Low Blood Pressure (Hypotension)
What is low blood pressure?
Hypotension, or low blood pressure, is when your blood pressure is much lower than expected. It can happen either as a condition on its own or as a symptom of a wide range of conditions. It may not cause symptoms, but when it does, it can require medical attention.
Hypotension has two definitions:
- Absolute hypotension: Your resting blood pressure is below 90/60 mmHg (millimeters of mercury).
- Orthostatic hypotension: Your blood pressure drops within three minutes of you standing up from a sitting position. The drop must be 20 mmHg or more for your systolic (top) pressure and 10 mmHg or more for your diastolic (bottom) pressure. Another name for this is postural hypotension because it happens with changes in posture.
Measuring blood pressure involves two numbers, top and bottom, in mm/Hg.
- Systolic (top number): Your systolic pressure is the pressure on your arteries each time your heart beats. To find your systolic pressure, a healthcare provider* inflates a cuff that squeezes your arm. At the same time, they listen to your pulse at a point below the cuff. Your systolic pressure is when they can’t hear your pulse anymore because the cuff’s pressure is stronger than the pressure from your heart pumping.
- Diastolic (bottom number): That number is how much pressure your arteries are under between heartbeats. The provider will keep listening for your pulse to find your diastolic pressure while they deflate the cuff. Your diastolic pressure is the number where they can again hear your heartbeat as the cuff deflates.
*Thanks to technological advances, many modern devices can measure your blood pressure automatically. These devices are now recommended for use instead of measuring blood pressure with the traditional stethoscope method.
What is the difference between hypotension vs. hypertension?
Hypotension and hypertension are opposite conditions.
- Hypertension: The prefix “hyper-” means “too high.”
- Hypotension: The prefix “hypo-” means “too low.”
Who does it affect?
Hypotension can affect people of any age and background, depending on why it happens. However, it's more likely to cause symptoms in older people (especially orthostatic hypotension). It can also happen with no symptoms to people who are very physically active, which is more common in younger people.
How common is this condition?
Because low blood pressure is common without any symptoms, it’s impossible to know how many people it really affects overall. However, orthostatic hypertension seems to be more and more common as you get older. An estimated 5% of people have it at age 50, while that figure climbs to more than 30% in people over 70.
How does this condition affect my body?
Under normal circumstances, your body can automatically control your blood pressure and keep it from dropping too much. If it starts to drop, your body tries to compensate for that, either by speeding up your heart rate or constricting blood vessels to make them narrower. Symptoms of hypotension happen when your body can’t compensate enough to offset the drop in blood pressure.
For many people, hypotension doesn't cause any symptoms. Many people don't even know their blood pressure is low unless they get their blood pressure measured.
For people with symptoms, the effects depend on why hypotension is happening, how fast it develops and what caused it. Slow decreases in blood pressure happen normally, so hypotension becomes more common as people get older. Fast decreases in blood pressure can mean certain parts of your body aren’t getting enough blood flow. That can have effects that are unpleasant, disruptive or even dangerous.
Symptoms and Causes
What are the symptoms?
The most common symptoms of low blood pressure happen because your brain isn't getting enough blood flow. These include:
- Dizziness or feeling lightheaded.
- Fainting or passing out (syncope).
- Nausea or vomiting.
- Blurred or distorted vision.
- Fast, shallow breathing.
- Fatigue or weakness.
- Feeling tired, sluggish or lethargic.
- Confusion or trouble concentrating.
- Agitation or other unusual changes in behavior (a person not acting like themselves).
What causes low blood pressure?
Hypotension can happen for a wide range of reasons.
- Orthostatic hypotension. This happens when you stand up too quickly and your body can’t compensate with more blood flow to your brain.
- Central nervous system diseases. Conditions like Parkinson's disease can affect how your nervous system controls your blood pressure. People who have hypotension because of these conditions may feel the effects of low blood pressure after eating because their digestive system uses more blood as it works to digest food.
- Low blood volume. Blood loss from severe injuries can cause low blood pressure. Dehydration can also contribute to low blood volume.
