The challenge with dizziness is that it’s a symptom, not a diagnosis. Dizziness can result from problems in the inner ear, the cardiovascular system, the nervous system, or from metabolic and systemic conditions throughout the body. Some causes are benign; others require prompt attention. Many are highly treatable once identified.

Blood tests play an important role in evaluating dizziness because many common causes — anemia, blood sugar problems, thyroid dysfunction, electrolyte imbalances — are detectable through simple blood work. While not all causes of dizziness show up on blood tests (inner ear problems, for example, don’t), identifying or ruling out metabolic causes is often the logical first step in evaluation.

This article explores the different types of dizziness, what underlying conditions might be responsible, and what blood tests can reveal about why you’re feeling unsteady.

Understanding Dizziness

People use the word “dizziness” to describe many different sensations, and distinguishing between them is crucial for identifying the cause. The type of dizziness you experience provides important diagnostic clues that help determine whether the problem originates in the inner ear, cardiovascular system, brain, or metabolic processes throughout the body.

When describing dizziness to a healthcare provider, try to be as specific as possible. Is the room spinning, or do you feel like you might faint? Does it happen when you stand up or when you move your head? How long does it last — seconds, minutes, or hours? These details matter enormously for diagnosis.

Types of dizziness:

Vertigo: A false sensation of movement — feeling like you or your surroundings are spinning, tilting, rocking, or swaying when nothing is actually moving. True vertigo is usually caused by problems in the vestibular system — the inner ear structures and neural pathways that sense head position and motion. Less commonly, vertigo results from problems in the brain (brainstem or cerebellum). People with vertigo often feel nauseated, may vomit, and have trouble walking or standing because their brain is receiving conflicting information about body position. Common causes include benign paroxysmal positional vertigo (BPPV) — brief intense spinning triggered by head position changes, vestibular neuritis — inflammation of the balance nerve causing prolonged vertigo, Meniere’s disease — episodes of vertigo with hearing loss and tinnitus, and, rarely, stroke affecting the brainstem or cerebellum — a medical emergency.

Presyncope (near-fainting): Feeling like you might pass out — lightheadedness, wooziness, weakness, warmth, tunnel vision, dimming or graying of vision, or feeling like consciousness is slipping away. This type of dizziness typically results from insufficient blood flow or oxygen delivery to the brain. The brain is extremely sensitive to reductions in blood supply — even brief decreases cause symptoms. Common causes include orthostatic hypotension (blood pressure dropping when you stand up), dehydration (reduced blood volume), anemia (reduced oxygen-carrying capacity), heart rhythm problems (irregular, too fast, or too slow heartbeat compromising cardiac output), blood sugar drops (hypoglycemia depriving the brain of fuel), and vasovagal responses (the “fainting” response to triggers like heat, prolonged standing, pain, or emotional stress). This type of dizziness often improves when lying down and worsens when standing.

Disequilibrium: A sense of imbalance or unsteadiness, particularly when walking — feeling like you might fall, difficulty walking in a straight line, or needing to hold onto things for balance, but without spinning or the feeling of near-fainting. This type often relates to problems with the sensory systems that maintain balance (vision, inner ear vestibular function, and proprioception — the sense of body position from receptors in the feet and legs) or with the brain’s ability to integrate this information. Causes include peripheral neuropathy (nerve damage in the legs, common in diabetes and B12 deficiency, that impairs proprioception), inner ear dysfunction affecting both ears gradually, certain medications (especially sedatives and those affecting the nervous system), cerebellar problems, Parkinson’s disease and other neurological conditions, and age-related balance decline (multiple systems gradually become less efficient).

Nonspecific dizziness: Vague lightheadedness, floating sensation, feeling “spaced out,” or a “swimming” feeling in the head that doesn’t fit neatly into the above categories. This type of dizziness is common with anxiety and panic disorders, hyperventilation (which changes blood CO2 levels and brain blood flow), medication side effects, chronic fatigue and sleep deprivation, and various metabolic conditions causing general malaise. It’s often described as feeling disconnected from surroundings or like moving through a fog.

