarrhoea.
Episodes of low blood pressure or feeling faint.
Symptoms affecting several body systems during the same episode.
What causes it?
MCAS describes a group of conditions involving inappropriate mast cell activation. A diagnosis requires a proper clinical assessment and evidence meeting accepted diagnostic criteria; a collection of unexplained symptoms alone is not enough.
How does it relate to POTS?
Some symptoms associated with MCAS and POTS can overlap, including flushing, light-headedness and digestive complaints. However, these similarities do not confirm MCAS, and the Australian Society of Clinical Immunology and Allergy cautions against diagnosing it without meeting the required criteria.
Australian source: Australasian Society of Clinical Immunology and Allergy (ASCIA) — Mast cell activation syndrome information for health professionals (PDF)
5. Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS)
What is it?
ME/CFS is a complex, long-term illness involving significant fatigue and a range of other symptoms that can affect everyday functioning.
Common symptoms may include:
Severe or persistent fatigue that is not resolved by ordinary rest.
Unrefreshing sleep.
Difficulty concentrating or remembering things.
Muscle or joint pain.
Dizziness or light-headedness.
Post-exertional malaise (PEM): symptoms worsen after physical, mental or emotional effort, sometimes with a delayed onset and prolonged recovery.
What causes it?
The cause is not fully understood. ME/CFS can develop after infections, although other contributing factors may be involved.
How does it relate to POTS?
POTS and ME/CFS can occur together. Both can affect energy, concentration and everyday activities, but ME/CFS has a particularly important feature: post-exertional malaise. This is more than ordinary tiredness after exercise.
Australian source: Healthdirect — Myalgic encephalomyelitis / chronic fatigue syndrome
6. Pelvic Congestion Syndrome (PCS)
What is it?
Pelvic congestion syndrome is a possible cause of chronic pelvic pain associated with enlarged pelvic veins and blood flowing backwards or pooling in those veins.
Possible symptoms include:
A dull ache or heaviness in the pelvis.
Pain that worsens after standing or sitting for long periods.
Pelvic discomfort that may increase around menstruation.
Pain during or after sexual intercourse.
Enlarged veins in the pelvic or genital region in some cases.
What causes it?
Problems with vein valves or blood flow can contribute to increased pressure in pelvic veins.
How does it relate to POTS?
Both conditions may involve symptoms that are affected by being upright, but pelvic congestion syndrome is a distinct vascular condition. Pelvic pain or dizziness alone cannot identify its cause.
Australian source: Sydney Interventional Radiology — Pelvic congestion syndrome
Note: Pelvic congestion syndrome requires assessment because several other conditions can cause similar pelvic symptoms.
7. Gastroparesis
What is it?
Gastroparesis is a condition in which the stomach empties food into the small intestine more slowly than usual because stomach movement is impaired.
Common symptoms include:
Feeling full after eating only a small amount.
Bloating and nausea.
Vomiting after meals.
Abdominal discomfort or heartburn.
Reduced appetite and, in some cases, weight loss.
What causes it?
Gastroparesis can be associated with problems affecting the nerves or muscles involved in stomach movement. Diabetes and some types of surgery or infection can contribute, although the cause is not always known.
How does it relate to POTS?
Because the autonomic nervous system helps regulate digestion, some people with POTS experience gastrointestinal symptoms. However, bloating, nausea or early fullness do not necessarily mean someone has gastroparesis.
Australian source: Healthdirect — Gastroparesis
8. Endometriosis
What is it?
Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside the uterus, potentially causing inflammation, pain and scar tissue.
Common symptoms include:
Painful periods.
Persistent pelvic or abdominal pain.
Pain during or after sex.
Pain when going to the toilet.
Fatigue, bloating or bowel and bladder symptoms.
Difficulty becoming pregnant for some people.
What causes it?
The exact cause is not fully understood. Hormonal, immune and genetic factors may play a role.
How does it relate to POTS?
Endometriosis and POTS may occur in the same person, but one does not automatically cause the other. Both can affect daily functioning, and symptoms such as fatigue or abdominal discomfort can have multiple explanations.
Australian source: Healthdirect — Endometriosis
9. Raynaud's Phenomenon
What is it?
Raynaud's phenomenon affects blood flow to small blood vessels, usually in the fingers and toes. The blood vessels temporarily narrow in response to cold or stress.
Common symptoms include:
Fingers or toes becoming unusually cold.
Skin changing colour, often turning white or blue and then red as circulation returns.
Numbness, tingling or pain.
Symptoms triggered by cold temperatures or emotional stress.
What causes it?
Raynaud's can occur on its own, known as primary Raynaud's, or alongside another illness, known as secondary Raynaud's.
How does it relate to POTS?
Both conditions can involve circulation-related symptoms, but Raynaud's affects blood flow to the extremities, while POTS involves the body's response to being upright. They should not be treated as interchangeable conditions.
Australian source: Healthdirect — Raynaud's phenomenon
10. May-Thurner Syndrome
What is it?
May-Thurner syndrome is a vascular condition in which a nearby artery compresses a major vein in the pelvis, usually the left iliac vein. This can interfere with blood returning from the left leg.
Possible symptoms include:
Swelling or heaviness in one leg, particularly the left.
Leg pain or discomfort.
Enlarged veins or skin changes.
In some cases, deep vein thrombosis (a blood clot in a deep vein).
Some people have no symptoms.
What causes it?
It results from compression of the vein by surrounding anatomy. Not everyone with this anatomical compression develops symptoms or requires treatment.
How does it relate to POTS?
May-Thurner syndrome and POTS are different conditions. Both may be discussed in relation to circulation, but a person with POTS does not necessarily have a vascular compression syndrome.
The takeaway: Similar symptoms do not always mean the same condition
POTS and the conditions discussed above can involve overlapping experiences, including fatigue, dizziness, pain, digestive difficulties and changes in circulation.
However, these symptoms are not specific to one condition.
Some of these conditions can coexist, while others have different causes and require different investigations.
If you are experiencing persistent, unexplained or worsening symptoms, speak with your GP.
Keeping a record of when symptoms occur, what seems to trigger them and how they affect everyday life may help you explain your experience during an appointment.
Seek urgent medical care for concerning symptoms such as chest pain, severe shortness of breath, sudden weakness, a new severe headache, or fainting accompanied by significant symptoms. Call Triple Zero (000) for an emergency.
Important information
This article is for general educational purposes only. It does not provide a diagnosis, replace individual medical advice or recommend a particular treatment. Symptoms listed here can occur for many reasons, and only an appropriately qualified health professional can assess an individual's circumstances.
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