What Causes Low Diastolic Blood Pressure?

Low diastolic blood pressure (the bottom number in a blood pressure reading) can result from various factors and medical conditions. Diastolic blood pressure represents the pressure in your arteries between heartbeats, when the heart is at rest and refilling with blood. It’s essential for proper blood flow to the organs and tissues. Here are some common causes of low diastolic blood pressure:

  • Orthostatic Hypotension: This condition occurs when there’s a sudden drop in blood pressure when you change position, such as standing up from a sitting or lying position. It can cause low diastolic blood pressure and is often related to dehydration, autonomic nervous system dysfunction, or certain medications.
  • Dehydration: Insufficient fluid intake or excessive loss of fluids (e.g., through vomiting, diarrhea, excessive sweating, or inadequate fluid intake) can lead to low blood pressure, including low diastolic pressure.
  • Medications: Some medications, particularly antihypertensive drugs, can lower both systolic and diastolic blood pressure. This is often the desired effect when treating high blood pressure, but if the medication dosage is too high or other factors come into play, it can lead to excessively low diastolic pressure.
  • Shock: Any condition that leads to shock, such as severe infections, severe allergic reactions (anaphylaxis), or heart conditions like cardiogenic shock, can result in very low diastolic blood pressure. Shock is a medical emergency.
  • Heart Problems: Conditions like heart failure, which affect the heart’s ability to pump blood effectively, can lead to low diastolic blood pressure. Reduced cardiac output can result in decreased blood pressure during diastole.
  • Arrhythmias: Irregular heart rhythms, such as bradycardia (slow heart rate) or certain types of atrial fibrillation, can affect the heart’s ability to fill with blood during diastole, leading to low diastolic pressure.
  • Autonomic Nervous System Disorders: Dysfunction of the autonomic nervous system, which controls various bodily functions, including blood pressure regulation, can result in low diastolic pressure.
  • Endocrine Disorders: Conditions like Addison’s disease (adrenal insufficiency) or thyroid disorders can affect blood pressure regulation and potentially lead to low diastolic pressure.
  • Hormonal Changes: Hormonal fluctuations, such as those associated with pregnancy, can lead to changes in blood pressure, including low diastolic pressure.
  • Anemia: Severe anemia, characterized by a low red blood cell count and reduced oxygen-carrying capacity, can lead to low blood pressure, including diastolic pressure.
  • Malnutrition: Inadequate intake of essential nutrients, including electrolytes like potassium, can lead to low blood pressure.
  • Idiopathic Hypotension: In some cases, low diastolic blood pressure may not have an identifiable cause and is referred to as idiopathic hypotension.

Low diastolic blood pressure can result in symptoms like dizziness, fainting, fatigue, and cognitive impairment. The underlying cause of low diastolic pressure will determine the appropriate treatment, which may include addressing dehydration, adjusting medications, managing underlying medical conditions, or using other interventions to raise blood pressure. If you experience persistent low diastolic blood pressure or concerning symptoms, consult a healthcare provider for evaluation and guidance.