When dizziness suggests a metabolic or systemic cause:

Blood tests are most useful when dizziness has characteristics suggesting a metabolic or systemic problem rather than a primary inner ear or neurological cause. Consider metabolic causes when:

• Dizziness occurs primarily with standing up (orthostatic pattern — suggests low blood pressure, dehydration, anemia, or autonomic dysfunction)
• Dizziness is accompanied by fatigue, weakness, or pallor (classic signs of anemia)
• Dizziness relates to meals or eating patterns — before meals, after meals, or when meals are skipped (suggests blood sugar issues)
• Dizziness comes with other systemic symptoms (unexplained weight changes, temperature intolerance, palpitations suggest thyroid dysfunction)
• Dizziness accompanies numbness, tingling, or balance problems in the legs (suggests B12 deficiency or neuropathy)
• Dizziness is constant or persistent rather than episodic spinning (chronic dizziness is less likely to be inner ear)
• Dizziness occurs without true vertigo — no sensation of the room spinning
• Dizziness doesn’t fit typical patterns for inner ear conditions (BPPV, for example, causes brief episodes triggered specifically by head position changes)
• Dizziness is new and accompanied by symptoms of chronic disease

Warning signs requiring immediate medical attention:

Seek emergency care immediately for dizziness accompanied by any of these symptoms, which could indicate stroke, heart attack, or other serious conditions:

• Sudden severe headache — often described as “the worst headache of my life”
• Weakness, numbness, or paralysis on one side of the body
• Facial drooping or difficulty speaking, slurred speech
• Vision changes — double vision, sudden vision loss, visual field cuts
• Difficulty walking, severe imbalance, inability to stand, or falling
• Chest pain, pressure, or tightness
• Rapid, irregular, or very slow heartbeat
• Loss of consciousness, confusion, or altered mental status
• Severe vomiting or inability to keep fluids down
• High fever with stiff neck (possible meningitis)
• Recent head trauma followed by worsening symptoms
• Dizziness that is completely new and severe in onset

The “FAST” signs of stroke — Face drooping, Arm weakness, Speech difficulty, Time to call emergency services — are particularly important. Stroke affecting the brainstem or cerebellum can present primarily as severe vertigo, and distinguishing this from benign inner ear vertigo can be challenging without specialized examination.

Anemia: A Leading Cause of Dizziness

Anemia — a deficiency of red blood cells or hemoglobin — is one of the most common and most treatable causes of dizziness and lightheadedness. Affecting an estimated 1.6 billion people worldwide, anemia is something every healthcare provider should consider when evaluating dizziness. The connection between anemia and dizziness is direct and logical: the brain requires constant oxygen delivery, consuming about 20% of the body’s oxygen supply despite comprising only 2% of body weight. Anemia reduces the blood’s oxygen-carrying capacity, and the brain is one of the first organs to show symptoms.

The good news is that anemia is easily identified through blood testing and, once the type is determined, usually highly treatable. Treating anemia often dramatically improves or completely eliminates dizziness.

How anemia causes dizziness:

• Reduced oxygen delivery: Hemoglobin in red blood cells carries oxygen from the lungs to tissues throughout the body. With less hemoglobin available, less oxygen reaches the brain with each heartbeat. The brain is exquisitely sensitive to oxygen levels — even mild reductions trigger symptoms including lightheadedness, difficulty concentrating, and feeling faint. This is the most direct mechanism linking anemia to dizziness.
• Cardiovascular compensation: The body attempts to maintain adequate oxygen delivery despite reduced hemoglobin by increasing heart rate and cardiac output. The heart beats faster and pumps harder. While this compensation helps maintain oxygen delivery, the tachycardia (rapid heart rate) itself can cause palpitations, a sense of unsteadiness, and awareness of heartbeat that feels like dizziness.
• Orthostatic intolerance: When you stand up, gravity pulls blood toward your legs. Normally, blood vessels quickly constrict and heart rate increases to maintain blood pressure and brain perfusion. Anemia impairs this compensatory response — with less oxygen-carrying capacity and often less blood volume, the body struggles to maintain adequate brain blood flow when upright. This causes lightheadedness when standing, sometimes progressing to near-fainting or actual fainting.
• Exertional symptoms: During physical activity, muscles demand more oxygen. In anemia, the body can’t meet this increased demand. Blood is shunted toward working muscles and away from other areas. The brain receives even less oxygen during exertion, causing dizziness, shortness of breath, fatigue, and sometimes chest discomfort.
• Reduced blood viscosity: Severe anemia makes blood “thinner” and less viscous. While this makes blood flow more easily, it also affects blood pressure regulation and may contribute to symptoms.

Characteristics of anemia-related dizziness:

• Typically lightheadedness or near-fainting rather than true spinning vertigo — the room doesn’t spin, but you feel unsteady or like you might pass out
• Worse when standing up quickly (orthostatic) — classic pattern of dizziness on rising from lying or sitting
• Worse with physical exertion — walking up stairs, exercise, even prolonged walking may trigger symptoms
• Often accompanied by other anemia symptoms: fatigue (often profound), weakness, shortness of breath, pallor (pale skin, pale nail beds, pale inner eyelids), and cold intolerance
• May be associated with rapid heartbeat, pounding heart, or awareness of heartbeat
• Typically gradual onset as anemia develops over time — people often adapt to surprisingly low hemoglobin levels before symptoms become severe
• Improves when lying down (gravity helps blood flow to the brain)

Types of anemia causing dizziness:

Iron deficiency anemia: The most common type of anemia worldwide, affecting hundreds of millions of people. Iron is essential for hemoglobin production. Iron deficiency develops from inadequate dietary intake, poor absorption (celiac disease, gastric bypass, H. pylori infection), blood loss (menstruation, GI bleeding from ulcers or cancer, frequent blood donation), or increased demands (pregnancy, rapid growth). Iron deficiency often develops slowly, so people may adapt to progressively lower hemoglobin levels. They may not recognize how unwell they’ve become until treated and feel dramatically better.

