Have you ever stood up quickly and felt a momentary wave of dizziness or lightheadedness come over you? That's called orthostatic hypotension, or low blood pressure that occurs when standing up after sitting or lying down, according to the Mayo Clinic. You also might hear it referred to as postural hypotension. It's not uncommon to experience a brief episode on occasion, for instance, due to dehydration or following a period of bed rest. Still, chronic orthostatic hypotension can be a sign of serious illness. Here, experts explain why orthostatic hypotension develops and what to do about it.
When you stand up from a chair or get up after lying down, gravity pulls some of the blood in your upper body down into your legs and your belly. That's normal. And your body has a built-in system to respond. "We have a sensor called the baroreceptor, which senses the drop in blood pressure, and it tells the brain to activate the autonomic nervous system, which tells the heart to increase the heart rate and the blood vessels to constrict," says Sheng-Peng Chen, M.D., the Burns and Allen chair of cardiology at Cedars-Sinai's Smidt Heart Institute in Los Angeles. Dr. Chen explains that the adrenal gland also contributes. It releases hormones such as norepinephrine that raise blood pressure and heart rate temporarily so that blood flow increases and your blood pressure returns to normal. "In that way," says Dr. Chen, "the body overrides the gravity effect."
With orthostatic hypotension, though, something goes wrong. Your body's means of stabilizing your blood pressure does not immediately go to work, and your blood pressure remains low. "One or more of the mechanisms fail, and it leads to a decline in blood pressure when people assume an upright position," says Minisha Kochar, M.D., a cardiologist at National Jewish Health in Denver, CO.
The result? "You have moments of poor perfusion or poor blood flow to the brain," says Joseph Daibes, D.O., a cardiologist at Northwell Lenox Hill Hospital in New York City. That's what causes the dizziness or, more dangerously, fainting.
Your blood pressure has two measurements. The larger number is called your systolic blood pressure. It's a measure of the pressure when your heart contracts, or squeezes, and pumps blood out to the rest of your body. The smaller number -- your diastolic blood pressure -- is a measure of the pressure when your heart relaxes and fills with blood. You have orthostatic hypotension if your systolic blood pressure drops by at least 20 milligrams of mercury (mm Hg) and/or your diastolic drops by at least 10 mm Hg within three minutes of standing up.
It's much more common in older people. Between 20% to 25% of people over 60 have orthostatic hypotension, according to a 2018 review in The Journals of Gerontology: Series A.
During an episode of orthostatic hypotension, the most common symptom is dizziness or lightheadedness, according to the Mayo Clinic. Our experts list several other symptoms that also can occur, including:
The symptom of greatest concern is fainting. That's because it leads to falls. "If someone falls, they can break a bone, especially older people," says Dr. Chen. Falls, says Dr. Daibes, also can cause serious head injuries.
A range of issues can trigger orthostatic hypertension, from underlying medical conditions to certain medications to lifestyle factors. In about 40% of cases, however, the cause remains unknown. Our experts explain some of the most common reasons you might experience orthostatic hypotension.
Dehydration
Dr. Chen says that most orthostatic hypotension can be explained by dehydration. When you have too little fluid in your body, you also have less blood circulating in your blood vessels, leading to low blood pressure, he explains. "When people have dehydration, they will not be able to increase the blood pressure [when they stand]," says Dr. Chen.
Certain conditions can make dehydration more likely. "If you're vomiting or have diarrhea, that can cause dehydration," says Dr. Kolchar.
Big Meals
Sometimes, particularly in older people, eating a large meal can lead to an episode of orthostatic hypotension. Why? Dr. Chen says that the more you eat, the more blood your gut will need in order to digest. "And that causes insufficient blood elsewhere," he explains. And, when you stand up, that blood remains in the gut rather than returning to the heart, leading to orthostatic hypotension.
Bed Rest
Staying in bed or resting for long periods, for instance, due to illness or recovering from surgery, can cause weakness and lead to an episode of orthostatic hypotension, according to the Mayo Clinic.
Neurological Problems
Your autonomic nervous system runs in the background, adjusting your heart rate and blood pressure to keep blood flowing normally. Certain diseases, such as Parkinson's disease and Lewy body dementia, can impair your nervous system's ability to regulate blood pressure, says Dr. Kochar.
Endocrine Disorders
Your endocrine system produces hormones that play important roles in many bodily functions, including regulating your blood pressure. According to the Mayo Clinic, problems that impact these hormones can cause orthostatic hypotension, including:
Heart Problems
Certain heart conditions can lead to low blood pressure and make it difficult for the heart to adjust the flow of blood when you stand up, according to the Mayo Clinic. These include:
Medications
Some medications can make orthostatic hypotension more likely. Our experts all say that blood pressure medications are a leading culprit. For example, beta blockers slow the heart rate and relax the blood vessels in order to lower blood pressure. However, this can make it harder for your heart to compensate for the drop in blood pressure that occurs when you stand up, according to a 2020 review in the journal Drugs and Aging. Other blood pressure medications, such as alpha blockers and nitrates, also may trigger orthostatic hypotension.
Other medications of concern include:
How your doctor will treat long-standing orthostatic hypotension depends on what's causing it. For example, if it's triggered by a medication you take, your doctor may be able to prescribe something else. "If I have a patient with orthostatic hypotension who takes a diuretic, I might change that medication," says Dr. Daibes. Common recommendations to prevent episodes of orthostatic hypotension include:
Staying Hydrated
Dehydration is the leading cause of orthostatic hypotension, and getting adequate fluids and salt will help. The salt, says Dr. Kochar, helps your body retain fluids. "The more salt and water you have in your body, the more volume of blood you will have, and that's going to reduce the symptoms," she explains.
But that gets complicated if you have both orthostatic hypotension and high blood pressure, because excess salt raises your BP. According to a 2023 study in JAMA, one in ten people with high blood pressure also have orthostatic hypotension. "We still have them on blood pressure medicines, but we tolerate slightly higher blood pressure in these patients," says Dr. Kochar.
Your doctor will advise you on managing your salt intake if you have high blood pressure.
Getting Up Slowly
When you wake up, don't immediately jump out of bed, says Dr. Daibes. Instead, rise slowly to a sitting position and remain perched on the edge of the bed for a minute. Then get to your feet, making sure you have something nearby to steady yourself. By moving at such a pace, you give your blood pressure more time to normalize. If you do feel dizzy when you stand up, sit back down again, says Dr. Daibes. This is important to remember whether you have chronic orthostatic hypotension, or you've recently had an illness or surgery that required you to rest for long periods, putting you at risk for the condition.
Exercising Before Standing
Dr. Chen says you can get the blood in your legs circulating better by doing brief exercises before you get out of bed or out of a chair. Try the following:
Dr. Kochar says that your doctor may recommend seeing a physical therapist. "They teach the patients different body movements to try to alleviate some of the symptoms," she says.
Wearing Compression Stockings and Abdominal Binders
Both will help to prevent blood from pooling in your legs and abdomen and improve the flow of blood back to your heart. Dr. Daibes recommends wearing these at all times except when sleeping.
Changing How You Eat
Dr. Chen recommends avoiding large meals, which can trigger orthostatic hypotension. Instead, he tells his patients to eat smaller, more frequent meals throughout the day. And he advises against drinking alcohol.
Medications for Orthostatic Hypotension
Dr. Kochar says that medications may be necessary if you still experience orthostatic hypotension despite trying the above remedies. These drugs medications include:
If you occasionally feel dizzy when you stand up, Dr Kochar says to play it safe and get checked out. "We don't want to just ignore even a first event because subsequent events could be more significant," she says. "Sometimes this can lead to people passing out."