A dysfunction of the nerves that regulate nonvoluntary body functions, such as heart rate, blood pressure, and sweating.

When to seek immediate medical care

See a doctor immediately if:

  • Low blood pressure
  • Nausea
  • Bloating
  • Weight loss
  • Fainting

When to make a doctor's appointment

Make an appointment to see a doctor if:

  • Lightheaded when standing

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