Published: 18 Jun 2025

ICD9: 458.9      ICD10: I95.9      ICD11: BA2Z

Hypotension, or low blood pressure, occurs when your blood pressure is lower than normal.
While a single low reading might not be cause for concern, persistently low blood pressure can lead to inadequate blood flow to the brain and other vital organs.

What is considered low blood pressure?

Generally, blood pressure readings below 90 mmHg systolic (the top number) or 60 mmHg diastolic (the bottom number) are considered hypotension.

Symptoms of Low Blood Pressure:

Many people with low blood pressure experience no symptoms at all. However, when blood pressure drops too low, it can cause a variety of symptoms, including:

Dizziness or lightheadedness: This is one of the most common symptoms, especially when standing up quickly (orthostatic hypotension).
Fainting (syncope): A more severe form of dizziness that can lead to a temporary loss of consciousness.
Blurred or distorted vision: Reduced blood flow to the eyes can affect vision.
Nausea: Hypotension can disrupt digestive function.
Fatigue: Inadequate blood flow to muscles and organs can cause tiredness.
Difficulty concentrating: The brain needs a consistent blood supply to function properly.
Cold, clammy, pale skin: Blood is shunted away from the skin to preserve blood flow to vital organs.
Rapid, shallow breathing: The body may try to compensate for low blood pressure by breathing faster.
Dehydration and unusual thirst.

Causes of Low Blood Pressure:

Hypotension can have a variety of causes, including:

Dehydration: Reduced blood volume can lead to lower blood pressure.
Heart problems: Conditions like heart valve problems, heart failure, or arrhythmias (irregular heartbeats) can affect the heart's ability to pump blood effectively.
Endocrine problems: Conditions like hypothyroidism, hyperthyroidism, adrenal insufficiency (Addison's disease), and low blood sugar (hypoglycemia) can contribute to low blood pressure.
Pregnancy: Blood pressure often decreases during pregnancy.
Nutritional deficiencies: Deficiencies in vitamin B12 and folate can lead to anemia, which can contribute to low blood pressure.
Medications: Many medications, including diuretics, alpha-blockers, beta-blockers, some antidepressants, and medications for Parkinson's disease or erectile dysfunction, can lower blood pressure.
Severe infection (septicemia): Septic shock can cause a dramatic drop in blood pressure.
Severe allergic reaction (anaphylaxis): Anaphylactic shock can also cause a sudden and severe drop in blood pressure.
Blood loss: Significant blood loss, whether from injury or internal bleeding, can lead to hypotension.
Prolonged bed rest: Can weaken the cardiovascular system.
Nervous system disorders: Some disorders affecting the nervous system can cause orthostatic hypotension.
Idiopathic Hypotension: Sometimes, no underlying cause can be found for chronic low blood pressure.

Types of Hypotension:

Orthostatic hypotension (Postural hypotension): This is a sudden drop in blood pressure that occurs when you stand up from a sitting or lying position.
Postprandial hypotension: This is a drop in blood pressure that occurs after eating. It's more common in older adults and people with certain medical conditions.
Neurally mediated hypotension: This type of hypotension occurs after standing for long periods. It is thought to be due to a miscommunication between the heart and the brain.
Severe hypotension related to shock: Shock can occur for many reasons, including decreased blood volume (hypovolemic shock), heart problems (cardiogenic shock), severe allergic reaction (anaphylactic shock), or severe infection (septic shock).

Diagnosis:

Diagnosis of hypotension typically involves:

Blood pressure measurement: Readings are taken while sitting, standing, and lying down to check for orthostatic hypotension.
Medical history and physical exam: To identify potential underlying causes.
Blood tests: To check for anemia, thyroid problems, and other conditions.
Electrocardiogram (ECG): To assess heart function.
Tilt table test: To evaluate how blood pressure and heart rate respond to changes in position.

Treatment:

Treatment for hypotension depends on the underlying cause and the severity of the symptoms. Some general recommendations include:

Lifestyle changes:
Increase fluid intake: Drink plenty of water to maintain blood volume.
Increase salt intake: Consult with your doctor before increasing salt intake, as it can have other health implications.
Avoid alcohol: Alcohol can lower blood pressure.
Eat small, frequent meals: This can help prevent postprandial hypotension.
Stand up slowly: This can help prevent orthostatic hypotension.
Wear compression stockings: These can help improve blood circulation.
Elevate the head of your bed: This can help reduce orthostatic hypotension.
Medications: In some cases, medications may be prescribed to raise blood pressure. These medications need to be prescribed and monitored by a doctor.
Treating underlying conditions: If hypotension is caused by an underlying medical condition, treating that condition can help improve blood pressure.

When to See a Doctor:

It's important to see a doctor if you experience persistent symptoms of low blood pressure, especially dizziness, lightheadedness, fainting, or blurred vision. Seek immediate medical attention if you experience any symptoms of shock, such as rapid, shallow breathing, cold, clammy skin, or confusion.

Important Considerations:

Self-treating low blood pressure can be dangerous. Always consult with a healthcare professional before making any significant changes to your diet, medication, or lifestyle.
Low blood pressure can be a sign of a serious underlying medical condition. It's essential to identify and treat the underlying cause to prevent complications.
The "ideal" blood pressure varies from person to person. Some individuals naturally have lower blood pressure without experiencing any symptoms or health problems.

This information is for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.