When Is Low Blood Pressure Dangerous?

Healthcare providers consider low blood pressure (hypotension)—a reading below 90/60 millimeters of mercury (mm Hg)—benign, or not harmful, because it rarely causes symptoms. However, some people with low blood pressure may experience symptoms that indicate some body parts are not receiving enough oxygenated and nutrient-rich blood flow.

This article discusses when blood pressure becomes too low, symptoms to look for, and the next steps to ensure you get the necessary care.

When Is Low Blood Pressure Considered Dangerous?

Low blood pressure is dangerous when it drops below 90/60 mm Hg and is accompanied by symptoms.

Blood pressure is essential in ensuring all body parts receive oxygenated and nutrient-rich blood. On occasion, low blood pressure can interfere with this process. Some signs and symptoms to be aware of in which low blood pressure might be preventing the delivery of oxygenated and nutrient-rich blood throughout the body include:

• Confusion or dizziness
• Nausea
• Fainting or "blacking out"
• Feeling more tired than usual despite receiving seven to nine hours of sleep
• Headache or blurry vision
• Feelings of your heart skipping or missing beats or beating too fast or too slow

If you experience these symptoms, follow up with a healthcare provider for evaluation.

Underlying Conditions

Low blood pressure can occur for many different reasons. Most of the time, people who experience low blood pressure do not have any signs or symptoms and likely do not even realize their blood pressure has dropped to 90/60 mm Hg or lower.

Other conditions that can cause low blood pressure include:

• Addison's disease (a disease marked by the underproduction of cortisol)
• Dehydration
• Diabetes
• Heart conditions
• Hypothyroidism (an underactive thyroid)
• Neurological conditions (e.g., Parkinson's disease)
• Nutritional deficits (e.g., vitamin B12 and folic acid)
• Pregnancy or aging
  
• Specific medications (e.g., beta-blockers or erectile dysfunction medications containing nitroglycerine or narcotics)
  

Sometimes, low blood pressure can occur as a result of life-threatening situations. Examples include:

• Septic shock: When a person experiences a severe infection, such as from a bacterium, the toxins produced by the bacterium can cause problems with the body's ability to circulate oxygenated blood, leading to low blood pressure.
• Allergic reaction: A life-threatening allergic reaction known as anaphylaxis can impact the body's ability to circulate oxygen and nutrients throughout the body, which can cause low blood pressure.
• Decrease in circulating blood volume: Significant blood loss due to events such as a major traumatic event or severe internal bleeding can reduce circulating blood volume and cause low blood pressure.
  

Low Blood Pressure Symptoms

Often, people with low blood pressure don't experience any symptoms. However, if blood pressure goes too low or you experience a condition in which hypotension is likely, such as significant blood loss or dehydration, be aware of the following symptoms:

• Blurry vision
• Confusion or altered mental status
• Dizziness, light-headedness, or fainting
• Feeling tired or weak despite having gotten plenty of rest
  
• Headache, neck or back pain
  
• Heart beating too fast or too slow or feeling like it is missing beats
• Nausea
  

Average Blood Pressure Ranges

Healthcare providers consider normal blood pressure to be less than or equal to 120/80 mm Hg. Blood pressure that is 90/60 mm Hg or lower is considered low. The chart below illustrates the average blood pressure ranges.

Potential Risks and Complications of Low Blood Pressure

Having normal blood pressure ensures that the blood delivers oxygen and essential nutrients throughout the body to ensure overall health and wellness. Experiencing lower-than-normal blood pressure, especially with associated signs and symptoms, can potentially cause other risks and complications, affecting the following organs:

• Brain: A decrease in oxygenation and nutrients can cause stroke-like symptoms or changes in mental status, such as confusion.
• Kidneys: Without proper oxygenation and nutrients, the kidneys could suffer from acute renal injury, which could impair the kidneys' ability to function correctly.
• Heart: The heart can suffer damage from a lack of oxygen and nutrients, which could lead to a heart attack or heart failure.
  

People with episodic or continuous low blood pressure should routinely see their providers to monitor any potential risks and complications associated with low blood pressure.

Certain populations are more likely to experience low blood pressure and should monitor it closely, including:

• Older adults: Blood vessel flexibility, blood pressure–regulating hormones, and various medications can cause blood pressure changes as people age. Low blood pressure can also put older adults at an increased risk for falls.
• Pregnant people: A condition known as supine hypotension syndrome or aortocaval compression syndrome can cause low blood pressure in pregnant people. When lying flat or on the right side, the weight of the growing fetus can put pressure on a pregnant person's main blood vessels, preventing proper blood flow and leading to low blood pressure.

What to Do If Blood Pressure Is Too Low: Home Care and Remedies

Since the majority of low blood pressure, or hypotension, has no symptoms and does not interfere with normal activities of daily living, there is rarely any medications or treatments needed. However, proactive lifestyle interventions, such as the following, can help alleviate hypotension:

• Ensure you drink adequate amounts of water.
• Keep your legs elevated or wear compression socks to keep blood moving in the legs
• Eat a healthy diet with foods high in folate and vitamin B12, which can prevent anemia and help maintain a normal blood pressure
• Change positions, such as from lying to sitting then sitting to standing, slowly to allow the body's mechanisms to manage blood pressure adapt to the positions changes

How to Prevent Low Blood Pressure

If you have or experience low blood pressure, consider ways to prevent episodes of low blood pressure, such as:

• Change positions slowly (e.g., move from lying to sitting and then from sitting to standing).
• Drink plenty of fluids to stay hydrated.
• Eat a healthy diet with foods high in vitamin B12 and folate, such as legumes, asparagus, and leafy greens.
• Increase physical activity to keep muscles conditioned to help blood move effectively throughout the body.
• Wear compression socks.
  

When to Contact a Healthcare Provider

Even if you usually experience low blood pressure, any signs or symptoms that occur should be evaluated by a qualified healthcare provider:

• Dizziness, light-headedness or fainting
• Blurry vision or headaches
• Nausea
• Losing balance and falling

When you see a healthcare provider for low blood pressure, you can expect the following:

• A complete medical history and full physical examination
• Laboratory work such as testing for infection, hormone conditions like low thyroid function or diabetes, or blood disorders like anemia
• An electrocardiogram to identify any heart rhythm disturbances that could cause low blood pressure
• Other interventions, as determined based on the suspected underlying cause of hypotension

If you experience any signs or symptoms of shock, call emergency medical response immediately for a rapid evaluation:

• Cold and sweaty skin
• Rapid breathing
• Heart rate that is too fast or too slow
• Skin tone becomes bluish or dusky

Summary

Blood pressure below 90/60 mm Hg is considered low blood pressure, or hypotension. It's typically not dangerous and doesn't require treatment. However, some people may experience symptoms such as confusion, dizziness, fainting, or nausea with low blood pressure. People with symptoms should follow up with a healthcare provider for evaluation and treatment.