Vitamin B12 deficiency: Causes macrocytic anemia (larger than normal red blood cells) plus neurological symptoms. B12 deficiency is particularly important because it affects both oxygen delivery (through anemia) and nervous system function (affecting balance, sensation, and cognition). Dizziness may result from the anemia, from neurological effects, or both. Common in vegetarians and vegans (B12 is found almost exclusively in animal products), older adults (stomach acid decreases with age, impairing B12 absorption), people taking metformin or proton pump inhibitors long-term, and those with pernicious anemia (autoimmune destruction of the cells that produce intrinsic factor needed for B12 absorption) or GI conditions affecting absorption.

Folate deficiency: Also causes macrocytic anemia. Often occurs with poor diet, alcoholism (alcohol impairs folate absorption and increases requirements), malabsorption, or increased demands during pregnancy. Folate deficiency can develop relatively quickly — body stores are limited.

Anemia of chronic disease: Occurs with chronic inflammation, infection, cancer, or autoimmune conditions. The body sequesters iron as a defense mechanism, limiting its availability for red blood cell production. This type of anemia often accompanies the underlying condition’s other symptoms.

Other causes: Hemolytic anemias (red blood cells destroyed prematurely), bone marrow disorders, chronic kidney disease (reduced erythropoietin production), and inherited anemias like thalassemia.

What to test:

Complete Blood Count (CBC) — identifies anemia through hemoglobin and hematocrit levels. Also provides MCV (mean corpuscular volume) which helps classify the type: low MCV (microcytic) suggests iron deficiency; high MCV (macrocytic) suggests B12 or folate deficiency; normal MCV (normocytic) occurs with anemia of chronic disease and some other causes.

Ferritin — reveals iron stores. Ferritin can be low even when hemoglobin is still in the “normal” range, and low ferritin itself can cause symptoms including dizziness and fatigue. Ferritin is often the earliest marker of developing iron deficiency.

Serum iron, TIBC, transferrin saturation — further characterize iron status and help distinguish iron deficiency from other causes of anemia.

Vitamin B12 — essential to test, especially if MCV is elevated or neurological symptoms (numbness, tingling, balance problems) are present. B12 deficiency is common and treatable but can cause permanent neurological damage if not identified.

Folate — often tested alongside B12, as both cause macrocytic anemia and can occur together.

Reticulocyte count — shows whether the bone marrow is producing new red blood cells appropriately. Helps distinguish between decreased production and increased destruction of red blood cells.

Blood Sugar Abnormalities

Blood sugar problems — both low blood sugar (hypoglycemia) and the fluctuations associated with diabetes and insulin resistance — are common causes of dizziness. The brain depends almost exclusively on glucose for fuel, making it highly sensitive to blood sugar changes. Unlike muscles, which can switch to burning fat when glucose is limited, neurons require a constant glucose supply to function. This makes dizziness one of the earliest symptoms of blood sugar problems.

Blood sugar-related dizziness is often overlooked because people don’t connect their symptoms to eating patterns. Understanding this connection can lead to simple, effective solutions.

Hypoglycemia (low blood sugar):

When blood sugar drops below normal levels, the brain is one of the first organs to show symptoms. The body has multiple defense mechanisms to prevent dangerous hypoglycemia, and the activation of these defenses produces many of the symptoms people experience. Hypoglycemic dizziness results from:

• Brain glucose deprivation: Neurons require constant glucose to generate energy and maintain their electrical activity. Even brief reductions impair brain function, causing lightheadedness, difficulty concentrating, confusion, and feeling faint. Severe hypoglycemia can cause seizures or loss of consciousness.
• Adrenaline (epinephrine) release: When blood sugar starts dropping, the body releases adrenaline as an emergency response to raise glucose levels. Adrenaline causes rapid heartbeat, sweating, trembling, pallor, and anxiety — symptoms that often feel like dizziness or the feeling that something is very wrong. This adrenaline surge is why people feel “shaky” with low blood sugar.
• Other counter-regulatory hormones: Glucagon, cortisol, and growth hormone are also released to raise blood sugar. These contribute to the overall sense of being unwell.
• Autonomic nervous system activation: The autonomic symptoms of hypoglycemia — sweating, pallor, rapid heart rate, tremor — combine to create a lightheaded, unsteady feeling.

