What causes dizziness?

Feeling dizzy can mean different things to different people. You may feel lightheaded, off balance or as though the room is spinning. And while dizziness can be unsettling, many common causes are temporary and treatable.

The way your dizziness feels, what triggers it and any other symptoms you have can offer clues about what’s causing it. Here’s what to know — and when dizziness needs prompt medical attention. 

What does dizziness feel like?

Dizziness generally falls into a few common patterns, according to Song Kim, M.D., a vascular neurologist with Sutter:

• Imbalance: Feeling unsteady or off balance, almost as if you’re standing on a rocking boat
• Lightheadedness: Feeling faint or as though you might pass out
• Vertigo: Feeling as though you or your surroundings are spinning

Identifying which sensation you’re experiencing can help your doctor narrow down the possible cause. 

Common causes of dizziness

Dizziness can have many causes, and most aren’t emergencies. Some common possibilities include:

• Anemia: Having too few healthy red blood cells can cause lightheadedness, fatigue and weakness
• Anxiety: Stress and anxiety can sometimes cause lightheadedness or a woozy feeling
• Blood pressure changes: A sudden drop in blood pressure, particularly when you stand up quickly, can make you feel lightheaded or faint
• Dehydration: Not getting enough fluids can reduce blood volume and contribute to dizziness or lightheadedness
• Inner ear conditions: Problems such as benign paroxysmal positional vertigo, or BPPV, can cause a spinning sensation, often triggered by changes in head position
• Low blood sugar: Hypoglycemia can cause dizziness, particularly in people with diabetes who take insulin or other glucose-lowering medications
• Medication: Some antidepressants, sedatives and blood pressure medications can cause dizziness

“Older patients are particularly susceptible to the effects of medications, especially blood pressure medications,” Kim says. “If the dosing is too high, then the resulting low blood pressure can cause them to feel dizzy.”

High blood pressure usually doesn’t cause dizziness on its own. In fact, most people with high blood pressure don’t have symptoms, though a sudden spike in blood pressure (hypertensive emergency) can present as headache, blurred vision and confusion. Medications used to lower blood pressure can sometimes lower it too much and cause lightheadedness or dizziness. 

When dizziness may be more serious

Less commonly, dizziness can be related to conditions that affect the heart, brain or nervous system.

For example, an irregular heartbeat or other heart condition may reduce blood flow to the brain and make you feel dizzy or faint. Neurological conditions such as multiple sclerosis and Parkinson’s disease can also affect balance.

Sudden vertigo can sometimes be a symptom of a stroke, particularly when it occurs with other neurological symptoms.

“Most cases of dizziness are caused by conditions other than stroke,” Kim says. “By and large, vestibular inner ear conditions contribute to vertigo in far higher proportions than an acute stroke.”

That means vertigo alone doesn’t necessarily signal a stroke. But sudden dizziness combined with changes in balance, vision, speech or coordination needs immediate attention. 

When dizziness is an emergency

Call 911 if sudden dizziness or vertigo occurs along with symptoms such as:

• Difficulty speaking or slurred speech
• Difficulty swallowing
• Double vision or other sudden vision changes
• New weakness or numbness
• Severe difficulty walking or maintaining balance
• Sudden loss of coordination

These can be warning signs of a stroke. The American Stroke Association similarly advises using B.E. F.A.S.T. — sudden balance problems, eye or vision changes, facial drooping, arm weakness and speech difficulty — as a reminder to call 911 immediately.

Kim notes that some posterior circulation strokes can also cause the classic “5 D’s”: dizziness, diplopia, dysarthria, dysphagia and dystaxia. These refer to sudden vertigo, double vision, slurred speech, difficulty swallowing and loss of coordination. 

When to talk to your doctor

If dizziness keeps coming back, lasts a long time or interferes with your daily activities, make an appointment with your doctor.

It can help to keep track of what the dizziness feels like, when it happens, how long it lasts and what you were doing when it started. Also note any new medications or other symptoms that occur at the same time.

Your doctor can use those details to help determine whether the cause may be related to your inner ear, blood pressure, medications or another health condition — and what treatment may help.