If your heart suddenly pounds or speeds up when you stand, there are several possible explanations. Sometimes it is the body’s normal response to gravity. Other causes include dehydration, anemia, low blood pressure, medicines and POTS. The pattern of your heart rate, blood pressure and symptoms helps doctors tell the difference.
Family Physician / General Practitioner
Cardiologist
It is normal for your heart rate to rise a little when you stand up. What deserves attention is a heartbeat that becomes much faster and stays faster while you are upright, especially if you also feel dizzy, weak, shaky, lightheaded or close to fainting.
POTS is one possible explanation, but a fast heart rate when standing does not automatically mean you have POTS.
Doctors also look for dehydration, anemia, blood loss, low blood pressure, thyroid problems, medicines and other causes before diagnosing POTS.
When to Get Urgent Medical Help
Seek urgent or emergency care if the racing or pounding heartbeat occurs with:
- significant chest pain or pressure;
- severe or sudden shortness of breath;
- fainting or collapse;
- severe dizziness or inability to stay upright;
- a sustained very fast or markedly irregular heartbeat while you feel seriously unwell;
- confusion or reduced responsiveness;
- significant bleeding;
- severe dehydration; or
- rapidly worsening symptoms.
Do not assume fainting, chest pain or severe breathlessness is “just POTS.”
What Normally Happens When You Stand Up?
When you stand, gravity pulls some blood toward your legs and lower abdomen.
For a moment, slightly less blood returns to your heart.
Your body quickly responds by:
- tightening blood vessels;
- increasing heart rate slightly;
- maintaining blood pressure; and
- keeping enough blood flowing to the brain.
This is normal.
The concern is when the heart rate rises excessively and remains elevated while standing, particularly when the change repeatedly causes symptoms.
When Could Heart Racing After Standing Be POTS?
POTS stands for Postural Orthostatic Tachycardia Syndrome.
In simple terms, the body has difficulty adjusting its circulation when you are upright.
The heart speeds up more than expected to help maintain blood flow.
POTS becomes more likely when the racing heartbeat is accompanied by several symptoms that appear mainly while standing or sitting upright.
Heart racing
The pulse rises substantially after standing and remains elevated rather than quickly settling.
Dizziness
You may become lightheaded or feel as though you need to sit or lie down.
Weakness or shakiness
Standing may cause trembling, weakness or a feeling that your legs will not support you.
Brain fog
Concentration or clear thinking can become more difficult while upright.
Exercise intolerance
Ordinary activity may produce disproportionate fatigue or a racing heart.
Feeling better when lying down
A particularly useful clue is that symptoms often improve after returning to a lying position.
The Pattern Matters More Than One Heart-Rate Reading
POTS is a syndrome — a combination of symptoms and an abnormal heart-rate response to standing. It cannot be diagnosed from one smartwatch number.
How Do Doctors Diagnose POTS?
Doctors look for several findings together.
| What doctors look for | What it means |
|---|---|
| Heart rate rises when standing | At least 30 beats per minute in adults within 10 minutes of standing. |
| Adolescent threshold | At least 40 beats per minute for people ages 12–19. |
| Symptoms while upright | Symptoms such as palpitations, dizziness, weakness or brain fog become worse when standing. |
| Symptoms improve when lying down | Returning to a horizontal position usually makes orthostatic symptoms better. |
| The problem is persistent | The symptom pattern is chronic, generally lasting at least three months. |
| No classic orthostatic hypotension | The symptoms are not explained by the characteristic large blood-pressure drop that defines orthostatic hypotension. |
| No better explanation | Conditions such as dehydration, anemia, blood loss, fever, hyperthyroidism or medication effects must be considered. |
A 30-Beat Increase Does Not Automatically Mean POTS
Imagine your heart rate rises from 70 to 102 after you stand.
That is an increase of 32 beats per minute.
It meets the numerical adult threshold, but if you are dehydrated after vomiting or have recently lost blood, another condition may explain the fast heart rate. That would not automatically be diagnosed as POTS.
What Else Can Cause Your Heart to Race When You Stand?
POTS is only one possibility.
Dehydration
Too little circulating fluid makes it harder to maintain blood flow when standing. The heart may compensate by beating faster.
Iron-deficiency anemia
Low hemoglobin can cause a faster heartbeat, weakness, dizziness, fatigue and shortness of breath.
Recent blood loss
Blood loss reduces circulating volume and can cause both a rapid pulse and dizziness after standing.
Low blood pressure
Some people develop an excessive drop in blood pressure when they stand. This is called orthostatic hypotension.
Medicines
Diuretics, blood-pressure medicines, stimulants and some other drugs can affect heart rate, blood pressure or fluid volume.