Hypoglycemic dizziness typically has recognizable patterns:

• Occurs when meals are skipped or delayed — the classic scenario is dizziness in late afternoon if lunch was light or skipped
• Happens several hours after eating (reactive hypoglycemia) — particularly after high-carbohydrate meals that cause an insulin overshoot
• Is accompanied by specific symptoms: shakiness, sweating, hunger, irritability, difficulty thinking, anxiety, and rapid heartbeat
• Improves rapidly (within 10-15 minutes) after eating or drinking something containing sugar — this rapid response to food is a key diagnostic clue
• May occur in the morning before breakfast, especially if dinner the night before was early or light
• Can wake you from sleep at night, sometimes with sweating and nightmares
• Often produces intense hunger along with dizziness

Reactive hypoglycemia and insulin resistance:

Some people experience a paradoxical pattern — dizziness 2-4 hours after eating rather than from skipping meals. This reactive hypoglycemia occurs when:

• Blood sugar spikes after eating carbohydrates (particularly refined carbs and sugars)
• The pancreas releases insulin to bring blood sugar down
• Insulin is released in excess — overshooting the amount needed
• Blood sugar then crashes below normal
• The low blood sugar triggers dizziness, shakiness, and other symptoms

This pattern is particularly common in people with insulin resistance — a condition where cells don’t respond efficiently to insulin, prompting the pancreas to produce more. The blood sugar “rollercoaster” — spiking high after meals then crashing low — causes symptoms even when average glucose levels appear acceptable. Insulin resistance is extremely common, affecting a large percentage of adults, and often precedes type 2 diabetes by years or decades.

Diabetes and hyperglycemia:

Diabetes can cause dizziness through multiple mechanisms that differ from simple hypoglycemia:

• Dehydration: Chronically elevated blood sugar causes increased urination (osmotic diuresis) as the kidneys try to eliminate excess glucose. This leads to dehydration and reduced blood volume, causing lightheadedness especially when standing.
• Electrolyte imbalances: The fluid and electrolyte shifts associated with high blood sugar affect nerve and muscle function. Sodium, potassium, and other electrolytes can become imbalanced.
• Diabetic autonomic neuropathy: Over time, high blood sugar damages the autonomic nerves that control blood pressure regulation. This leads to orthostatic hypotension — the inability to maintain blood pressure when standing — and significant dizziness on position changes. This is one of the most common causes of dizziness in people with long-standing diabetes.
• Hypoglycemia from diabetes medications: Insulin and certain diabetes medications (particularly sulfonylureas) can cause blood sugar to drop too low, causing hypoglycemic dizziness as described above.
• Diabetic ketoacidosis (DKA): A serious complication of diabetes (usually type 1) causing high blood sugar, ketone production, and acidosis. Symptoms include dizziness, nausea, vomiting, abdominal pain, rapid breathing, and altered mental status. This is a medical emergency.

What to test:

Fasting glucose — measures blood sugar after an overnight fast. Results are interpreted in categories: normal, prediabetes, and diabetes.

HbA1c — reflects average blood sugar over 2-3 months, providing a longer-term picture than a single glucose measurement. Like fasting glucose, results are categorized as normal, prediabetes, or diabetes.

Fasting insulin — identifies insulin resistance even when glucose is still normal. Elevated fasting insulin suggests the body is working hard to keep blood sugar controlled — the pancreas is producing extra insulin to compensate for resistant cells. This metabolic state is associated with blood sugar instability and dizziness.

Thyroid Dysfunction

Both hypothyroidism and hyperthyroidism can cause dizziness, though through different mechanisms. Thyroid disorders are common — affecting up to 10% of adults — and are easily identified through blood testing.

Hypothyroidism and dizziness:

An underactive thyroid can cause dizziness through several pathways:

• Cardiovascular effects: Hypothyroidism slows heart rate and can reduce cardiac output, potentially leading to reduced blood flow to the brain
• Anemia: Hypothyroidism is associated with anemia, which itself causes dizziness
• Fluid and electrolyte changes: Thyroid hormones affect fluid balance and electrolytes
• Autonomic dysfunction: Hypothyroidism can affect autonomic nervous system function, contributing to orthostatic intolerance
• Inner ear effects: Some research suggests thyroid hormone affects inner ear function
• General metabolic slowing: The overall metabolic slowdown affects all body systems including those involved in balance

Hypothyroid dizziness is often described as lightheadedness, unsteadiness, or “foggy” feeling rather than true vertigo. It typically develops gradually and is accompanied by other hypothyroid symptoms: fatigue, weight gain, cold intolerance, constipation, dry skin, and brain fog.

