what causes low blood pressure?

Low blood pressure, or hypotension, can be caused by a variety of factors, which can be categorized into several main groups:

Temporary and Reversible Causes

• Dehydration: This can result from vomiting, diarrhea, fever, or not drinking enough fluids, leading to a decrease in blood volume234.
• Prolonged Bed Rest: Long periods of inactivity can cause orthostatic hypotension135.
• Pregnancy: Increased demand for blood from both the pregnant person and the growing fetus can lead to low blood pressure134.
• Postprandial Hypotension: A drop in blood pressure after eating, more common in older adults and those with autonomic dysfunction4.
• Heat Exposure: Heavy sweating in hot environments can lead to dehydration and low blood pressure2.

Medication-Related Causes

• High Blood Pressure Medications: Diuretics, beta-blockers, calcium-channel blockers, and ACE inhibitors can cause low blood pressure as a side effect135.
• Other Medications: Drugs for Parkinson’s disease, antidepressants, erectile dysfunction medications, and certain antipsychotics can also lower blood pressure135.

Underlying Medical Conditions

• Heart Problems: Conditions such as heart failure, heart valve disease, heart attack, and abnormally low heart rate (bradycardia) can lead to low blood pressure125.
• Endocrine Disorders: Hypothyroidism, adrenal insufficiency (Addison's disease), diabetes, and low blood sugar (hypoglycemia) can affect blood pressure regulation125.
• Nervous System Disorders: Conditions like Parkinson’s disease, multiple system atrophy, Lewy body dementia, and autonomic neuropathy can disrupt blood pressure control24.
• Nutritional Deficiencies: Lack of essential vitamins such as B12 and folic acid can lead to anemia, which in turn can cause low blood pressure135.

Life-Threatening Conditions

• Blood Loss: Significant blood loss from trauma or internal bleeding can severely lower blood pressure15.
• Sepsis and Septic Shock: Severe bacterial infections can lead to dangerously low blood pressure135.
• Anaphylactic Shock: A severe allergic reaction can cause a sudden and dangerous drop in blood pressure135.

Other Factors

• Aging: Older adults may experience age-related declines in blood pressure regulation12.
• Alcohol Use: Drinking alcohol can increase the risk of orthostatic hypotension23.
• Genetic Factors: Some people may naturally have low blood pressure due to genetic reasons3.

These causes can lead to various forms of hypotension, including orthostatic (postural) hypotension, neurally mediated hypotension, and other types of low blood pressure. If symptoms persist or worsen, it is important to seek medical attention to determine the underlying cause and appropriate treatment.