Thyroid disease
An overactive thyroid can cause persistent tachycardia, sweating, tremor and palpitations.
Fever or illness
Fever and infection can increase heart rate and may also cause dehydration.
A heart arrhythmia
SVT, atrial fibrillation or another rhythm problem can also cause racing or irregular heartbeats.
Read more about dehydration and heart palpitations and low iron, anemia and heart palpitations .
POTS or Low Blood Pressure: What Is the Difference?
Both conditions can make you dizzy when you stand, but they are not the same.
| POTS | Orthostatic Hypotension | |
|---|---|---|
| Main change | Heart rate rises excessively. | Blood pressure falls excessively. |
| Heart rate | Sustained increase of at least 30 bpm in adults or 40 bpm in adolescents. | May rise as the body tries to compensate. |
| Blood pressure | Classic orthostatic hypotension is absent. | Systolic pressure falls at least 20 mm Hg or diastolic pressure falls at least 10 mm Hg within three minutes. |
| Common symptoms | Palpitations, dizziness, weakness, brain fog, fatigue and exercise intolerance. | Dizziness, blurred vision, weakness, lightheadedness and fainting. |
Heart rate alone does not tell the full story.
Is POTS a Heart Arrhythmia?
No.
In POTS, the heart usually remains in sinus rhythm — the normal electrical rhythm generated by the heart’s natural pacemaker.
The problem is that the sinus rate becomes excessively fast when upright.
POTS and SVT Are Different
POTS usually causes the heart rate to rise in relation to standing.
SVT often begins very suddenly, produces a rapid rhythm and may also stop abruptly.
If racing episodes occur regardless of posture or begin and end suddenly, your clinician may need to consider an arrhythmia rather than assuming every episode is POTS.
Can You Have POTS With a Normal ECG?
Yes.
Someone with POTS may have a completely normal ECG while resting or lying down.
POTS is identified mainly by:
- what happens to heart rate when you become upright;
- what happens to blood pressure;
- the symptoms you experience; and
- whether another condition explains the problem.
A normal resting ECG therefore does not rule out POTS.
See our guide to heart palpitations despite a normal ECG .
How Do Doctors Test for POTS?
Heart rate and blood pressure while lying and standing
The simplest assessment compares heart rate and blood pressure after resting horizontally and then during upright posture.
10-minute standing test
Heart rate, blood pressure and symptoms are measured during up to 10 minutes of standing.
Tilt-table test
A tilt-table test places you on a table that moves from horizontal toward an upright position while clinicians continuously monitor your response.
Not everyone suspected of having POTS needs a tilt-table test.
Do Not Force Yourself to Stand if You Feel You Are About to Faint
Home heart-rate readings may be useful information, but preventing a fall is more important than trying to complete a 10-minute self-test.
ECG
An ECG helps determine whether the fast heartbeat is sinus tachycardia or another rhythm.
Holter or longer heart monitor
Rhythm monitoring may be appropriate if episodes are unusual, very rapid, irregular or not consistently related to standing.
Blood tests
Your clinician may check for:
- anemia;
- iron deficiency;
- thyroid disease;
- electrolyte problems;
- kidney problems;
- blood glucose abnormalities; or
- other conditions suggested by your symptoms.
Can an Apple Watch or Smartwatch Diagnose POTS?
No.
A smartwatch can show that your heart rate rises when you stand, and that information may be useful to your clinician.
But the watch usually cannot tell:
- whether your blood pressure fell;
- whether you are dehydrated;
- whether you have anemia;
- whether your symptoms meet the chronic POTS pattern; or
- whether another medical condition explains the tachycardia.
What Can Help if You Have POTS?
Treatment depends on the individual and should focus on both symptoms and the underlying circulatory problem.
Fluids
Some patients benefit from increasing fluid intake to support circulating blood volume.
Salt
Some people with confirmed POTS are advised to increase sodium intake.
Do Not Start a High-Salt Diet Just Because You Suspect POTS
Extra sodium may be inappropriate if you have high blood pressure, kidney disease, heart failure or another condition. Fluid and sodium recommendations should be individualized.
Compression garments
Compression garments may reduce blood pooling in the legs and abdomen in selected patients.
Gradual physical reconditioning
A structured exercise program can improve circulation and physical conditioning over time.
Some patients initially tolerate seated or recumbent exercise better than upright exercise.
Medication
Some patients need medication to reduce excessive heart rate or support circulation.
There is no single medication that is right for every patient with POTS, and current therapies are individualized according to heart rate, blood pressure and symptoms.
Do Not Self-Treat POTS With Heart Medication
Do not take extra beta-blockers or another person’s heart or blood-pressure medicine because your pulse rises when you stand.