Hyperthyroidism and dizziness:

An overactive thyroid causes dizziness through different mechanisms:

• Cardiovascular effects: Rapid heart rate, palpitations, and increased cardiac output can cause a sense of unsteadiness
• Atrial fibrillation: Hyperthyroidism significantly increases risk of atrial fibrillation, an irregular heart rhythm that can cause dizziness, near-fainting, or stroke
• Anxiety and hyperventilation: The anxiety and restlessness of hyperthyroidism can lead to hyperventilation, which causes dizziness
• Heat intolerance: Overheating and sweating can contribute to dehydration and dizziness
• Metabolic overdrive: The accelerated metabolism affects all systems, creating a sense of unsteadiness

Hyperthyroid dizziness often accompanies palpitations, tremor, anxiety, weight loss despite good appetite, and heat intolerance.

What to test:

TSH — the primary screening test. Elevated TSH suggests hypothyroidism; suppressed TSH suggests hyperthyroidism.

Free T4 and Free T3 — measure actual thyroid hormone levels when TSH is abnormal.

TPO antibodies — identify autoimmune thyroid disease (Hashimoto’s or Graves’).

Electrolyte Imbalances

Electrolytes — sodium, potassium, calcium, magnesium — are essential for nerve and muscle function, including the systems that maintain blood pressure and balance. Imbalances in any of these can cause dizziness.

Sodium (hyponatremia and hypernatremia):

Sodium is critical for fluid balance and nerve function. Low sodium (hyponatremia) is a common cause of dizziness, particularly in older adults, people taking certain medications (diuretics, antidepressants), and with conditions causing fluid retention. Symptoms range from mild lightheadedness to confusion and seizures in severe cases. High sodium (hypernatremia) usually indicates dehydration and also causes dizziness and altered mental status.

Potassium:

Potassium is essential for heart function. Both low potassium (hypokalemia) and high potassium (hyperkalemia) can cause cardiac arrhythmias leading to dizziness, palpitations, or near-fainting. Low potassium also causes muscle weakness that may contribute to unsteadiness.

Calcium:

Calcium affects nerve and muscle function. High calcium (hypercalcemia) causes fatigue, weakness, and dizziness — often described as “feeling like you’re moving through fog.” Low calcium (hypocalcemia) causes muscle cramps, tingling, and can affect heart rhythm.

Magnesium:

Magnesium deficiency is common and often overlooked. Low magnesium can cause dizziness, weakness, tremor, and cardiac arrhythmias. It also makes potassium deficiency harder to correct.

What to test:

Sodium, Potassium, Calcium, Magnesium — a comprehensive metabolic panel covers most of these.

Creatinine and eGFR — kidney function affects electrolyte balance.

Dehydration and Blood Pressure

Dehydration is one of the simplest causes of dizziness — and one of the most easily corrected. When you’re dehydrated, blood volume decreases, blood pressure drops, and blood flow to the brain is compromised. Despite being simple in concept, dehydration is extremely common and frequently overlooked as a cause of lightheadedness.

Many people chronically under-hydrate without realizing it. They’ve adapted to the mild dehydration and don’t recognize their symptoms as fluid-related. When asked, they often report drinking far less water than recommended and relying on caffeinated or alcoholic beverages that can actually worsen dehydration.

How dehydration causes dizziness:

• Reduced blood volume: Water makes up a significant portion of blood plasma. When you’re dehydrated, blood volume decreases. Less blood means lower blood pressure and reduced blood flow to the brain. The brain is highly sensitive to even small reductions in blood supply.
• Orthostatic hypotension: Dehydration significantly worsens the normal blood pressure drop that occurs when standing up. With reduced blood volume, the cardiovascular system struggles to compensate for gravity’s effect of pulling blood toward the legs. Blood pressure falls, brain perfusion drops, and dizziness results. This is why dehydration-related dizziness is often worst when standing.
• Electrolyte imbalances: Fluid loss often involves electrolyte loss as well, particularly sodium lost in sweat. Electrolyte imbalances affect nerve and muscle function, contributing to dizziness and weakness.
• Thickened blood: Dehydration makes blood more concentrated and viscous. While blood flow continues, this change in blood properties may affect circulation and oxygen delivery.
• Increased heart rate: The heart beats faster to compensate for reduced blood volume, which some people perceive as palpitations or unsteadiness.

