Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even cause you to faint.

Orthostatic hypotension may be mild, and episodes can last for less than a few minutes. However, long-lasting orthostatic hypotension can signal more-serious problems, so it's important to see a doctor if you frequently feel lightheaded when standing up.

Occasional (acute) orthostatic hypotension is usually caused by something obvious, such as dehydration or lengthy bed rest, and is easily treated. Chronic orthostatic hypotension is usually a sign of another health problem, so treatment varies.

The most common symptom is lightheadedness or dizziness when you stand up after sitting or lying down. Symptoms usually last less than a few minutes.

Orthostatic hypotension signs and symptoms include:

• Lightheadedness or dizziness upon standing
• Blurry vision
• Weakness
• Fainting (syncope)
• Confusion
• Nausea

When to see a doctor

Occasional dizziness or lightheadedness may be fairly minor — triggered by mild dehydration, low blood sugar or overheating. Dizziness or lightheadedness may also happen when you stand after sitting for a long time. If these symptoms happen only occasionally, there's likely no cause for concern.

It's important to see your doctor if you have frequent symptoms of orthostatic hypotension because they can signal serious problems. It's even more urgent to see a doctor if you lose consciousness, even for just a few seconds.

Keep a record of your symptoms, when they occurred, how long they lasted and what you were doing at the time. If these occur at dangerous times, such as while driving, discuss this with your doctor.

When you stand up, gravity causes blood to pool in your legs and abdomen. This decreases blood pressure because there's less blood circulating back to your heart.

Normally, special cells (baroreceptors) near your heart and neck arteries sense this lower blood pressure. The baroreceptors send signals to centers in your brain, which signals your heart to beat faster and pump more blood, which stabilizes blood pressure. These cells also narrow the blood vessels and increase blood pressure.

Orthostatic hypotension occurs when something interrupts the body's natural process of counteracting low blood pressure. Many conditions can cause orthostatic hypotension, including:

• Dehydration. Fever, vomiting, not drinking enough fluids, severe diarrhea and strenuous exercise with a lot of sweating can all lead to dehydration, which decreases blood volume. Mild dehydration can cause symptoms of orthostatic hypotension, such as weakness, dizziness and fatigue.
• Heart problems. Some heart conditions that can lead to low blood pressure include extremely low heart rate (bradycardia), heart valve problems, heart attack and heart failure. These conditions prevent your body from responding rapidly enough to pump more blood when standing up.
• Endocrine problems. Thyroid conditions, adrenal insufficiency (Addison's disease) and low blood sugar (hypoglycemia) can cause orthostatic hypotension. So can diabetes — which can damage the nerves that help send signals regulating blood pressure.
• Nervous system disorders. Some nervous system disorders, such as Parkinson's disease, multiple system atrophy, Lewy body dementia, pure autonomic failure and amyloidosis, can disrupt your body's normal blood pressure regulation system.
• Eating meals. Some people have low blood pressure after eating meals (postprandial hypotension). This condition is more common in older adults.

The risk factors for orthostatic hypotension include:

• Age. Orthostatic hypotension is common in those who are age 65 and older. Special cells (baroreceptors) near your heart and neck arteries that regulate blood pressure can slow as you age. It also may be harder for an aging heart to speed up and compensate for drops in blood pressure.

• Medications. These include medications used to treat high blood pressure or heart disease, such as diuretics, alpha blockers, beta blockers, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors and nitrates.

  Other medications that may increase your risk of orthostatic hypotension include medications used to treat Parkinson's disease, certain antidepressants, certain antipsychotics, muscle relaxants, medications to treat erectile dysfunction and narcotics.

  Using medications that treat high blood pressure with other prescription and over-the-counter medications may cause low blood pressure.

• Certain diseases. Some heart conditions, such as heart valve problems, heart attack and heart failure; certain nervous system disorders, such as Parkinson's disease; and diseases that cause nerve damage (neuropathy), such as diabetes, increase the risk of low blood pressure.
• Heat exposure. Being in a hot environment can cause heavy sweating and possibly dehydration, which can lower your blood pressure and trigger orthostatic hypotension.
• Bed rest. If you have to stay in bed a long time because of an illness, you may become weak. When you try to stand up, you may have orthostatic hypotension.
• Pregnancy. Because your circulatory system expands rapidly during pregnancy, blood pressure is likely to drop. This is normal, and blood pressure usually returns to your pre-pregnancy level after you've given birth.
• Alcohol. Drinking alcohol can increase your risk of orthostatic hypotension.

