Types of dizziness — understanding what you feel
| Type | What it feels like | Common causes |
|---|---|---|
| Vertigo | Room spinning, or feeling you are moving when still | BPPV, labyrinthitis, Meniere disease, stroke |
| Presyncope / Lightheadedness | About to faint, grey-out | Low blood pressure, dehydration, anaemia, arrhythmia |
| Disequilibrium | Unsteadiness when walking, off-balance | Peripheral neuropathy, cerebellar disease, medications |
| Non-specific dizziness | Floating or detached feeling | Anxiety, hyperventilation, medication side effects |
Blood tests ordered for dizziness
| Test | What it checks for |
|---|---|
| CBC (haemoglobin) | Anaemia — low Hb reduces oxygen delivery to the brain |
| Glucose (fasting or random) | Hypoglycaemia causes sudden dizziness; hyperglycaemia also |
| Electrolytes (Na, K) | Low sodium (hyponatraemia) — a classic cause of dizziness |
| TSH | Hypothyroidism and hyperthyroidism both cause dizziness |
| Blood pressure (lying and standing) | Orthostatic hypotension — BP drops on standing → dizziness |
| Vitamin B12 | B12 deficiency causes neuropathy, poor balance and dizziness |
| ECG | Arrhythmia (atrial fibrillation) causing palpitations and dizziness |
| Iron studies / ferritin | Iron deficiency even without anaemia can cause lightheadedness |
The most common causes explained
BPPV (Benign Paroxysmal Positional Vertigo) — most common cause of vertigo
Tiny calcium crystals (otoliths) in the inner ear displace into the semicircular canals, causing intense brief spinning (5-30 seconds) when rolling over in bed, looking up, or bending forward. Blood tests are normal. Diagnosed with the Dix-Hallpike test. Treated with the Epley manoeuvre (repositioning the crystals) which works in over 80% of cases.
Vestibular neuritis / Labyrinthitis
Viral infection of the vestibular nerve or inner ear causing prolonged vertigo (days) with nausea, unable to stand. No hearing loss (neuritis) or with hearing loss (labyrinthitis). Blood tests usually normal. Treated with short-course steroids and vestibular suppressants.
Orthostatic hypotension — dizziness on standing
Blood pressure drops by ≥20 mmHg systolic (or ≥10 mmHg diastolic) within 3 minutes of standing, causing lightheadedness. Causes: dehydration, antihypertensive medications, diuretics, Parkinson disease, autonomic neuropathy (from diabetes). Measured with lying and standing blood pressure. Treated by increasing fluid and salt intake, adjusting medications, compression stockings.
Anaemia and iron deficiency
Moderate-to-severe anaemia reduces oxygen delivery to the brain, causing lightheadedness, especially on standing or exertion. Even iron deficiency without frank anaemia can cause dizziness. CBC and ferritin are the key tests.
Hypoglycaemia (low blood sugar)
Blood sugar below 70 mg/dL causes sweating, shakiness, dizziness and confusion. Particularly affects diabetic patients on insulin or sulfonylureas. Test with a random blood glucose during symptoms.
Questions to ask your doctor
- Is my dizziness vertigo (spinning) or lightheadedness (about to faint)?
- What is my blood pressure lying and standing?
- Should I have a Dix-Hallpike test?
- Do I need an MRI of the brain?
- Are any of my medications causing dizziness?