Dehydration-related dizziness has recognizable characteristics:

• Worse when standing up — the classic orthostatic pattern
• Improves when lying down — gravity helps blood return to the brain
• Accompanied by thirst, dry mouth, and decreased urination
• Urine is dark yellow rather than pale — a reliable indicator of hydration status
• Associated with fatigue, headache, and decreased concentration
• More common in hot weather, after exercise, or during illness with fever, vomiting, or diarrhea
• Responds quickly to fluid replacement — improvement often noticeable within an hour

Risk factors for dehydration:

• Hot weather and heat exposure
• Exercise, especially prolonged or in heat
• Fever, vomiting, or diarrhea
• Diuretic medications (“water pills”)
• Diabetes with high blood sugar (causes increased urination)
• Older age — thirst sensation decreases with age
• Alcohol consumption — alcohol is a diuretic
• High caffeine intake — caffeine has mild diuretic effects
• Simply not drinking enough throughout the day

Orthostatic hypotension:

Orthostatic (postural) hypotension is a significant drop in blood pressure within a few minutes of standing. It’s a very common cause of dizziness, especially in older adults. When you stand, blood pools in the legs due to gravity. Normally, baroreceptors (pressure sensors) detect the reduced blood return to the heart and trigger rapid compensatory responses: heart rate increases and blood vessels constrict to maintain blood pressure and brain perfusion. When these reflexes are impaired or overwhelmed, blood pressure falls and dizziness results.

Symptoms of orthostatic hypotension include:

• Lightheadedness or dizziness upon standing
• Dimming or graying of vision
• Weakness
• Feeling faint or actually fainting (syncope)
• Symptoms usually peak within seconds of standing and improve within a few minutes if you remain upright, or immediately if you sit or lie down

Causes of orthostatic hypotension include:

• Dehydration — the most common and most easily corrected cause
• Medications — blood pressure medications (especially when newly started or increased), diuretics, antidepressants, alpha-blockers for prostate problems, and many others
• Autonomic nervous system disorders — including diabetic autonomic neuropathy, Parkinson’s disease, multiple system atrophy, and pure autonomic failure
• Prolonged bed rest or immobilization — blood vessels lose their ability to constrict effectively
• Anemia — reduced blood volume and oxygen-carrying capacity
• Blood loss — obvious or occult
• Aging — baroreceptor reflexes naturally slow with age
• Adrenal insufficiency — reduced cortisol and aldosterone affect blood pressure regulation

Orthostatic hypotension is diagnosed by measuring blood pressure in lying and standing positions. If you experience dizziness primarily when standing, mention this pattern to your healthcare provider.

Vitamin Deficiencies

Several vitamin deficiencies can cause dizziness, often through effects on the nervous system or blood cell production.

Vitamin B12 deficiency:

B12 deficiency is particularly important because it causes both anemia (leading to dizziness from reduced oxygen delivery) and neurological problems (affecting balance and causing dizziness directly). Neurological symptoms can occur even without anemia.

B12-related dizziness may involve:

• Lightheadedness from anemia
• Unsteadiness and balance problems from peripheral neuropathy (damage to nerves in the legs affects proprioception)
• Vertigo-like symptoms from effects on the vestibular system
• Associated symptoms: tingling and numbness in hands and feet, weakness, memory problems

B12 deficiency is common in vegetarians/vegans (B12 is found almost exclusively in animal products), older adults (decreased absorption), people taking metformin or proton pump inhibitors, and those with pernicious anemia or GI conditions.

Vitamin D deficiency:

Vitamin D receptors exist in the inner ear and brain regions involved in balance. Some studies suggest that vitamin D deficiency is associated with BPPV (benign paroxysmal positional vertigo) and that correction of deficiency may reduce vertigo recurrence. Vitamin D also affects muscle function, and deficiency causes weakness that may contribute to unsteadiness.

What to test:

Vitamin B12 — essential, especially if neurological symptoms are present.

Vitamin D (25-OH) — given widespread deficiency, worth testing.

Folate — often tested alongside B12.

Homocysteine — elevated levels can indicate B12, folate, or B6 deficiency even when direct levels appear borderline.

Other Conditions Causing Dizziness

Cardiovascular causes:

Heart rhythm problems (arrhythmias) are an important cause of dizziness that should not be overlooked. The heart’s job is to pump blood to the brain and body; when its rhythm is abnormal, blood delivery can be compromised.

Tachyarrhythmias (too-fast rhythms): Rapid or irregular heartbeats may not allow adequate filling time between beats, reducing cardiac output. Atrial fibrillation is particularly common, affecting millions of adults. It becomes more common with age and is strongly associated with thyroid disorders. Symptoms include palpitations (awareness of irregular or rapid heartbeat), lightheadedness, fatigue, and shortness of breath. Atrial fibrillation also significantly increases stroke risk, so diagnosis is important.

