Sudden dizziness paired with nausea usually comes from your inner ear, a drop in blood pressure, or low blood sugar. These are the most common culprits, and most of them are treatable or resolve on their own. Less commonly, the combination signals something that needs urgent attention, like a stroke or carbon monoxide exposure. Understanding what else is happening in your body alongside the dizziness helps narrow down the cause.
Loose Crystals in Your Inner Ear (BPPV)
The single most common cause of sudden, intense dizziness is a condition called BPPV. Tiny calcium crystals normally sit inside a part of your inner ear called the utricle, where they help your brain track your head’s position relative to gravity. Sometimes these crystals break loose and drift into the semicircular canals, fluid-filled tubes that detect rotation. Once there, the crystals can’t dissolve, and they send false signals to your brain every time you move your head.
The result is a spinning sensation that hits hard and fast, often with nausea, triggered by specific head movements: tipping your head back, rolling over in bed, sitting up quickly, or tilting your head to one side. Each episode typically lasts less than a minute, but the nausea can linger. BPPV can start for no obvious reason, though it’s more common after a head injury, prolonged bed rest, or simply with age.
The good news is that BPPV is very treatable. A healthcare provider can perform a repositioning maneuver (often called the Epley maneuver) that guides the loose crystals back where they belong. The sequence involves turning your head 45 degrees toward the affected ear, lying back quickly, then slowly rotating your head and body through a series of positions, holding each for about 20 to 30 seconds. Many people feel significantly better after just one or two sessions. The American Academy of Otolaryngology specifically recommends repositioning maneuvers over medications for BPPV, noting that anti-dizziness drugs are often prescribed inappropriately for this condition.
Inner Ear Inflammation
If your dizziness came on suddenly and has been constant for hours or days rather than triggered by movement, an inflamed inner ear nerve is a likely explanation. Vestibular neuritis is inflammation of the balance nerve, usually triggered by a viral infection. It causes severe vertigo, nausea, vomiting, and difficulty with balance, but your hearing stays normal. The initial episode can last hours to days, followed by weeks to months of lingering unsteadiness as your brain recalibrates.
Labyrinthitis involves inflammation deeper in the inner ear, affecting both the balance and hearing structures. It produces the same vertigo and nausea but adds hearing loss or ringing in one ear. The hearing loss from labyrinthitis is often permanent, which makes it worth paying attention to whether your hearing feels off alongside the dizziness. Both conditions typically improve on their own, though full recovery of balance function varies from person to person.
Blood Pressure Drops When You Stand
If the dizziness and nausea hit specifically when you stand up, your blood pressure may be dropping too fast. This is called orthostatic hypotension, defined as a drop of 20 mmHg or more in the upper blood pressure number (or 10 mmHg in the lower number) within a few minutes of standing. Your brain briefly doesn’t get enough blood flow, producing lightheadedness, nausea, and sometimes graying vision.
Common triggers include dehydration, skipping meals, hot weather, alcohol, standing up after sitting or lying down for a long time, and certain medications (especially blood pressure drugs and antidepressants). It’s also more frequent in older adults. If this sounds like your pattern, drinking more fluids, standing up slowly, and avoiding prolonged standing in heat can make a meaningful difference.
Low Blood Sugar
When blood glucose drops below about 70 mg/dL, dizziness and nausea are among the first symptoms to appear. You’ll usually also notice shakiness, sweating, hunger, irritability, or a fast heartbeat. This can happen to anyone who hasn’t eaten in a while, exercised hard without fueling up, or consumed a lot of alcohol on an empty stomach. People with diabetes who take insulin or certain oral medications are at higher risk, but it also affects people without diabetes.
If you suspect low blood sugar, eating or drinking something with fast-acting carbohydrates (juice, glucose tablets, a few pieces of candy) typically brings relief within 10 to 15 minutes. If episodes keep happening without an obvious explanation, that’s worth investigating with a doctor.
Vestibular Migraine
Migraine doesn’t always mean a headache. Vestibular migraine causes episodes of moderate to severe dizziness, often with nausea, that can last anywhere from five minutes to 72 hours. About 30% of people with this condition have episodes lasting minutes, 30% lasting hours, and another 30% lasting several days. Some people experience only brief seconds-long attacks that repeat with head motion or visual stimulation. Full recovery from a single episode can take up to four weeks in some cases.
You’re more likely to have vestibular migraine if you have a history of migraine headaches, but the dizziness episodes don’t always come with head pain. Sensitivity to light, sound, or visual motion during the episode is a clue. If your sudden dizziness comes in recurring bouts and you have a migraine history, this is a strong possibility to discuss with your doctor.
Ménière’s Disease
Ménière’s disease causes episodes of vertigo lasting 20 minutes to 12 hours, paired with fluctuating hearing loss (especially in lower-pitched sounds), ringing or roaring in one ear, and a feeling of fullness or pressure in that ear. Some people have attacks separated by long stretches of normalcy; others get clusters of attacks over several days.
A diagnosis requires at least two spontaneous vertigo episodes with documented hearing changes. If your dizziness comes with noticeable ear symptoms, particularly on one side, Ménière’s is worth considering.
Other Common Triggers
Several everyday situations can produce sudden dizziness and nausea without an underlying disease. Dehydration is one of the most overlooked: losing even a small percentage of your body’s water volume reduces blood volume and can trigger lightheadedness and stomach upset. Heat exposure, intense exercise, illness with vomiting or diarrhea, and simply not drinking enough water are frequent causes.
Anxiety and panic attacks can also produce sudden dizziness, nausea, a racing heart, and a feeling of unreality. The symptoms are real and physical, driven by your body’s stress response, even when there’s no structural problem with your inner ear or brain. Carbon monoxide poisoning is a rarer but dangerous cause that mimics flu-like symptoms: dizziness, nausea, headache, weakness, and confusion. If multiple people in the same building feel sick simultaneously, get outside immediately and call emergency services.
When Dizziness Signals an Emergency
Most causes of sudden dizziness and nausea are not dangerous, but a few are. A stroke can present as sudden dizziness, loss of balance, and nausea, sometimes without any classic signs like arm weakness or slurred speech. The BEFAST screening tool is useful here: Balance problems, Eyes (vision changes), Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services. If your dizziness came with any combination of difficulty walking, double or blurred vision, facial drooping, one-sided weakness, confusion, or the worst headache of your life, call emergency services immediately.
Persistent vomiting alongside dizziness also warrants emergency evaluation, as does dizziness after a head injury. These situations are uncommon, but recognizing them quickly makes a significant difference in outcomes.