- Life-threatening conditions. These conditions include irregular heart rhythms (arrhythmias), pulmonary embolism, heart attacks and collapsed lung. Life-threatening allergic reactions (anaphylaxis) or immune reactions to severe infections (sepsis) can also cause hypotension.
- Heart and lung conditions. When your heart beats too fast or too slow, or if your lungs aren't working as they should, both can lead to hypotension.
- Prescription medications. Hypotension can happen with medications that treat blood pressure, heart failure, erectile dysfunction, neurological problems, depression and more.
- Alcohol or recreational drugs. Recreational drugs can lower your blood pressure, as can alcohol (alcohol’s effect only lasts a short time, and long-term overuse of alcohol can cause high blood pressure). Though not technically medications, certain herbal supplements, vitamins or home remedies can also lower your blood pressure, which is why you should always include these when you tell your healthcare provider what medications you’re taking.
- Orthostatic hypotension is possible in the first and second trimesters of pregnancy. Bleeding or other complications of pregnancy can also cause low blood pressure.
- Extreme temperatures. Being too hot or too cold can affect hypotension and make its effects worse.
Is hypotension contagious?
No, hypotension isn’t contagious, so you can’t get it from someone else or pass it to others.
Diagnosis and Tests
How is it diagnosed?
Hypotension itself is easy to diagnose. All it takes is taking your blood pressure. However, figuring out why you have hypotension is another story. If you have symptoms, a healthcare provider will likely use a variety of tests to figure out why it’s happening and if there’s any danger to you because of it.
What tests will be done to diagnose this condition?
Tests that are likely with hypotension include those listed below.
Tests on your blood and urine can look for any potential problems like:
- Vitamin deficiencies.
- Thyroid or hormone problems
- Low iron levels (anemia).
- Pregnancy test (for anyone who can become pregnant).
If doctors suspect a heart or lung problem behind your hypotension, they’ll likely use imaging tests to confirm or rule out those suspicions. These tests include:
- Computed tomography (CT) scans.
- Magnetic resonance imaging (MRI).
- Echocardiogram or similar ultrasound-based tests.
These tests look for specific problems with your heart or other body systems.
Management and Treatment
How is it treated, and can it be cured?
Treating hypotension usually starts with finding out why it’s happening. If that cause is treatable directly, hypotension will usually get better on its own. An example of this is hypotension that happens because of an injury and blood loss. Repairing that injury and replacing the lost blood (such as with a blood transfusion) will stop hypotension as long as the repair to the injury holds. If you take medications that affect your blood pressure, your healthcare provider may change your dosage or have you stop taking that medication entirely.
If the cause remains a mystery, it’s also possible to treat it directly. However, curing hypotension is only possible if there’s an underlying cause that’s curable.
What medications/treatments are used?
Treating hypotension directly usually happens in one of three ways:
- Increasing blood volume. This method, also known as fluid resuscitation, involves infusing fluids into your blood. Examples of this include intravenous (IV) fluids, plasma or blood transfusions.
- Making blood vessels constrict. Just as there are medications that lower your blood pressure by relaxing blood vessels in your body, there are also medications that have the opposite effect.
- Change how your body handles fluids. Your kidneys are responsible for maintaining the fluid balance in your body. Certain medications can make your kidneys keep fluid and salt in your body, which can help with low blood pressure.
Complications/side effects of the treatment
The complications of either treatment depend on the exact medication or treatment you receive. Your healthcare provider can best explain the possible complications or side effects. That’s because they can consider your specific circumstances, including other health conditions, medications you take and more.
How to take care of myself?
If your healthcare provider diagnoses you with hypotension, they may do the following:
- Advise you to change your diet. Increasing your salt intake can often help increase your blood pressure.
- Teach you how to recognize and react to symptoms. A key way to help you avoid problems with hypotension is recognizing it. Your provider can help you recognize what low blood pressure feels like and how to react.
How soon after treatment will I feel better?
