Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when standing after sitting or lying down. Orthostatic hypotension can cause dizziness or lightheadedness and possibly fainting.

Orthostatic hypotension can be mild. Episodes might be brief. However, long-lasting orthostatic hypotension can signal more-serious problems. It's important to see a health care provider if you frequently feel lightheaded when standing up.

Occasional orthostatic hypotension is usually caused by something obvious, such as dehydration or lengthy bed rest. The condition is easily treated. Chronic orthostatic hypotension is usually a sign of another health problem, so treatment depends on the cause.

The most common symptom of orthostatic hypotension is lightheadedness or dizziness when standing 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

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

It's important to see a health care provider for frequent symptoms of orthostatic hypotension. Losing consciousness, even for just a few seconds, is serious. It requires seeing a provider right away.

Keep a record of your symptoms, when they occurred, how long they lasted and what you were doing at the time. Tell your care provider if symptoms occur at times that could be dangerous, such as while driving.

When standing from a sitting or lying position, gravity causes blood to collect in the legs and belly. Blood pressure drops because there's less blood flowing back to the heart.

Usually, special cells (baroreceptors) near the heart and neck arteries sense this lower blood pressure. The baroreceptors send signals to the brain. This tells the heart to beat faster and pump more blood, which evens out blood pressure. These cells also narrow the blood vessels and increase blood pressure.

Orthostatic hypotension occurs when something interrupts the body's process of dealing with the 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. Dehydration 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 the body from quickly pumping 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 that control 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 the body's ability to control blood pressure.
• 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 the heart and neck arteries that control blood pressure can slow as you age. It also can be harder for an aging heart to speed up to make up 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 can increase the 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.

• Certain diseases. Diseases that can increase the risk of low blood pressure include some heart conditions, such as heart valve problems, heart attack and heart failure. They also include certain nervous system disorders, such as Parkinson's disease. And they include diseases that cause nerve damage (neuropathy), such as diabetes.
• Heat exposure. Being in a hot environment can cause heavy sweating and possibly dehydration, which can lower blood pressure and trigger orthostatic hypotension.
• Bed rest. Staying in bed for a long time because of an illness or injury can cause weakness. This can lead to orthostatic hypotension.
• Alcohol. Drinking alcohol can increase the risk of orthostatic hypotension.

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

• Falls. Falling as a result of fainting is a common complication in people with orthostatic hypotension.
• Stroke. The swings in blood pressure from standing and sitting 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.

Treatment for orthostatic hypotension is directed at the cause rather than the low blood pressure itself. For example, if dehydration causes orthostatic hypotension, your health care provider may suggest lifestyle changes such as drinking more water. If a medication causes low blood pressure when standing, treatment may involve changing the dose or stopping the drug.

For mild orthostatic hypotension, one of the simplest treatments is to sit or lie back down immediately after feeling lightheaded upon standing. Often, symptoms will disappear. Sometimes, medications are needed to treat orthostatic hypotension.

Medications

If orthostatic hypotension doesn't improve with lifestyle changes, medications may be needed to increase blood pressure or blood volume. The type of medication depends on the type of orthostatic hypotension.

Drugs that may be used to treat orthostatic hypotension include midodrine (Orvaten), droxidopa (Northera), fludrocortisone or pyridostigmine (Mestinon, Regonol).

Talk to your health care provider about the risks and benefits of these drugs to determine which one is best for you.

You don't need to do anything special before having your blood pressure checked. But it's helpful to wear a short-sleeved shirt or a loose long-sleeved shirt that can be pushed up during the test. Doing so helps with fitting the blood pressure cuff around the arm properly.

Take your blood pressure regularly at home, and keep a log of your readings. Bring the log with you to your health care provider'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

When you make the appointment, ask if there's anything you need to do in advance, such as restrict your diet for a blood test. Plan to bring a family member or friend to your appointment, if possible, to help you remember all the information you're given.

Make a list of the following:

• Your symptoms, including any that may seem unrelated to low blood pressure, what triggers them and when they began.
• Key personal information, including a family history of low blood pressure and major stresses or recent life changes.

• All medications, vitamins or supplements you take, including doses. Or bring in the bottles of all the medications you take.

  Some medications — such as cold medicines, antidepressants, birth control pills and others — can affect your blood pressure. Don't stop taking any prescription medications that you think might affect your blood pressure without your care provider's advice.

• Questions to ask your care provider.

  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 provider about challenges you might face in getting started.

For orthostatic hypotension, questions to ask your health care provider 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?
• Do I need to follow any diet or activity restrictions?
• Are there any brochures available? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your health care provider 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?