We are used to hearing about the perils of high blood pressure. But what about low blood pressure — also known as hypotension? Fortunately, hypotension without overt symptoms is rarely anything to worry about. However, in certain groups of people, hypotension can be a sign of a wide range of underlying conditions. In this article, we will answer the question "can your blood sugar be too low", the signs, symptoms, and causes of hypotension so you can get a better idea of whether and when you should talk to your healthcare provider. We will also provide you with some tricks to deal with low blood sugar.

What does blood pressure have to do with health?

Blood pressure is the force exerted by circulating blood against your blood vessels and can be easily measured with blood pressure cuffs and other devices that detect and quantify this force. You’ve probably seen blood pressure written like this: 120/80 mmHg.

• The higher of the two numbers is the systolic pressure, which is the pressure in the arteries when the heart is beating.
  
• The lower number measures the diastolic pressure, the pressure in the arteries when the heart rests between beats.

In 2017, the American College of Cardiology/American Heart Association (ACC/AHA) hypertension guidelines recommended a target blood pressure of 130/80 mmHg to reduce cardiovascular disease risk.

The risks of high blood pressure

Most Americans probably hear and believe that the lower the blood pressure, the better, because high blood pressure is a well-publicized, medically risky condition. Indeed, there are a plethora of studies connecting high blood pressure (hypertension) with cardiovascular disease and mortality. Furthermore, some studies have shown that systolic blood pressures as low as 90 mmHg is associated with a reduced risk for cardiovascular disease. The success of diets such as the Mediterranean and DASH diets are linked to, among other benefits, their ability to reduce hypertension. 

But can blood pressure be too low?

Very low blood pressure is called hypotension, and there is no one-size-fits-all definition of this condition. Among the many forms of hypotension that exist, two main types that we’ll focus on are:

• Absolute hypotension, which is generally considered a systolic blood pressure reading lower than 90 mmHg for the top number or a diastolic reading lower than 60 mmHg for the bottom number.
  
• Orthostatic hypotension, which involves an abnormal blood pressure in response to standing. Orthostatic hypotension has been defined by a systolic blood pressure drop ≥20 mmHg, an absolute systolic blood pressure ≤90 mmHg and/or a diastolic BP drop ≥10 mmHg within three minutes of standing.

Most of the time, hypotension in and of itself isn’t an issue. It’s only when hypotension is associated with overt symptoms that the condition needs to be addressed. Many of the symptoms of hypotension occur due to suboptimal organ perfusion: the delivery of oxygen-rich blood to the organs in your body so they can function appropriately. These symptoms include:

• Blurred or fading vision
• Dizziness and lightheadedness
• Fainting
• Trouble concentrating
• Nausea

Furthermore, extremely low blood pressure can lead to shock — which can manifest as the following:

• Shallow breathing
• A weak and rapid pulse
• Confusion
• Cold skin
• Pallor

What causes low blood pressure?

There are several potential underlying causes of low blood pressure, some of them more serious than others. Because the symptoms of hypotension belie the underlying cause, it’s important to work with your healthcare provider to determine why you might have low blood pressure so that you can treat it appropriately.

Medications are one of the most common causes of low blood pressure. According to the Cleveland Clinic, several different medications can cause hypotension:

• Medications for controlling hypertension
• Antidepressants
• Heart failure medications
• Medications for erectile dysfunction
• Antipsychotics
• Recreational drugs, alcohol, and over-the-counter painkillers

Hypotension can also be caused by less severe issues that are often more easily remedied:

• Dehydration
• The first 24 weeks of pregnancy
• Vitamin B12 and folic acid deficiencies
• Allergic reactions

• Severe infections
• Endocrine disorders, such as hypothyroidism, parathyroid disease, and adrenal insufficiency

Generally, these conditions have very specific signs and symptoms that lead to their detection and diagnosis. Hypotension is often a “side effect” of these conditions rather than a sign or symptom that aids in diagnosis. With appropriate disease management, the associated hypotension often resolves. 

However, there are more serious situations that can be a bit trickier to handle:

• Heart failure. In clinical trials, low blood pressure is reported in 10-15% of patients with heart failure. One of the tricky things about low blood pressure in heart failure patients is that it can be hard to increase the dosage of many life-saving medications because they also tend to lower blood pressure. Without direct evidence, a 2020 review recommended an algorithm to manage heart failure drugs in clinical settings. The authors recommended using higher doses of life-saving medications even in the presence of hypotension.
  