Persistent orthostatic hypotension can cause serious complications, especially in older adults. These include:

• Falls. Falling down as a result of fainting is a common complication in people with orthostatic hypotension.
• Stroke. The swings in blood pressure when you stand and sit as a result of orthostatic hypotension can be a risk factor for stroke due to the reduced blood supply to the brain.
• Cardiovascular diseases. Orthostatic hypotension can be a risk factor for cardiovascular diseases and complications, such as chest pain, heart failure or heart rhythm problems.

Your doctor's goal in evaluating orthostatic hypotension is to find the cause and determine appropriate treatment. The cause isn't always known.

Your doctor may review your medical history and your symptoms and conduct a physical examination to help diagnose your condition.

Your doctor also may recommend one or more of the following:

• Blood pressure monitoring. Your doctor will measure your blood pressure both while you're sitting and while you're standing and will compare the measurements. Your doctor will diagnose orthostatic hypotension if you have a drop of 20 millimeters of mercury (mm Hg) in your systolic blood pressure or a drop of 10 mm Hg in your diastolic blood pressure within two to five minutes of standing, or if standing causes signs and symptoms.
• Blood tests. These can provide information about your overall health, including low blood sugar (hypoglycemia) or low red blood cell levels (anemia), both of which can cause low blood pressure.

• Electrocardiogram (ECG or EKG). This noninvasive test detects irregularities in your heart rhythm or heart structure and problems with the supply of blood and oxygen to your heart muscle.

  During this test, soft, sticky patches (electrodes) are attached to the skin of your chest, arms and legs. The patches detect your heart's electrical signals while a machine records them on graph paper or displays them on a screen.

  Sometimes, heart rhythm abnormalities come and go, and an ECG won't find problems. If this happens, you may be asked to wear a 24-hour Holter monitor to record your heart's electrical activity as you go about your daily routine.

• Echocardiogram. In this noninvasive exam, sound waves are used to produce a video image of your heart. Sound waves are directed at your heart from a wandlike device (transducer) that's held on your chest.

  The sound waves that bounce off your heart are reflected through your chest wall and processed electronically to provide video images of your heart in motion to detect structural heart disease.

• Stress test. A stress test is performed while you're exercising, such as walking on a treadmill. Or you may be given medication to make your heart work harder if you're unable to exercise. Your heart is then monitored with electrocardiography, echocardiography or other tests.
• Tilt table test. A tilt table test evaluates how your body reacts to changes in position. You'll lie on a flat table that tilts to raise the upper part of your body, which simulates the movement from lying down to standing. Your blood pressure is taken frequently as the table is tilted.
• Valsalva maneuver. This noninvasive test checks the functioning of your autonomic nervous system by analyzing your heart rate and blood pressure after several cycles of a type of deep breathing: You breathe in deeply and push the air out through your lips, as if you were trying to blow up a stiff balloon.

The goal of treatment for orthostatic hypotension is to restore normal blood pressure. That usually involves increasing blood volume, reducing the pooling of blood in your lower legs and helping blood vessels to push blood throughout your body.

Treatment often addresses the cause — dehydration or heart failure, for example — rather than the low blood pressure itself.

For mild orthostatic hypotension, one of the simplest treatments is to sit or lie back down immediately after feeling lightheaded upon standing. Your symptoms should disappear.

When low blood pressure is caused by medications, treatment usually involves changing the dose of the medication or stopping it.

Orthostatic hypotension treatments include:

• Lifestyle changes. Your doctor may suggest several lifestyle changes, including drinking enough water; drinking little to no alcohol; avoiding overheating; elevating the head of your bed; avoiding crossing your legs when sitting; and standing up slowly. Then pause briefly to be sure it's ok for you to start walking.

If you don't also have high blood pressure, your doctor might suggest increasing the amount of salt in your diet. If your blood pressure drops after eating, your doctor may recommend small, low-carbohydrate meals.

• Compression stockings. Compression stockings and garments or abdominal binders may help reduce the pooling of blood in your legs and reduce the symptoms of orthostatic hypotension.

• Medications. A few drugs are used to treat orthostatic hypotension, including midodrine (Orvaten) and droxidopa (Northera). Side effects of midodrine can include retaining urine, tingling or itchy scalp, and goose-bumps. Side effects of droxidopa can include nausea, headache and bladder pain. With either drug, avoid lying flat for four hours after taking it to reduce the risk of high blood pressure while lying down.

