Why Do I Feel Dizzy and My Heart Race When I Stand Up?

Written and medically reviewed by Jeehyun Ham, M.D.

You stand up from a chair or get out of bed, and for a moment you feel lightheaded. Your vision may seem less clear, your body may feel unsteady, and your heart may begin beating faster.

This can happen because standing requires the body to make rapid adjustments in blood pressure, blood flow, and heart rate.

The autonomic nervous system contributes to these adjustments by helping regulate blood-vessel tone and cardiovascular responses. However, these symptoms do not automatically mean that an autonomic disorder is present.

Dehydration, anemia, medication effects, insufficient sleep, abnormal heart rhythms, and other medical conditions may produce a similar pattern.

The timing, frequency, associated symptoms, and overall clinical context are therefore important.

Quick Answer

When you stand up, gravity causes some blood to shift toward the lower body.

The body responds by adjusting blood-vessel tone, heart rate, and other circulatory mechanisms to help maintain blood pressure and blood flow to the brain.

During this adjustment, some people may briefly experience:

• Lightheadedness
• A sensation of nearly losing balance
• Temporary visual dimming
• A faster heartbeat
• Palpitations

The autonomic nervous system is involved in this response, but it is not the only factor.

Heart function, blood volume, hydration, hormones, kidney function, medications, and general health also contribute.

What Happens in the Body When You Stand Up?

While lying down or sitting, blood is distributed differently than it is while standing.

After you stand, gravity can cause some blood to move toward the legs and lower abdomen.

The body must respond quickly to maintain adequate circulation.

This response may involve changes in:

• Heart rate
• Blood-vessel tone
• Blood pressure
• Cardiac output
• Blood flow to the brain

The autonomic nervous system helps coordinate some of these changes.

Blood vessels may narrow appropriately, and heart rate may increase to support circulation during the change in posture.

This process is not controlled by the autonomic nervous system alone. It also depends on:

• The heart
• The blood vessels
• Blood volume
• Hydration
• Hormonal regulation
• Kidney function
• Medications

A problem in any of these areas may affect how the body responds after standing.

Why Can Standing Cause Dizziness?

If the circulatory adjustment is not fast or effective enough, blood pressure or blood flow to the brain may temporarily decrease.

This may produce symptoms such as:

• Lightheadedness
• A "floating" or unsteady sensation
• Brief visual dimming
• Weakness
• A feeling that you may need to sit down again

This type of dizziness is not necessarily the same as rotational vertigo.

Some people describe it as feeling faint or unsteady rather than feeling that the room is spinning.

The exact sensation matters because different forms of dizziness may have different explanations.

Why Does the Heart Beat Faster?

A faster heartbeat can be part of the body's attempt to maintain circulation after standing.

When blood shifts toward the lower body, the body may respond by increasing heart rate and adjusting blood-vessel tone.

This does not necessarily mean that the heart itself is abnormal.

However, a rapid or irregular heartbeat may also occur for reasons unrelated to normal postural adjustment.

Possible contributing factors include:

• Dehydration
• Anemia
• Medication effects
• Sleep deprivation
• Physical exhaustion
• Anxiety or intense emotional stress
• Infection or another systemic condition
• Abnormal heart rhythms

For this reason, a faster heartbeat after standing should not automatically be described as "sympathetic overactivity" or a loss of autonomic balance.

Those phrases do not identify the underlying cause.

Is This Always an Autonomic Nervous System Problem?

No.

The autonomic nervous system participates in blood-pressure and heart-rate regulation, so autonomic dysfunction may be one possible explanation.

However, similar symptoms may occur with several other conditions.

Dehydration

A reduced circulating blood volume may make it harder for the body to maintain blood pressure after standing.

Recent illness, heat exposure, heavy sweating, reduced fluid intake, or other causes of fluid loss may contribute.

Anemia

When the blood's oxygen-carrying capacity is reduced, symptoms may include fatigue, palpitations, weakness, or dizziness.

The symptom pattern alone cannot confirm anemia.

Medication Effects

Some medications may affect:

• Blood pressure
• Heart rate
• Blood-vessel tone
• Fluid balance

The timing of symptoms in relation to a new medication or dose change may be clinically relevant.

Medication should not be stopped or adjusted without appropriate medical guidance.

Insufficient Sleep and Fatigue

Sleep deprivation and physical exhaustion may worsen how a person experiences dizziness, palpitations, or general instability.

Poor sleep does not prove an autonomic disorder, but it may contribute to the overall symptom pattern.

Abnormal Heart Rhythms

Palpitations or a rapid heartbeat may sometimes arise from an abnormal cardiac rhythm.

This possibility becomes more important when the heartbeat feels irregular, symptoms are prolonged, or fainting or chest discomfort occurs.

What Details Help Clarify the Cause?

The symptom pattern often provides more useful information than the symptom name alone.

