Why faint when stand up

Some people feel dizziness more often than others, but it can happen to anyone — and it may be worth checking with your doctor. Potential causes of presyncope include: Orthostatic hypotension Also called postural hypotension, this is the head rush you sometimes feel when you stand up. Heart arrhythmia This condition also known as an abnormal heart rate is when your heart beats too fast, too slow or in a way that causes a sudden decrease in the blood supply to your brain.

Medications Medicines prescribed for pain, heart conditions and high blood pressure can affect your circulatory system and — you guessed it — feeling dizzy. Dehydration Not drinking enough fluids can cause nausea, weakness, dizziness, low blood pressure and fainting. Anemia Anemia is a lack of healthy red blood cells or hemoglobin in your blood, which carry oxygen to your organs — including your brain.

Autonomic neuropathy This nerve disease disrupts electrical signals between your brain and heart, blood vessels and sweat glands. Stress and panic attacks Ever had an anxiety attack?

What to do if you feel faint When you get that lightheaded feeling, lie down or sit down and place your head between your knees. You stand up suddenly and are met with a feeling of wooziness. In some cases, your vision gets splotchy, or you have to brace yourself until the dizziness passes—which it always does in a matter of seconds. Experts have a name for this fleeting condition: initial orthostatic hypotension OH.

It may help to think of your body and the blood circulating through it as a half-full water bottle. When the water bottle is lying on its side, the liquid inside is evenly dispersed.

But flip the water bottle up, and all the liquid slides to the bottom. Something similar tries to happen whenever you stand up. Rebecca Gottesman, a professor of neurology at Johns Hopkins University. She points out that young women and super-fit people—like those who train for and compete in endurance competitions—tend to have lower blood pressure scores, and so may be more susceptible to OH symptoms. Dehydration could also raise your risks. Some medications, as well as pregnancy, are also associated with OH, Gottesman says.

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:. 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. Persistent orthostatic hypotension can cause serious complications, especially in older adults. These include:. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. The part of the nervous system responsible for this compensation is the autonomic nervous system Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing.

Many disorders can cause problems with blood pressure regulation and lead to dizziness when standing up. Categories of causes include. The most common causes of dizziness when standing up that has been present for a long time chronic include.

People who become dizzy or light-headed when standing up often recover quickly when they sit down and then slowly stand again. However, it is usually important to determine what is causing the dizziness. The following information can help people decide when to see a doctor and help them know what to expect during the evaluation. In people who become dizzy or light-headed when standing up, certain symptoms and characteristics are cause for concern.

They include. People who have warning signs should see a doctor right away. Other people who have frequent or ongoing episodes of dizziness upon standing should see a doctor when practical.

Typically a delay of a week or so is not harmful. People who have only an occasional episode of dizziness upon standing should call their doctor. The doctor will decide whether and how quickly to see the person depending on the other symptoms and medical history.

The doctor first asks questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the dizziness and the tests that may need to be done. Whether the person has experienced conditions that are known to cause dizziness such as bed rest or fluid loss. Whether the person has a disorder such as diabetes, Parkinson disease, or a cancer that may cause dizziness. The doctor then does a physical examination.

The person lies down for 5 minutes, and then the doctor measures the blood pressure and heart rate. Blood pressure and heart rate are measured again after the person stands or sits up for 1 minute and again after standing or sitting for 3 minutes.

The doctor may do a digital rectal examination to see whether the person might have some bleeding in the digestive tract. A neurologic examination to test strength, sensation, reflexes, balance, and gait is important. The most common causes of sudden dizziness—drugs, bed rest, and decreased blood volume—are usually obvious.