Bradyarrhythmias (too-slow rhythms): Heart block, sick sinus syndrome, and medication effects can cause the heart to beat too slowly to maintain adequate blood pressure and brain perfusion. This can cause near-fainting or actual fainting, particularly with exertion or position changes.

Structural heart problems: Conditions affecting the heart valves (particularly aortic stenosis) or heart muscle can cause dizziness, particularly with exertion.

These cardiac causes require ECG or cardiac monitoring (Holter monitor, event monitor) to diagnose — blood tests can identify predisposing conditions (thyroid dysfunction, electrolyte imbalances) but don’t diagnose rhythm problems directly.

Medications:

Many medications cause dizziness as a side effect — it’s one of the most common medication-related complaints. If dizziness started after beginning a new medication or increasing a dose, medication effect should be high on the list of considerations. Common culprits include:

• Blood pressure medications — especially when first starting or increasing doses, these can cause orthostatic hypotension. Alpha-blockers (for prostate or blood pressure), beta-blockers, and diuretics are particularly common causes.
• Sedatives, sleep medications, and anti-anxiety medications — benzodiazepines, sleep aids, and antihistamines cause drowsiness and impaired balance
• Antidepressants — particularly when starting, stopping, or changing doses
• Pain medications — especially opioids, which cause sedation and can affect blood pressure
• Muscle relaxants — commonly cause dizziness and drowsiness
• Anti-seizure medications — many cause dizziness, particularly at higher doses
• Certain antibiotics — aminoglycosides can be toxic to the inner ear

If you suspect a medication is causing dizziness, discuss this with your prescriber. Often doses can be adjusted or alternative medications tried.

Inner ear disorders:

Inner ear (vestibular) problems are a leading cause of true vertigo — the sensation that you or the room is spinning. These conditions are diagnosed clinically and with specialized vestibular testing. Blood tests are normal but may be done to rule out other contributing factors. Common inner ear causes include BPPV (brief vertigo episodes triggered by head position changes), vestibular neuritis (prolonged vertigo from nerve inflammation), and Meniere’s disease (episodes of vertigo with hearing loss and tinnitus).

Anxiety and hyperventilation:

Anxiety is a very common cause of dizziness, and it’s important not to dismiss it as “just anxiety” — the dizziness is real even when the cause is psychological. Anxiety-related dizziness occurs through hyperventilation (rapid shallow breathing that changes blood CO2 levels and affects brain blood flow), chronic muscle tension affecting the neck and shoulders, heightened awareness and focus on body sensations, and the direct effects of stress hormones on the nervous system. Panic attacks characteristically include dizziness, palpitations, shortness of breath, and fear. Anxiety-related dizziness is often described as a floating, swimming, or unreal sensation. Blood tests are normal but help rule out medical causes, which can coexist with anxiety.

The Testing Strategy for Dizziness

Not everyone with dizziness needs extensive blood testing, but testing is valuable when dizziness is recurrent, unexplained, accompanied by other symptoms, or doesn’t fit patterns typical of inner ear conditions.

Core tests for unexplained dizziness:

Complete blood count:

• CBC — screens for anemia, a common cause

Iron studies:

• Ferritin — reveals iron deficiency even without anemia

Blood sugar:

• Fasting glucose
• HbA1c

Thyroid function:

• TSH
• Free T4 if TSH abnormal

Metabolic panel:

• Electrolytes (sodium, potassium)
• Calcium
• Kidney function (creatinine, eGFR)

Vitamins:

• Vitamin B12
• Vitamin D

Additional tests based on clinical picture:

• Magnesium if electrolyte imbalance suspected
• Fasting insulin if blood sugar symptoms present
• TPO antibodies if thyroid dysfunction found
• Cardiac enzymes if heart disease suspected

What to Do With the Results

If anemia is found:

Treatment depends on the type. Iron deficiency requires iron supplementation (and investigation of the cause if not obvious). B12 deficiency requires B12 supplementation — oral if mild, injections if severe or due to absorption problems. Treating anemia typically resolves dizziness over weeks as hemoglobin rises.

If blood sugar abnormalities are found:

Stabilizing blood sugar through diet, lifestyle, and sometimes medication reduces dizziness. Regular meals with protein and complex carbohydrates, avoiding sugar spikes, and treating insulin resistance all help. If diabetes is diagnosed, appropriate management is essential.

If thyroid dysfunction is found:

Hypothyroidism is treated with thyroid hormone replacement; hyperthyroidism may be treated with medication, radioactive iodine, or surgery depending on the cause. Dizziness typically improves as thyroid levels normalize over weeks to months.

If electrolyte imbalances are found:

Treatment involves correcting the imbalance and identifying the cause. Mild imbalances may respond to dietary changes; severe imbalances may require medical treatment. The underlying cause (medication effect, kidney problems, hormone issues) needs to be addressed.