Relevant questions include:

• Does it occur only after standing?
• Does it happen after getting out of bed, rising from a chair, or both?
• How long does the dizziness last?
• Does the heart feel fast, irregular, or both?
• Has actual fainting occurred?
• Is chest pain present?
• Is there shortness of breath?
• Has fluid intake recently been low?
• Has there been vomiting, diarrhea, fever, or heavy sweating?
• Did the symptoms begin after starting or changing a medication?
• Has there been significant sleep loss or exhaustion?
• Could blood loss or anemia be a possibility?
• Are there any new neurological symptoms?

A symptom diary may help identify patterns, but it cannot replace medical evaluation when symptoms are recurrent or concerning.

How May These Symptoms Be Evaluated?

Evaluation depends on the medical history, symptom pattern, and physical examination.

A clinician may consider:

• Heart rate while lying and standing
• Blood pressure while lying and standing
• An electrocardiogram
• Blood tests selected according to the history
• Review of medications
• Cardiac or other organ-specific evaluation
• Selected autonomic-function testing

Not every person needs every test.

Autonomic testing may help evaluate certain physiological responses, but one test cannot determine:

• The cause of every episode of dizziness
• The cause of every palpitation
• A person's overall sympathetic–parasympathetic "balance"
• Whether all cardiac, endocrine, hematological, or medication-related causes have been excluded
• Which treatment is appropriate for an individual

Test results must be interpreted together with symptoms, medical history, examination findings, and other appropriate investigations.

An abnormal result does not automatically establish one diagnosis.

A normal result also does not mean that the symptoms are not real.

When Should You Consider Medical Evaluation?

Medical evaluation should be considered when the symptoms:

• Occur repeatedly
• Are becoming more severe
• Last longer than before
• Interfere with daily activities
• Create a risk of falling
• Affect driving or exercise safety
• Begin after a new medication
• Occur with an irregular heartbeat
• Are associated with increasing weakness or fatigue

Recurrent symptoms deserve evaluation even when each episode resolves quickly.

The goal is not simply to label the symptoms as autonomic. It is to consider autonomic and non-autonomic explanations together.

When Is Urgent Evaluation Needed?

Do not assume that severe symptoms are caused by a benign postural response or an autonomic imbalance.

Seek urgent medical evaluation for:

• Fainting
• Chest pain
• Severe shortness of breath
• Fainting during exercise
• Delayed recovery after loss of consciousness
• Persistent severe or irregular palpitations
• Sudden weakness or numbness
• Sudden difficulty speaking
• Sudden difficulty walking
• Sudden vision changes
• A seizure
• A sudden severe unexplained headache

Call 911 in the United States—or your local emergency number—when symptoms suggest an immediate medical emergency.

Sudden neurological symptoms require urgent assessment even if they improve after a short time.

Key Takeaway

Feeling dizzy and noticing a faster heartbeat after standing may reflect the body's attempt to maintain blood pressure and blood flow during a change in posture.

The autonomic nervous system contributes by helping regulate blood vessels and heart-rate responses.

However, the same symptoms may also occur with:

• Dehydration
• Anemia
• Medication effects
• Poor sleep
• Abnormal heart rhythms
• Other medical conditions

Symptoms alone cannot confirm an autonomic disorder.

Recurrent symptoms, fainting, chest pain, severe shortness of breath, persistent palpitations, or new neurological symptoms require medical evaluation.

Frequently Asked Questions

Why does my heart race when I stand up?

Standing causes blood to shift toward the lower body. The body may increase heart rate and adjust blood-vessel tone to help maintain circulation.

A faster heartbeat may be part of this response, but dehydration, anemia, medications, anxiety, insufficient sleep, or an abnormal heart rhythm may also contribute.

Is dizziness when standing always caused by low blood pressure?

No.

A temporary blood-pressure change may contribute, but dizziness may have several possible causes. The symptom pattern, medications, hydration status, heart rhythm, and other medical factors should be considered.

Does this mean my autonomic nervous system is damaged?

Not necessarily.

The autonomic nervous system is involved in the response to standing, but symptoms alone cannot establish that it is damaged or functioning abnormally.

Can dehydration cause both dizziness and a fast heartbeat?

Dehydration may reduce circulating blood volume and contribute to dizziness and a faster heartbeat, particularly during changes in posture.

However, the symptoms alone cannot identify dehydration as the cause.

Can lack of sleep make these symptoms worse?

Insufficient sleep and fatigue may affect how a person experiences dizziness, palpitations, and physical instability.

Poor sleep may contribute to symptoms, but it does not confirm an autonomic disorder.

Should I stop a medication that may be causing the symptoms?

Do not stop or change prescribed medication without consulting the prescribing clinician.

A healthcare professional can review whether the medication, dose, timing, or another factor may be contributing.

When should I seek urgent care?

Urgent evaluation is needed when dizziness or a rapid heartbeat occurs with fainting, chest pain, severe shortness of breath, prolonged or irregular palpitations, or sudden neurological symptoms.