An Overview of Low Blood Pressure

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Low blood pressure (hypotension) is primarily a concern if it produces symptoms or if you have a sudden drop in blood pressure. Maintaining a healthy blood pressure (below 120/80 millimeters of mercury, or mmHG) can protect you from a host of health issues. But blood pressure that is too low—defined as below 90/60 mmHg—can prevent your organs from getting adequate amounts of the oxygenated blood they need to function properly. Hypotension is of particular concern for vital organs like the brain.

Symptoms

If you have low blood pressure but don’t experience any symptoms, then your blood pressure is most likely not a problem. However, if you do experience symptoms, you need to talk to your healthcare provider. Signs and symptoms of low blood pressure include:

  • Lightheadedness or dizziness
  • Fainting (syncope)
  • Blurred vision
  • Difficulty concentrating
  • Cool, clammy, pale skin
  • Shallow, rapid breathing
  • Thirst and dehydration
  • Fatigue
  • Nausea

Causes

There are many different reasons why you may be experiencing symptoms of low blood pressure. The three main types of low blood pressure have different causes.

Orthostatic hypotension is a drop in blood pressure when you stand suddenly or rise up after lying down. Orthostatic hypotension is seen in a variety of conditions including pregnancy, dehydration, anemia, heart conditions, thyroid disorders, Addison's disease, diabetes, low blood sugar, and nervous system disorders including Parkinson's disease. It is also common in older age, especially after meals.

You may also experience it as a side effect of high blood pressure medications, nitrates used to treat chest pain, medications for erectile dysfunction, some antidepressants, and antipsychotic medications.

Neurally mediated hypotension is seen in disorders of the autonomic nervous system, including postural orthostatic tachycardia syndrome (POTS) and vasovagal syncope. In this type, low blood pressure occurs after extended periods of standing.

Emotional stress can also be a trigger of neurally mediated hypotension.

Severe hypotension related to shock is a medical emergency that requires immediate treatment. It is seen in major blood loss, septic shock, severe fluid loss, cardiogenic shock from a heart attack or arrhythmia, and vasodilatory shock seen in head injury, liver failure, or anaphylaxis.

Blood Pressure Readings

The top number is the systolic blood pressure, which refers to the pressure created in the arteries with each heartbeat.

The bottom number is the diastolic blood pressure, or the pressure in the arteries when the heart is resting between each beat.

Diagnosis

Your doctor might take your blood pressure as part of a routine check-up, part of a sick visit, or after you've reported any of the above symptoms.

When low blood pressure is detected (a reading below 90/60 mmHg), the doctor's goal is then to find the underlying cause. They will start this investigation by asking you about your personal medical history, including any medications and supplements you are taking.

Your doctor also might recommend the following tests:

  • Blood tests to identify conditions that may be impacting your blood pressure, like diabetes or anemia
  • Electrocardiogram (ECG), which can indicate issue with your heart's rhythm and structural abnormalities
  • Echocardiogram, which produces detailed images of your heart's function and structure
  • Stress test to monitor your heart rate and blood pressure while walking on a treadmill
  • Tilt table test to determine if your blood pressure is impacted by standing from a prone position

Treatment

Because low blood pressure can be the result of many different conditions, treatment may be specific to the condition causing it. Managing health conditions such as diabetes, heart disease, arrhythmias, liver disease, thyroid disease, and other hormonal disorders will help prevent low blood pressure episodes.

Here are some common causes of low blood pressure with associated treatments:

  • Decreased blood volume from dehydration or blood loss is treated with replacing fluids or, if severe, with transfusion.
  • Hypotension due to anemia caused by nutritional deficiencies can be resolved with the appropriate vitamins and minerals.
  • Your medications may need to be adjusted if they are the cause. Always do this in consultation with your doctor rather than discontinuing them abruptly.
  • If orthostatic hypotension is primarily due to aging, you can learn to avoid things that provoke the problem, such as getting up suddenly from a seated or reclining position.
  • Anaphylaxis is a severe allergic reaction that can be fatal. Those who are at risk often carry an epinephrine self-injector and try diligently to avoid their trigger. It requires emergency treatment.
  • Septic shock and other forms of shock require an immediate medical response. Supportive care—including intravenous (IV) fluid and medications to raise your blood pressure (vasopressors)—are often required, as well as treating the underlying cause.

Pregnancy hypotension will usually resolve after giving birth. Towards the end of pregnancy, it is helpful to recline on the left side, which reduces pressure on the blood vessels from the growing uterus and fetus.

Neurally-mediated low blood pressure is most often seen in younger individuals and the condition usually resolves quickly without treatment.

Staying hydrated, exercising regularly, eating well, and reducing stress all help keep blood pressure levels in the healthy range.

A Word From Verywell

Generally, low blood pressure is most significant when it occurs suddenly or when it is the result of another disease. If you are experiencing any symptoms of hypotension, do not delay in speaking with your healthcare provider.

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