  Fludrocortisone is often used to help increase the amount of fluid in your blood, which raises blood pressure, but it can have serious side effects. If you take fludrocortisone, your doctor will monitor you for side effects.

  Another medication is pyridostigmine (Mestinon, Regonol). This drug might be more effective combined with midodrine. Side effects can include abdominal cramps, nausea and diarrhea.

Some simple steps help manage or prevent orthostatic hypotension. Your doctor may give you several suggestions, including:

• Increase salt in your diet. This must be done carefully and only after discussing it with your doctor. Too much salt can cause your blood pressure to increase beyond a healthy level, creating new health risks.
• Eat small meals. If your blood pressure drops after eating, your doctor may recommend small, low-carbohydrate meals.
• Ask about vitamin supplements. Both anemia and vitamin B-12 deficiency can affect blood flow and worsen symptoms of orthostatic hypotension, so iron and vitamin supplements might be helpful for you if you're deficient.
• Get plenty of fluids. Keeping hydrated helps prevent symptoms of low blood pressure. Drink plenty of water before long periods of standing, or any activities that tend to trigger your symptoms.
• Avoid alcohol. Alcohol can worsen orthostatic hypotension, so limit or avoid it completely.
• Exercise. Regular cardiovascular and strengthening exercises may help reduce symptoms of orthostatic hypotension. Avoid exercising in very hot, humid weather. Stretch and flex your calf muscles before sitting up. If symptoms strike, squeeze your thighs together as well as your abdominal and buttock muscles. Squat, march in place or rise onto your tiptoes.
• Avoid bending at the waist. If you drop something on the floor, squat with your knees to recover it.
• Wear waist-high compression stockings. These may help improve blood flow and reduce the symptoms of orthostatic hypotension. Wear them during the day, but take them off for bed and anytime you lie down.
• Get up slowly. You may be able to reduce the dizziness and lightheadedness that occur with orthostatic hypotension by moving slowly from a lying to standing position. Also, when getting out of bed, sit on the edge of your bed for a minute before standing.
• Raise your head in bed. Sleeping with the head of your bed slightly raised can help fight the effects of gravity.
• Move your legs while standing. If you begin to get symptoms while standing, cross your thighs in a scissors fashion and squeeze, or put one foot on a ledge or chair and lean as far forward as possible. These maneuvers encourage blood to flow from your legs to your heart.

No special preparations are necessary to have your blood pressure checked. But it's helpful if you wear a short-sleeved shirt or a loosefitting long-sleeved shirt that can be pushed up during your evaluation so that the blood pressure cuff can fit around your arm properly.

Take your blood pressure regularly at home, and keep a log of your readings. Bring the log with you to your doctor's appointment.

Take your blood pressure first thing in the morning. Lie down for the first reading. Complete taking your blood pressure, then wait one minute. Stand and take the second reading.

Also take your blood pressure at these times:

• After you eat
• When your symptoms are least severe
• When your symptoms are most severe
• When you take your blood pressure medications
• One hour after you take your blood pressure medications

Here's some information to help you get ready for your appointment.

What you can do

• Be aware of any pre-appointment restrictions. When you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet for a blood test.
• Write down any symptoms you have, including any that may seem unrelated to low blood pressure, what triggers them and when they began.
• Write down key personal information, including a family history of low blood pressure and any major stresses or recent life changes.
• Make a list or bring bottles of all medications, vitamins or supplements you take because some medications — such as over-the-counter cold medicines, antidepressants, birth control pills and others — can affect your blood pressure. Don't stop taking any prescription medications that you think may affect your blood pressure without your doctor's advice.
• Take a family member or friend along, if possible. Sometimes it can be difficult to remember all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Be prepared to discuss your diet and exercise habits, especially the amount of salt in your diet. If you don't already follow a diet or exercise routine, be ready to talk to your doctor about any challenges you might face in getting started.
• Write down questions to ask your doctor.

For orthostatic hypotension, questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• Could my medications be a factor?
• What are other possible causes for my symptoms or condition?
• What tests will I need?
• What's the most appropriate treatment?
• How often should I be screened for low blood pressure? Should I measure it at home?
• I have other health conditions. How can I best manage these conditions together?
• Are there any dietary or activity restrictions that I need to follow?
• Are there any brochures or other printed material that I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your doctor will likely ask you questions, such as:

• How often do you have symptoms?
• How severe are your symptoms?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?
• Do you ever temporarily stop taking your medications because of side effects or because of the expense?