Getting dizzy when you stand up is usually caused by a temporary drop in blood pressure as gravity pulls blood toward your legs. In most cases, your body corrects this within seconds, but when that correction is too slow or too weak, your brain briefly doesn’t get enough blood flow, and you feel lightheaded, woozy, or like you might faint. The medical term for this is orthostatic hypotension, and it affects about 5% of middle-aged adults and roughly 20% of people over 60.
What Happens Inside Your Body
When you’re sitting or lying down, blood is distributed relatively evenly. The moment you stand, gravity pulls about 300 to 800 milliliters of blood into your legs and abdomen. Your body has a built-in correction system for this: pressure sensors called baroreceptors, located in your major arteries, detect the sudden drop in pressure against your artery walls. They send a signal to your brain, which responds by tightening your blood vessels, increasing your heart rate, and making your heart pump more forcefully. All of this happens in a few heartbeats.
Dizziness on standing means something in that chain isn’t working fast enough. Maybe your blood vessels are slow to tighten, or your heart doesn’t speed up quickly enough, or you simply don’t have enough fluid in your bloodstream to maintain pressure in the first place. The result is the same: a brief moment where your brain isn’t getting the blood flow it needs, and you feel it as lightheadedness, dimming vision, or a sense that you’re about to pass out.
Lightheadedness vs. Vertigo
It’s worth distinguishing what you’re actually feeling. The dizziness from standing up is typically lightheadedness: a woozy, off-balance sensation where you feel like you might fall if you don’t sit back down. Vertigo is different. Vertigo is a spinning sensation, where the room seems to rotate around you or you feel like you’re moving when you’re not. Vertigo usually involves the inner ear or specific parts of the brain and isn’t triggered by standing up in the way blood pressure dizziness is. If you feel a spinning sensation that lasts minutes or longer, that points to a different set of causes than what’s discussed here.
The Most Common Causes
Dehydration is the single most common trigger. When you haven’t had enough water, or you’ve lost fluid through sweating, illness, or alcohol, your blood volume drops. Less blood means less pressure, and your body has a harder time compensating when you stand. This is why many people notice this dizziness more on hot days, after exercise, or during a hangover.
Medications are another major factor. Blood pressure drugs, particularly alpha blockers, beta blockers, and diuretics (especially loop diuretics), directly interfere with the mechanisms your body uses to adjust to position changes. Tricyclic antidepressants, antipsychotics, and nitrates also commonly cause dizziness on standing. If you started a new medication and began noticing this symptom, the timing is probably not a coincidence.
Prolonged bed rest or inactivity can decondition your cardiovascular system. Your body essentially “forgets” how to make quick adjustments to position changes. This is common after surgery, long illness, or extended periods of sitting. Age plays a role too, because the baroreceptor reflex naturally slows as you get older, which is why one in five older adults deals with this regularly.
Other contributors include low blood sugar, anemia, pregnancy, and conditions that affect the nervous system like diabetes or Parkinson’s disease. In these cases, the nerves that control blood vessel tightening may be damaged, making the automatic correction permanently less effective.
When It Might Be POTS
If your dizziness on standing comes with a racing heart rather than (or in addition to) low blood pressure, you may be dealing with postural orthostatic tachycardia syndrome, or POTS. The hallmark of POTS is a heart rate increase of at least 30 beats per minute within 10 minutes of standing (40 beats per minute for adolescents), without a major drop in blood pressure. People with POTS often feel not just dizzy but also fatigued, brain-foggy, and shaky upon standing, and symptoms can be severe enough to interfere with daily life.
POTS is most common in women between 15 and 50 and can be triggered by viral infections, surgery, or other physical stressors. It’s frequently misdiagnosed or dismissed, so if your symptoms are persistent and seem out of proportion to simple dehydration, it’s worth bringing up specifically with your doctor.
How It’s Diagnosed
Clinically, orthostatic hypotension is defined as a drop of at least 20 points in systolic blood pressure (the top number) or 10 points in diastolic pressure (the bottom number) within two to five minutes of standing. Your doctor can check this with a simple test: measuring your blood pressure while you’re lying down, then again after you stand. A tilt table test, where you’re strapped to a table that gradually tilts upright while your blood pressure and heart rate are monitored, provides a more controlled measurement and is also used to diagnose POTS.
Practical Ways to Manage It
The most effective intervention is also the simplest: drink more water. Increasing your fluid intake helps maintain blood volume, giving your body more to work with when you change positions. Adding extra salt to your diet can also help, because sodium encourages your body to retain fluid. This is one of the few situations where a higher-salt diet is actually beneficial, though it’s not appropriate for everyone, particularly people with heart failure or kidney disease.
How you stand up matters. Rising slowly, especially from lying down, gives your baroreceptors time to detect the change and trigger a response. Try sitting on the edge of the bed for 15 to 30 seconds before standing, and flex your calf muscles a few times before you get up. Crossing your legs while standing or clenching your thigh muscles can also help push blood back up toward your heart.
Compression stockings that reach at least thigh height can reduce the amount of blood that pools in your legs. They’re not glamorous, but for people with frequent symptoms, they make a noticeable difference. Eating smaller, more frequent meals can also help, because digestion diverts blood to your gut, which can worsen symptoms after large meals.
If a medication is the culprit, your doctor may adjust the dose or switch you to a different drug. Never stop a prescribed medication on your own because of dizziness, but do bring up the symptom at your next appointment so the two of you can weigh options.
Signs That Need Prompt Attention
Occasional lightheadedness when you jump out of bed too fast is common and usually harmless. But if it’s happening frequently, getting worse, or if you’ve actually fainted, even briefly, that warrants a medical evaluation. Losing consciousness, even for a few seconds, is serious because of the fall risk alone. You should also mention it to a doctor if the dizziness happens in situations where it could be dangerous, like while driving, or if it’s accompanied by chest pain, significant shortness of breath, or neurological symptoms like slurred speech or weakness on one side of your body.