What Should You Do if You Feel Faint When You Stand?
If there are no emergency warning signs:
- Sit or lie down somewhere safe.
- Do not continue walking if you feel close to fainting.
- Allow the dizziness to settle before trying to stand again.
- Stand up more gradually the next time.
- Record the heart rate and symptoms if this can be done safely.
- Notice whether lying down clearly improves the symptoms.
- Arrange medical assessment if the pattern keeps happening.
If your vision starts going dark or you feel that you may pass out, do not remain standing merely to see how high your heart rate becomes.
Dr. Albana’s Note
If a patient tells me, “My heart races every time I stand,” I do not immediately diagnose POTS. I first ask what happens to the blood pressure, whether there is dizziness or near-fainting, and whether the symptoms improve when the patient lies down. I also look for common explanations such as dehydration, anemia, blood loss, thyroid disease and medication effects. A large rise in heart rate is an important clue, but POTS is a pattern of chronic upright symptoms — not simply one high number on a smartwatch.
When Should You See a Doctor?
Make a medical appointment if:
- your heart repeatedly races when you stand;
- you frequently become dizzy or lightheaded when upright;
- you regularly need to sit or lie down to feel better;
- you experience recurrent near-fainting;
- you have persistent brain fog or unusual fatigue;
- standing or walking has become difficult;
- your symptoms have lasted for weeks or months;
- you have known anemia, thyroid disease or low blood pressure;
- the problem began after illness, surgery, pregnancy or a medication change;
- the heartbeat feels irregular; or
- the symptoms are interfering with work, school, exercise or daily life.
For broader guidance, see when to worry about heart palpitations .
Most Asked Questions
Why does my heart race when I stand up?
Your heart rate normally rises slightly when you stand. A larger increase may occur with dehydration, anemia, blood loss, low blood pressure, medication effects, POTS or another condition.
How much should heart rate increase when standing?
There is normal individual variation. For POTS assessment, doctors specifically look for a sustained increase of at least 30 beats per minute in adults or 40 beats per minute in adolescents within 10 minutes upright, together with the other diagnostic criteria.
If my heart rate rises 30 bpm, do I have POTS?
Not necessarily. The rise must occur with the characteristic chronic upright symptoms, and dehydration, anemia, blood loss, orthostatic hypotension and other causes must be excluded.
Can dehydration look like POTS?
Yes. Dehydration reduces circulating blood volume and can cause both tachycardia and dizziness when standing. Acute dehydration must be considered before diagnosing POTS.
Can anemia cause a racing heart when standing?
Yes. Anemia can cause a faster heartbeat, weakness, dizziness, breathlessness and exercise intolerance and may resemble some POTS symptoms.
Does POTS cause low blood pressure?
Not necessarily. Some people with POTS maintain normal blood pressure, and some may have higher blood pressure when standing. Classic orthostatic hypotension is a different condition.
Is POTS an arrhythmia?
No. POTS usually involves an excessive increase in normal sinus heart rate when upright. It is different from electrical arrhythmias such as atrial fibrillation or SVT.
Can POTS happen with a normal ECG?
Yes. The resting ECG can be completely normal because POTS is identified mainly from the heart-rate and symptom response to upright posture.
Can a smartwatch diagnose POTS?
No. A smartwatch can provide useful heart-rate information but cannot by itself evaluate blood pressure, exclude other causes or confirm all of the diagnostic criteria.
When should a racing heart after standing worry me?
Seek urgent care for significant chest pain, severe shortness of breath, collapse, severe dizziness, prolonged fainting, significant bleeding or a sustained very fast or markedly irregular heartbeat while you feel seriously unwell.
Related Heart Palpitation Guides
Medical References
- Johns Hopkins Medicine. Postural Orthostatic Tachycardia Syndrome (POTS).
- American College of Cardiology / American Heart Association / Heart Rhythm Society. Guideline for the Evaluation and Management of Patients With Syncope.
- National Institutes of Health Expert Consensus Meeting. Postural Orthostatic Tachycardia Syndrome: State of the Science and Clinical Care.
- JACC: Advances. Clinical Research on Postural Orthostatic Tachycardia Syndrome. 2026.
- American Heart Association. Orthostatic Hypotension in Adults: Scientific Statement.
About the Medical Team
Dr. Albana Greca, MBBS, MMedSc
Family Physician / General Practitioner
Dr. Albana Greca has more than 20 years of experience in primary care, general medicine, chronic disease management, prevention and patient education.
Dr. Benard Shehu, MBBS, MS
Cardiologist
Dr. Benard Shehu has more than 19 years of cardiovascular experience, including clinical experience relevant to heart rhythm disorders and cardiovascular disease.