Vertigo happens when your brain receives conflicting signals about where your body is in space. It’s not a disease itself but a symptom, and the most common trigger is a mechanical problem inside the inner ear. In about half of all cases, a peripheral vestibular disorder is responsible, with the rest split among migraines, nerve inflammation, medications, and occasionally something more serious like a stroke.
How Your Balance System Works
Your brain relies on three inputs to keep you oriented: your inner ear, your eyes, and sensors in your muscles and joints. Inside each inner ear sit three small, fluid-filled tubes called semicircular canals. When you turn your head, the fluid shifts and bends microscopic hair cells lining the canals. Those hair cells convert the movement into nerve signals that travel to your brain along the vestibular nerve. Your brain cross-references that data with what your eyes see and what your muscles feel against the ground or a chair. When all three inputs agree, you feel stable. When they don’t, you feel like the room is spinning.
Loose Crystals in the Inner Ear (BPPV)
The single most common cause of vertigo is benign paroxysmal positional vertigo, or BPPV. It accounts for roughly 20% of vertigo cases in older adults and is the diagnosis doctors reach most often in primary care. The mechanism is surprisingly physical: tiny calcium carbonate crystals that normally sit in one part of the inner ear break loose and drift into one of the semicircular canals. Once there, they slosh around with head movements and send exaggerated motion signals to the brain. The result is brief but intense spinning, usually lasting less than a minute, triggered by rolling over in bed, looking up, or tilting your head.
Why the crystals come loose isn’t always clear. Head injuries, aging, and prolonged bed rest are known contributors. Sometimes it happens for no identifiable reason at all. The crystals can either float freely inside the canal or stick to a structure called the cupula, and the type of displacement affects how the vertigo behaves.
The good news is that BPPV responds well to a simple repositioning technique. During the Epley maneuver, a clinician guides you from a seated position to lying down with your head turned to one side, then through a series of slow head rotations designed to roll the crystals out of the canal. Studies show about 88 to 91% of people are symptom-free within one week, whether a clinician performs the maneuver or the patient learns to do it at home twice a day.
Fluid Buildup and Ménière’s Disease
Ménière’s disease produces vertigo through a completely different mechanism. The inner ear contains a fluid called endolymph, and in Ménière’s, pressure in that fluid builds up abnormally. The excess pressure eventually ruptures the thin membrane separating two inner ear fluids that have very different chemical compositions. When those fluids mix, they overwhelm the nerve receptors responsible for balance, creating a sudden imbalance in nerve firing that your brain interprets as violent spinning.
Ménière’s episodes are longer and more debilitating than BPPV, often lasting 20 minutes to several hours. They come with a recognizable cluster of symptoms: fluctuating hearing loss, a low-pitched roaring or ringing in the ear, a feeling of fullness or pressure in the ear, and the vertigo itself. The episodes tend to come and go unpredictably.
What causes the fluid buildup varies. Hormonal imbalances, autoimmune conditions like lupus or rheumatoid arthritis, infections, allergies, head trauma, and metabolic disturbances have all been linked to elevated endolymphatic pressure. In many people, no single cause is identified.
Nerve Inflammation From Infections
Viral infections can inflame the structures of the inner ear and produce vertigo that lasts days or even weeks. Two related conditions fall into this category. Vestibular neuritis affects the vestibular nerve itself, causing prolonged vertigo without significant hearing loss. Labyrinthitis affects the broader inner ear structure (the labyrinth), causing both vertigo and hearing loss. Both typically follow a viral illness, though bacterial infections can also be responsible.
The vertigo from these conditions is usually constant rather than triggered by position changes, and it tends to be most severe in the first few days before gradually improving as the brain compensates for the damaged signals.
Vestibular Migraine
Migraines can cause vertigo even without a headache. Vestibular migraine produces episodes of spinning or unsteadiness that may come with nausea, vomiting, sensitivity to motion, and sometimes temporary hearing changes. Different episodes in the same person can look quite different, which makes this condition tricky to pin down. Some people experience the vertigo before a headache, some during, and some with no head pain at all.
An added complication is that vestibular stimulation (motion, visual movement) can itself trigger migraine attacks, creating a cycle where dizziness and migraines feed each other.
Medications That Damage the Inner Ear
Certain medications are directly toxic to the delicate hair cells of the inner ear. This is called ototoxicity, and it can cause vertigo, hearing loss, or both. The drug classes most commonly responsible include certain IV antibiotics (particularly aminoglycosides like gentamicin and tobramycin), platinum-based chemotherapy drugs, and loop diuretics used to treat fluid retention. Even high doses of aspirin can temporarily affect inner ear function. Environmental exposures to mercury, lead, and carbon monoxide carry similar risks.
Ototoxic damage is sometimes reversible when the medication is stopped, but in other cases the hair cell destruction is permanent. The risk increases with higher doses and longer treatment courses.
When Vertigo Signals Something Serious
Most vertigo comes from the inner ear and, while unpleasant, isn’t dangerous. But vertigo can also originate in the brainstem or cerebellum, where it may signal a stroke or other neurological emergency. Emergency physicians use a set of eye movement tests to tell the two apart. In peripheral (inner ear) vertigo, the eyes drift in one consistent direction and the brain struggles to keep focus during quick head turns. In central (brain) vertigo, eye movements change direction when looking to different sides, and the eyes may be vertically misaligned.
Certain patterns raise concern: vertigo with no obvious positional trigger, new difficulty walking or coordinating movements, double vision, slurred speech, numbness on one side of the body, or a severe headache unlike any you’ve had before. These combinations suggest the problem is in the brain rather than the ear. Posterior circulation strokes, which affect the back of the brain, can mimic a simple inner ear problem in their early hours, which is why the distinction matters.
Other Contributing Factors
Beyond the major causes, vertigo can show up in a range of situations. Head injuries can dislodge the inner ear crystals responsible for BPPV or damage the vestibular nerve directly. Prolonged bed rest, especially after surgery, increases the risk of crystal displacement. Anxiety disorders sometimes produce dizziness that feels like vertigo, though the mechanism is different. Low blood pressure, dehydration, and blood sugar drops cause lightheadedness that people often describe as vertigo, even though the inner ear isn’t involved.
Age is itself a risk factor. The vestibular system gradually loses hair cells over a lifetime, and the crystals in the inner ear become more brittle and prone to breaking loose. This is one reason BPPV becomes increasingly common after age 50.