There’s a reason why high blood pressure (clinically called “hypertension”) is known as the “silent killer.” Until dangerously high, it has very few (if any) noticeable symptoms. Over time, high blood pressure can damage arteries in the heart or brain without any warning until a patient experiences a heart attack or stroke, warns Miguel A. Salazar Jr., M.D., a California-based cardiovascular disease specialist.

Considering nearly one in three American adults has high blood pressure, we all need to keep the health consequences in mind. Here’s what experts want you to know.

What Happens When You Have High Blood Pressure

When blood pressure is high, your blood vessels—which carry oxygen and nutrients to your vital organs, including your heart—become damaged. Over time, your blood vessels thicken, which makes them more susceptible to tears and ruptures, says Nicole Weinberg, M.D., cardiologist at Providence Saint John’s Health Center in Santa Monica.

“Having a lack of elasticity is not good for your blood vessels, since they need to expand and contract to function well,” Weinberg adds.

Though high BP most commonly affects the heart and kidneys, no part of the body is safe from its impact.

Conditions That Can Result from High Blood Pressure

If left unchecked, high BP can put a number of your body systems in danger. Typically, it contributes to a handful of incredibly serious issues.

1. Stroke

Over time, high blood pressure can lead to stroke, during which blood flow to part of the brain becomes cut off. “The elevated pressure can cause a sudden burst in the vessels in the brain, leading to hemorrhagic stroke,” says Dr. Sanjiv Patel, M.D., cardiologist at MemorialCare Heart & Vascular Institute at California’s Orange Coast Medical Center. “Or, deprivation of blood flow in the brain because of narrowed arteries can cause several mini strokes.”

Though stroke symptoms can vary, they typically include headaches and blurry vision and/or sudden numbness or weakness on one side of the body.

2. Heart Attack

High blood pressure can cause thickening of the arteries around the heart muscle, which requires your body to work harder and harder to keep blood flowing. According to Patel, this limited blood flow to the heart inevitably leads to a heart attack.

Read More: No, You’re Not Too Young To Have A Heart Attack

“Symptoms of a heart attack can include chest pain, pressure, or heaviness, shortness of breath, and neck pain, among other things,” he says. However, symptoms can vary between men and women, who are more likely to experience nausea and back or jaw pain.

3. Kidney Failure

High blood pressure affects tiny blood vessels in a microscopic unit of the kidneys that regulates water and filters blood (called the nephron), says Salazar. This contributes to kidney failure, in which the organs can’t properly filter blood. As a result, blood’s electrolyte content becomes imbalanced. “This leads to fatigue, water retention and swelling, shortness of breath, and increased risk of heart attack and stroke,” says Patel.

4. Blindness

Though less common than heart attacks, strokes, and kidney issues, high blood pressure can also impact your eyesight. “The tiny blood vessels of the retina can become cut off or detached, leading to blindness,” Salazar says.

Monitoring Your Blood Pressure

Your primary care provider should always check your blood pressure at the beginning of your annual check-up. (Doctors typically check it during all appointments, though.)

When your doctor puts that cuff around your arm, they’re actually checking two things:

• your systolic blood pressure, which measures the pressure in your blood vessels when your heart beats
• your diastolic blood pressure, which measures the pressure in your blood vessels when your heart relaxes between beats

If your doctor says your BP is 120/80 (which is normal, by the way), the “120” is your systolic blood pressure, while the “80” is your diastolic blood pressure, explains Texas-based cardiologist Waqar Khan, M.D.

A systolic reading above 130 is considered high, adds Salazar. Anything above 180 (known as hypertensive urgency) is considered dangerous. 

As long as you visit the doctor regularly, you should have a general understanding of whether your BP is healthy or not.

How To Maintain Healthy Blood Pressure

The number one way to prevent high BP and the dangerous medical conditions it can cause: living a healthy, active lifestyle.

Salazar recommends incorporating daily exercise—which increases nitric oxide, a chemical that helps maintaining blood vessel elasticity—into your routine. When it comes to diet, he says to limit your salt intake as much as possible. (The Dietary Guidelines for Americans recommends less than 2,300 mg per day.) In addition to increasing fluid retention, excess salt can also increase blood pressure.

Read More: 5 Nutrients That Are Good For Your Heart—Other Than Fish Oil

Of course, you’ll also want to curb unhealthy lifestyle habits, such as smoking and excessive use of caffeine or alcohol, which can also impact BP.

If your doctor notices high blood pressure, they may recommend that you purchase a machine so you can monitor your levels at home to ensure they don’t increase. As with any chronic health condition, work closely and honestly with your healthcare providers to ensure you’re taking all of the necessary steps to ward off high BP and protect your long-term health.

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