There are two parts of the autonomic nervous system, the sympathetic and the parasympathetic division. These two divisions work together to control all vital functions, including heart rate, blood pressure, breathing and digestion. When people have problems that give them orthostatic intolerance, there is often dysfunction somewhere in their autonomic nervous system. Any form of dysfunction in the autonomic nervous system is grouped under the term, ‘dysautonomia’. Dysautonomias can cause a variety of different symptoms, which has led to the definition of several subdiagnoses. Two examples are POTS and orthostatic hypotension. In POTS, the person’s heart rate increases significantly when they stand up, in orthostatic hypotension, their blood pressure drops significantly when standing up. In all dysautonomias, the sympathetic and parasympathetic nervous systems are not working together correctly.
Common Symptoms of POTS
- High/low heart rate
- Chest pain
- Dizziness or lightheadedness, especially when standing up, standing for prolonged periods of time or during long walks
- Fainting or near-fainting
- Exhaustion/fatigue
- Abdominal pain and bloating
- Nausea
- Nervous, jittery feeling
- Forgetfulness and trouble focusing (brain fog)
- Anxiety or depression
- Blurry vision
- Headaches and body pain/aches (may feel flu-like); neck pain
- Excessive or lack of sweating
- Insomnia and frequent awakenings from sleep, chest pain and racing heart rate during sleep, excessive sweating
- Shakiness/tremors especially with adrenaline surges
- Discoloration of feet and hands
- Exercise intolerance
- Diarrhea and/or constipation