Vertigo starts when your brain receives conflicting signals about where your body is in space. In most cases, the problem originates in the inner ear, where tiny structures responsible for detecting motion malfunction or send false signals. Roughly 14% of adults have experienced true spinning vertigo, and the peak age for a first episode falls between 50 and 60, with a second peak between 70 and 80. Women account for about 60% of cases.
Your Balance System, Briefly
Deep inside each ear sit three fluid-filled loops called semicircular canals. Each loop contains a sensory structure made of hair cells embedded in a gel-like cap called the cupula. When you turn your head, fluid inside the canal shifts, pushing the cupula and bending those hair cells. The hair cells convert that movement into nerve signals your brain reads as “head is turning left” or “head is tilting back.” When this system malfunctions on one side, your brain interprets the mismatch as spinning, even though you’re perfectly still.
Loose Crystals in the Inner Ear (BPPV)
The single most common cause of vertigo is benign paroxysmal positional vertigo, or BPPV. It starts when tiny calcium carbonate crystals that normally sit anchored on a membrane in the inner ear break loose and drift into one of the semicircular canals. Once there, they slosh around with every head movement, pushing fluid against those hair cells and generating false rotation signals.
The crystals typically detach because of age-related degeneration of the membrane they’re attached to, though a head injury, ear surgery, or prolonged bed rest can also shake them free. Any disorder of the inner ear that weakens the attachment point can set the process in motion. BPPV becomes more common with increasing age.
The hallmark of BPPV is that specific head positions trigger it. Tipping your head up or down, lying flat, rolling over in bed, or sitting up quickly can all set off a spell. Which movement does it varies from person to person, but a change in head position is almost always the trigger. The spinning sensation typically hits after a 2 to 5 second delay, lasts under a minute, and fades on its own. If you repeat the same movement several times, the response tends to weaken.
Fluid Buildup in the Inner Ear (Meniere’s Disease)
Meniere’s disease produces vertigo through a different mechanism: the fluid inside the inner ear’s sealed compartment gradually increases in volume, stretching and distorting the delicate membranes that separate it from surrounding fluid. This condition, called endolymphatic hydrops, doesn’t involve high pressure the way glaucoma pressurizes the eye. The membranes are extremely flexible, so the volume can increase with almost no measurable pressure change, less than 0.5 millimeters of mercury. Instead, the damage comes from the stretching itself, and possibly from small ruptures in those boundary membranes during an attack.
When a membrane ruptures, the chemically distinct fluids on either side mix, temporarily poisoning the hair cells and triggering a sudden, intense vertigo episode that can last several hours. These episodes often come with fluctuating hearing loss, ringing in the ear, and a feeling of fullness on the affected side. Meniere’s disease is most frequently diagnosed in the middle-age group, between roughly 41 and 65.
Nerve Inflammation After a Virus
Vestibular neuritis starts when a virus inflames the nerve that carries balance signals from your inner ear to your brain. Upper respiratory infections are involved in 43% to 46% of cases, and the viruses most commonly implicated include influenza, herpes simplex type 1, and several others that cause colds and flu-like illness. Herpes simplex type 1 is the most frequent culprit. Autopsy studies have found its genetic material in about two out of three vestibular nerve bundles, suggesting the virus can lie dormant in the nerve and reactivate later.
Unlike BPPV, vestibular neuritis doesn’t come and go with head position. It hits suddenly, often after a cold or respiratory illness, and causes severe, constant spinning that can last days. Nausea and vomiting are common. Because the inflammation damages the nerve on one side, the brain receives strong balance signals from one ear and weak or absent signals from the other, creating a dramatic mismatch it interprets as violent rotation. This form of vertigo also peaks in middle age.
Vertigo That Starts in the Brain
Not all vertigo begins in the ear. Central vertigo originates in the brainstem, the cerebellum (the brain’s balance coordination center), or the nerve pathways connecting them. The most common cause in older adults with risk factors like high blood pressure, diabetes, or heart disease is reduced blood flow to these areas, essentially a small stroke or transient ischemic attack affecting the balance circuits. In younger adults, the leading cause shifts to conditions like multiple sclerosis, where the immune system strips the insulating coating from nerve fibers in the brain.
Vestibular migraine is another major source of brain-based vertigo and one of the most common causes of episodic vertigo overall. It produces spinning, nausea, vomiting, and heightened motion sensitivity in association with migraine headaches, though the vertigo can sometimes occur without a headache at all. Vestibular migraine tends to become less frequent with age, while other central causes become more common.
How Episode Length Points to the Cause
The duration of a single vertigo episode is one of the most useful clues to what’s causing it. BPPV episodes are brief, typically under a minute, triggered by specific head movements and then fading quickly. Meniere’s disease episodes last much longer, often several hours per attack. Vestibular neuritis produces a single, prolonged episode of severe vertigo lasting days, followed by weeks of gradual improvement. Vestibular migraine episodes vary widely but generally last minutes to hours and recur over time.
When Vertigo Signals Something Serious
Most vertigo is uncomfortable but not dangerous. The red flags that suggest a stroke or other neurological emergency are vertigo accompanied by additional symptoms: trouble speaking, weakness or numbness on one side of the body, vision changes, severe imbalance making it impossible to walk, or difficulty swallowing. Patients who present with significant imbalance have nearly four times the odds of having a stroke compared to those with simple dizziness alone. Older men with cardiovascular risk factors and any accompanying neurological symptoms carry the highest risk for a stroke-related cause.
How BPPV Is Confirmed
If your vertigo fits the pattern of BPPV, the standard diagnostic test is called the Dix-Hallpike maneuver. A clinician turns your head to one side and quickly lowers you from sitting to lying with your head hanging slightly over the edge of the table. If loose crystals are present in the posterior canal (the most commonly affected one), your eyes will begin making characteristic involuntary movements after a short delay, typically 2 to 5 seconds. These eye movements beat upward and rotate, last less than a minute, and diminish if the test is repeated. Focusing your eyes on a fixed point for about 10 seconds can suppress them entirely, which helps distinguish BPPV from central causes where eye movements behave differently. If the horizontal canal is suspected instead, a separate rolling test is used.