Low diastolic blood pressure can be caused by several factors and conditions, including:

• Aging and Artery Stiffness: With age, arteries lose elasticity and become stiff, which can lower diastolic pressure because the arteries cannot spring back effectively between heartbeats. This stiffening also raises systolic pressure, increasing the gap between systolic and diastolic readings.
• Medications: Some medications, particularly alpha-blockers, diuretics, Parkinson’s disease drugs, antidepressants, and certain erectile dysfunction drugs, can dilate blood vessels or reduce blood volume, leading to lower diastolic pressure.
• Medical Conditions:
  • Heart problems such as bradycardia (slow heart rate), heart valve disease, and heart failure can cause low diastolic blood pressure.
  • Hormonal or endocrine disorders like Addison’s disease, hypothyroidism, or hyperthyroidism.
  • Dehydration reduces blood volume, lowering blood pressure.
  • Blood loss due to injury or internal bleeding.
  • Severe infections (septic shock) or severe allergic reactions (anaphylaxis).
  • Nutritional deficiencies such as low vitamin B-12, folate, or iron causing anemia.
• Lifestyle and Other Causes:
  • Prolonged bed rest can reduce artery tone.
  • Excess alcohol intake can dilate blood vessels and affect heart function.
  • Standing for prolonged periods can cause blood pooling in legs and lower diastolic pressure.
  • Pregnancy, as blood vessels expand rapidly.
  • Diabetes and atherosclerosis causing stiff arteries.
• Dehydration and fluid loss from excessive sweating, vomiting, diarrhea, or diuretic use also contribute to low diastolic blood pressure.

Low diastolic blood pressure can sometimes indicate underlying health issues, especially when accompanied by symptoms. Addressing the cause, managing medications, and ensuring proper hydration and nutrition are common approaches to treatment. This comprehensive view incorporates causes related to aging, medication, heart and endocrine conditions, lifestyle factors, and others.