• Dialysis. Individuals on dialysis often suffer from intradialytic hypotension (IDH). As with hypotension generally, a strict definition for IDH doesn’t exist. The most common definitions involve systolic blood pressures <90 mmHg or a decline in systolic blood pressures of >20 mmHg. The authors of a 2020 review suggest that IDH prevention lies in applying smart methodologies — including machine learning — that can detect subclinical abnormalities in fluid status and tissue perfusion. However, more research is needed to understand IDH and how to appropriately address it.
  
• Stroke. Low blood pressure early after hospital admission for acute strokes has been associated with negative outcomes even after full adjustment for potential confounding factors. The authors of a 2021 study argued that low blood pressure during a stroke is “clearly not a benign phenomenon.” They point out that a J-shaped relationship often exists between blood pressure and adverse outcomes in cardiovascular disease. This means that very high and very low blood pressure are often associated with worse outcomes.
  
• Parkinson’s disease. Finally, there is evidence that orthostatic hypotension is common in people with Parkinson’s disease. However, one study found no evidence that orthostatic hypotension leads to an increased risk of developing Parkinson’s disease.

Low blood pressure and exercise

Healthcare providers often point to the many cardiovascular benefits associated with exercise. However, this doesn’t mean that exercise protects you from either hyper- or hypotension. In fact, since the 1970s, it has been documented that blood pressure can fall significantly after exercise due to a phenomenon called post-exercise hypotension.

Although post-exercise hypotension is more common in people with hypertension, it can also occur in people with normal and low blood pressure. Symptoms include lightheadedness, tunnel vision, blurred vision, and a loss of consciousness following aerobic and resistance exercise. If you suffer from a bout of hypotension after exercising, you can take the following actions:

• Hydrate. One case report showed that ingesting one liter of water 15 minutes before exercise was effective at preventing post-exercise fainting. Postexercise fluid replacements that contain electrolytes are also recommended.
  
• Breathe. Inspiratory resistance breathing was initially developed as a resuscitation method, but at least one study has documented how this breathing method may improve orthostatic tolerance.
  
• Cool down. Body cooling (cryotherapy or cold water immersion) is another strategy to enhance exercise recovery and prevent post-exercise syncope, particularly in hot and humid conditions.

If you regularly experience post-exercise hypotension, this could be due to sustained vasodilation caused by histamine. One pharmacological approach to preventing exercise-induced hypotension is antihistamine therapy. Talk with your healthcare provider to determine whether this or another intervention could help you if it has been determined that you do experience exercise-induced hypotension.

Easy ways to manage low blood pressure

Unless you are experiencing obvious symptoms, a single lower-than-normal blood pressure reading is no cause for alarm. Furthermore, it is generally recommended that people with heart failure and orthostatic hypotension stay on their medications despite hypotension. 

However, there are some simple lifestyle adjustments you can follow to keep your blood pressure from going too low or too high. Check out these recommendations from the Cleveland Clinic:

• Manage your diet. Salt tends to increase your blood pressure, so you can consider adding more salt to your diet if your blood pressure is trending unusually low. However, be sure to consult with your healthcare provider before undergoing any dietary modifications.
  
• Take your medications. As we discussed above, it is generally recommended that you continue to take your medications, even if they tend to lower blood pressure. Consult with your healthcare provider before discontinuing any medications.
  
• Wear compression socks. Compression socks put light pressure on your legs and feet to push blood upward and raise your blood pressure.
  
  
• Take it slow. Avoid standing up too quickly, especially if you experience orthostatic hypotension.
  
• Have a seat. Sit down if you notice yourself feeling dizzy or lightheaded. Falls from a standing height can put you at risk for severe or even catastrophic injuries.
  
• Record your symptoms. Tracking the activities that are associated with your symptoms can help your healthcare provider identify any underlying cause(s) of hypotension so they can recommend an appropriate treatment plan.

Key takeaways

Can blood pressure be too low? Most healthcare providers agree that low blood pressure is rarely a problem in the absence of symptoms, such as dizziness, lightheadedness and nausea. And while hypotension often results from common medications and relatively benign causes, it can sometimes be associated with more severe conditions. In the case of heart failure, chronic kidney disease, stroke, and Parkinson’s disease, underlying hypotension is complex and not well understood. Therefore, you should visit your healthcare provider immediately if you are concerned about symptoms of hypotension.