When Tests Are Normal

Normal blood tests rule out anemia, thyroid dysfunction, blood sugar problems, electrolyte imbalances, and vitamin deficiencies. This is valuable information. If blood tests are normal, consider:

• Inner ear disorders: BPPV, vestibular neuritis, and Meniere’s disease are diagnosed clinically and with vestibular testing, not blood tests. A referral to an ENT or vestibular specialist may be helpful.
• Orthostatic hypotension: Diagnosed by measuring blood pressure lying and standing. May occur even with normal blood tests.
• Cardiac causes: Arrhythmias require ECG or cardiac monitoring to diagnose. Blood tests identify predisposing conditions but don’t diagnose rhythm problems directly.
• Medication effects: Review all medications with your healthcare provider.
• Anxiety and hyperventilation: These are diagnoses of exclusion after medical causes are ruled out. Treatment with stress management, breathing techniques, or therapy can help.
• Dehydration: Doesn’t always show on blood tests (unless severe). Improving hydration may help even if tests are normal.
• Migraine-associated vertigo: Migraines can cause dizziness even without headache.

Lifestyle Approaches for Managing Dizziness

Regardless of the cause, these strategies can help reduce dizziness:

• Stay hydrated: Dehydration is a common and easily corrected cause. Drink adequate water throughout the day.
• Rise slowly: If you experience orthostatic dizziness, move from lying to sitting to standing gradually. Sit on the edge of the bed for a moment before standing.
• Eat regularly: Don’t skip meals. Regular eating prevents blood sugar drops.
• Limit alcohol: Alcohol affects blood sugar, hydration, and directly impairs balance.
• Review medications: Ask your healthcare provider if any medications could be contributing.
• Manage stress: Anxiety and hyperventilation are common dizziness causes. Relaxation techniques help.
• Exercise regularly: Improves cardiovascular fitness and blood pressure regulation. Start slowly if currently dizzy.
• Get adequate sleep: Fatigue worsens dizziness.
• Avoid sudden head movements: If you have positional vertigo, moving slowly helps.

The Bottom Line

Dizziness is one of the most common symptoms people experience, and it has many possible causes — from benign and easily treated to serious conditions requiring immediate attention. The key to effective treatment is accurate diagnosis, which requires understanding what type of dizziness you’re experiencing and systematically evaluating possible causes.

Blood tests play an important role in dizziness evaluation because many common causes (anemia, blood sugar problems, thyroid dysfunction, electrolyte imbalances, vitamin deficiencies) are readily detectable through simple blood work. While not all causes of dizziness show up on blood tests — inner ear conditions and some cardiovascular problems require different types of evaluation — blood testing is often the logical first step.

The type of dizziness matters for guiding evaluation:

• Lightheadedness and near-fainting are more likely to have metabolic causes identifiable on blood tests — anemia, blood sugar problems, dehydration, electrolyte imbalances
• True vertigo (room spinning) is more likely related to the inner ear and requires vestibular evaluation
• Unsteadiness may indicate neurological causes including B12 deficiency or peripheral neuropathy

But there’s overlap, and comprehensive evaluation often includes both blood testing and other assessments depending on the clinical picture.

Don’t accept chronic dizziness as something you just have to live with. Many causes are highly treatable — anemia responds to iron or B12, blood sugar problems respond to dietary changes and medication, thyroid dysfunction responds to hormone treatment, and dehydration responds to increased fluid intake. Even when blood tests are normal, that information narrows the possibilities and guides further evaluation toward inner ear, cardiovascular, or other causes.

If you experience dizziness, pay attention to the pattern: When does it occur? What makes it better or worse? What other symptoms accompany it? These details help your healthcare provider determine the most likely cause and the most appropriate testing strategy.

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Key Takeaways

• Dizziness is a symptom with many possible causes — understanding the type of dizziness helps identify the source
• Anemia is a leading cause of lightheadedness — easily identified with CBC and iron studies, and highly treatable
• Blood sugar problems cause dizziness — both hypoglycemia and blood sugar instability from insulin resistance
• Thyroid dysfunction affects balance — both hypothyroidism and hyperthyroidism can cause dizziness
• Electrolyte imbalances impair nerve and muscle function — sodium, potassium, calcium, and magnesium all matter
• Vitamin B12 deficiency causes neurological symptoms — including dizziness and balance problems, sometimes before anemia develops
• Dehydration is simple but common — and easily corrected
• Warning signs require immediate attention — sudden severe headache, weakness, vision changes, or confusion need emergency evaluation
• Normal blood tests are still valuable — they rule out metabolic causes and guide further evaluation
• Inner ear conditions don’t show on blood tests — but blood tests help rule out other causes