What You Should Know About Low Blood Pressure

Maybe you stand up too quickly or you haven’t eaten in a while and suddenly you're feeling dizzy or off balance. You’re lightheaded. Sometimes, lightheadedness isn’t anything to worry about. But other times, it could be a sign that something is wrong.

Lightheadedness is a common symptom that can happen for many reasons, including low blood pressure (hypotension), dehydration or sudden changes in position. Understanding what causes lightheadedness can help you know when it’s harmless and when to seek care.

What is low blood pressure?

“Blood pressure is a measure of the force on the walls of the arteries when the heart pumps blood into them,” said Hassan Beydoun, MD, a cardiologist with Banner – University Medicine.

Hypotension is when this force is too low. With hypotension, your organs might not get enough blood.

You have two measurements that tell you what your blood pressure is. The pressure when your heart beats is the first or top number, called systolic. The pressure when your heart is at rest between beats is the second or bottom number, called diastolic.

Blood pressure is measured in millimeters of mercury (mmHg). A normal blood pressure reading is around 120/80 mmHg. “Low blood pressure is less than 90/60 mmHg, or when you have an exaggerated drop in blood pressure and increase in heart rate when you stand up,” Dr. Beydoun said.

What does lightheadedness feel like?

Lightheadedness can feel different from person to person. Some people describe it as:

Feeling faint or like you might pass out
A sudden “head rush” when standing up
Feeling unsteady or off balance
Blurred or dim vision
Weakness or shakiness

Lightheadedness is not always the same as dizziness. Dizziness may feel like the room is spinning, while lightheadedness often feels more like you might faint.

Symptoms of hypotension

Symptoms of low blood pressure include:

Dizziness and lightheadedness: Feeling that the world around you is swaying or you aren’t steady on your feet. You may feel disoriented. “Low blood pressure causes lightheadedness simply because not enough blood and oxygen is reaching the brain,” Dr. Beydoun said.
Fatigue and weakness: Your organs and muscles might not get enough oxygen, so you might feel tired or weak even when you haven’t exerted yourself very much.
Fainting or almost fainting: Called syncope, you can faint or nearly faint when your brain doesn’t get enough blood flow or oxygen.

Causes of hypotension and lightheadedness

Different things can be making your blood pressure low or making you feel lightheaded.

Common everyday causes

Fast position changes: Orthostatic hypotension or postural hypotension happens when you stand up quickly and your blood pressure drops.
Dehydration: When your body doesn’t have enough fluid, you don’t have as much blood volume, which can lower your blood pressure.
Low blood sugar: A drop in blood glucose levels can cause lightheadedness.

Medical causes

Heart problems: An extremely low heart rate (bradycardia) or heart valve problems can prevent your heart from pumping blood effectively and cause hypotension.
Heart-brain miscommunication: Neurally mediated hypotension happens when your heart and brain don’t communicate properly.
Disorders affecting the endocrine system: Conditions like adrenal insufficiency (Addison’s disease) or low thyroid function (hypothyroidism) may cause hypotension.
Low iron levels in your blood: Anemia can keep your cells and organs from getting the oxygen they need.

Other possible causes

Severe infection (septicemia): Blood infection can cause inflammation that can affect your blood vessels and lead to low blood pressure.
Blood loss: Losing a lot of blood due to injury, surgery or a medical condition can quickly lead to hypotension.
Anxiety or panic attacks: Your breathing rate at these times can cause lightheadedness.
Side effects of some medicines: Medications for some health conditions can cause hypotension.
Heart attack, heart failure or stroke: These serious conditions can lower your blood pressure.
Inner ear problems: Your inner ear manages your balance, so problems can cause dizziness and lightheadedness.

Diagnosing hypotension

If you feel lightheaded sometimes, it might not be anything to worry about. But if your symptoms are more serious, talk to a health care provider.

“You should see a provider if you have dizziness, fainting, lightheadedness, blurred vision, palpitations, confusion, nausea or general weakness,” Dr. Beydoun said. It’s important to seek care if your symptoms make it hard to do your daily activities or affect your quality of life.

To diagnose hypotension, your provider may:

Ask you about your symptoms, medical history and lifestyle.
Monitor your blood pressure to see how it changes throughout the day.
Evaluate the electrical activity of your heart with an electrocardiogram.
Record your heart activity for a longer time with a Holter monitor, which may catch problems that don’t show up in a short exam.
Test your blood for hormone levels, signs of infection and organ function.
Perform a tilt table test, which checks how your blood pressure changes when you shift from a lying to a standing position.

When should you worry about lightheadedness?

Most cases of lightheadedness are not serious. But you should get medical care right away if you have:

Chest pain
Shortness of breath
Confusion
Loss of consciousness
Severe injury or bleeding

These symptoms could be signs of a more serious condition that needs immediate attention.

Lifestyle changes

You can take some steps to manage hypotension:

Stay hydrated since dehydration can cause low blood pressure and make you feel lightheaded. Drink plenty of water, especially if you’re exercising or you’re outside in hot weather.
Eat small, low-carb meals to keep your blood sugar levels stable.
Add more salt to your diet.
When you stand up from sitting or lying down, go slowly. “That gives your body time to adjust to the change in position,” Dr. Beydoun said.
Wear compression stockings to help the blood circulate up from your legs.
Avoid alcohol and too much caffeine, which can cause a drop in blood pressure.
Get regular exercise to help keep your cardiovascular system healthy.
If possible, stop taking medications that are causing low blood pressure. Talk to your health care provider before stopping any medications.

Treatment options

Depending on what’s causing your low blood pressure, your provider may recommend treatments in addition to lifestyle changes. Some options are:

Medications to regulate blood pressure and treat conditions that could be causing low blood pressure, such as fludrocortisone, midodrine and erythropoietin.
Treatment for heart conditions.
Managing endocrine disorders like adrenal insufficiency or hypothyroidism.
Treating infections like septicemia.

Frequently asked questions about lightheadedness

Why do I feel lightheaded when I stand up?

This is often caused by a sudden drop in blood pressure, known as orthostatic hypotension. It happens when your body doesn’t adjust quickly enough to a change in position.

Is lightheadedness the same as dizziness?

Not exactly. Lightheadedness often feels like you might faint, while dizziness can feel like the room is spinning.

Can dehydration cause lightheadedness?

Yes. When you are dehydrated, your blood volume drops, which can lower your blood pressure and make you feel lightheaded.

When should I see a doctor for lightheadedness?

You should see a provider if your symptoms happen often, affect your daily life or come with symptoms like fainting, chest pain or confusion.

The bottom line

If you have low blood pressure - less than 90/60 mmHg or a big drop in blood pressure when you stand up - it could cause lightheadedness and other symptoms, including feeling dizzy or faint. If it happens once in a while, it’s probably not a cause for concern. But if it’s affecting your life or you have other symptoms, you’ll want to see a health care provider.

Reach out to Banner Health to connect with a provider who can diagnose and treat lightheadedness and hypotension.

Have you listened?

Understanding Lightheadedness: Could It Be Hypotension?