This story originally appeared on massgeneralbrigham.org

Nearly half of adults (47%) in the United States have high blood pressure, or hypertension, but it often doesn’t cause symptoms.

“That’s why it’s sometimes called the silent killer, because people can have it for a long time,” explains John F. Keaney Jr., MD, director of the cardiology clinical service at Mass General Brigham and a cardiologist who treats patients at Brigham and Women’s Hospital. In this article, Dr. Keaney describes how to achieve and maintain your target blood pressure.

What is blood pressure?

Blood pressure measures the force of blood pushing against the walls of your arteries, which bring blood from your heart to the rest of your body. It’s measured in two numbers:

1. Systolic: The pressure when your heart beats, or contracts
2. Diastolic: The pressure when your heart rests between beats

According to the American Heart Association, normal blood pressure is 120/80 mmHg, or 120 systolic over 80 diastolic. The unit used to measure blood pressure is millimeters of mercury or mmHg.

What is hypertension?

Hypertension is when your blood pressure is consistently higher than normal. Guidelines do vary, but the American Heart Association defines hypertension as when a patient has a blood pressure reading of 130 mmHg or higher systolic, or 80 mmHg or higher diastolic.

“Hypertension is incredibly common. It becomes more common as you get older, and is more common in people with diabetes and obesity,” says Dr. Keaney. If left untreated, it can cause serious health problems like heart attack, stroke, and arrhythmias. “It’s been proven without a doubt that if you’re able to get your blood pressure down, those things become less of a problem,” says Dr. Keaney.

How does hypertension affect your health?

Many organ systems are affected by high blood pressure. If hypertension is left untreated, it can lead to serious health problems like:

• Stroke
• Heart attack
• Heart failure and other forms of heart disease
• Kidney disease or failure
• Peripheral artery disease, which affects your legs and arms
• Vision loss
• Sexual dysfunction

Testing for high blood pressure

If you’re diagnosed with high blood pressure, your doctor may order other tests to look for the cause, including:

• Ambulatory monitoring (checking your blood pressure regularly over an extended period of time)
• Lab tests of your blood and urine
• Echocardiogram (using sound waves to look at the heart)
• Electrocardiogram (also called an ECG or EKG, this measures the heart’s electrical activity)

How to control your blood pressure

It’s helpful to measure your blood pressure at home on a regular basis, especially if you already have hypertension. Blood pressure readings can be higher in the doctor’s office, due to nerves or anxiety. “If you are able to bring blood pressure readings to your doctor under your normal living conditions, that’s extremely valuable,” Dr. Keaney says. Blood pressure monitoring devices can be found at pharmacies or online. In some cases, your doctor may ask you to monitor your blood pressure remotely.

Lifestyle changes to control blood pressure

“One of the best ways you can get your blood pressure down is through lifestyle modification,” says Dr. Keaney. Here are changes you can make to your everyday habits:

• Exercise regularly. Aim for 150 minutes (2 hours and 30 minutes) of moderate-intensity activity a week.
• Maintain a healthy weight.
• Reduce salt intake. Try to get less than 1,500mg of sodium a day.
• Stop smoking.
• Limit alcohol.
• Get enough sleep (aim for at least 7 hours a night).
• Reduce stress.

Lifestyle changes don’t have to be extreme to make a difference. “You don’t have to join a gym; you don’t have to buy any special equipment. If you can walk briskly 30 minutes a day, five times a week, you can get all the benefit you need from exercise. You don’t have to start marathon running,” Dr. Keaney explains.

When to take blood pressure medication

Some patients may still need medication to manage their blood pressure. “If you have more complicated high blood pressure, such as you also have diabetes, you may need to be on more than one medicine,” says Dr. Keaney. Medications can lower blood pressure in several different ways:

• Getting rid of excess water and salt in your body
• Relaxing your heart vessels
• Reducing the force of your heart beat
• Blocking nerve activity that can restrict your blood vessels

Even with medication, lifestyle changes are always recommended. “Lifestyle modification makes it easier to reach the goal, even if you have to use medication,” Dr. Keaney explains. “You’ll get more bang for the buck for your medications.”