Depending on the cause of your hypotension, you may feel better as you receive treatment. In some cases, it may take longer — days or even weeks — for medication or other treatments to help you feel better consistently.
How can I reduce my risk of developing this or prevent it entirely?
It's usually not possible to reduce your risk of or prevent hypotension. The only exception is avoiding circumstances or actions that can lead to it, such as taking recreational drugs or supplements/herbal remedies that can lower your blood pressure.
Outlook / Prognosis
What can I expect if I have this condition?
If you have hypotension, what you can expect depends on what causes it and if you have symptoms. If you don’t have symptoms, it’s unlikely that hypotension will be a problem for you.
If you have symptoms, hypotension can interfere with your ability to stand up, care for yourself, cook, drive and do many other activities. That's why understanding the condition and following a healthcare provider's guidance are so important to minimizing this condition's impact on your life.
How long does hypotension last?
How long this condition lasts depends very much on what caused it. If you have hypotension because of normal aging, it will probably be a lifelong concern.
What’s the outlook for hypotension?
If you have low blood pressure but don’t have symptoms, this condition usually isn’t harmful and shouldn’t impact your life.
If you do have symptoms, the underlying cause is usually what determines the outlook for this condition. Your healthcare provider is the best person to tell you what to expect from this condition and what you can do to manage those effects.
Complications that can happen because of hypotension include:
- Falls and fall-related injury. These are the biggest risk with hypotension because it can cause dizziness and fainting. Falls can lead to broken bones, concussions and other serious or even life-threatening injuries. If you have hypotension, preventing falls should be one of your biggest priorities.
- Shock. When your blood pressure is low, that can affect your organs by reducing the amount of blood they get. That can cause organ damage or even shock (where your body starts to shut down because of limited blood flow and oxygen).
- Heart problems or stroke. Low blood pressure can cause your heart to try to compensate by pumping faster or harder. Over time, that can cause permanent heart damage and even heart failure. It can also cause problems like deep vein thrombosis and stroke because blood isn’t flowing like it should, causing clots to form.
How do I take care of myself?
If you have hypotension with symptoms, the best thing you can do is follow your healthcare provider's guidance on managing this condition. Their recommendations may include any of the following:
- Manage your diet. Following diet recommendations, especially how much salt you should have in your diet, can help avoid symptoms of hypotension.
- Take your medication. These can help you avoid the disruptive symptoms and effects of this condition.
- Dress up. Compression socks, which put light pressure on your legs and feet, can push blood upward and raise your blood pressure.
- Take it slow. Avoid standing up too quickly, especially with orthostatic hypotension. That can help you avoid the dizziness and fainting effects of hypotension.
- Have a seat. If you notice yourself feeling dizzy or lightheaded, sit down. Falling from standing height can put you at risk for severe or even catastrophic injuries from a fall, such as a broken hip, concussion, skull fracture or broken ribs.
When should I call or see my healthcare provider?
If you know you have hypotension, you should see your healthcare provider if you start to notice symptoms affecting your life or disrupting your usual routine and activities. If you don't know you have hypotension, you should see a healthcare provider if you have repeated dizziness or fainting episodes. This is especially important because those symptoms are possible with many other health conditions, some dangerous.
When should I go to ER?
If you have hypotension, you should go to the hospital for the following:
- Chest pain (angina).
- If you pass out or faint.
- If you fall because of lightheadedness and hit your head (especially if you’re taking any blood-thinning medications). You should also go to the hospital if you injure yourself because of a fall from passing out.
- If you have any symptoms of shock, such as feeling cold, sweaty, breathing fast, or you have a fast heart rate. You may also have a blue tint to the skin of your lips or under your fingernails.
A note from Cleveland Clinic
Hypotension is a condition that can have no symptoms, and many people don’t even know they have it. For others, it can cause symptoms that are unpleasant and even disruptive to your daily life and activities. If you suspect you have it, getting it diagnosed and treated is essential and can help you avoid falls and other complications. Fortunately, this condition is often treatable, and there are many things your healthcare provider can explain to you that can help you care for yourself.
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