High blood pressure is one of the main drivers of heart disease and stroke. Nearly half of U.S. adults have high blood pressure, and about 1 in 4 people with hypertension has it under control. That means millions of people are living with quiet but serious strain on their heart, brain and blood vessels.

Updated guidelines from leading heart organizations now define high blood pressure as 130/80 mm Hg or higher or being on medication for hypertension. The lower threshold is based on strong evidence that even modestly higher numbers raise the risk for heart attack, stroke and kidney disease.

Lowering the definition of high blood pressure to 130/80 mm Hg does not mean everyone needs medicine sooner. Instead, it helps people and their care teams spot problems earlier and talk about lifestyle changes or treatment before damage builds up.

The newer guidelines aim to:

• Catch high blood pressure earlier, when it is easier to control.
• Encourage home blood pressure monitoring so readings reflect your everyday life.
• Highlight how diet, physical activity, weight, smoking and stress affect your numbers.
• Guide decisions about when to add or adjust blood pressure medicines.

Blood pressure is written as two numbers: systolic (top) over diastolic (bottom), measured in millimeters of mercury (mm Hg). Your category is based on the higher of the two numbers.

What to know about these categories:

• Even “elevated” blood pressure raises your risk over time and is a signal to make heart-healthy changes.
• Stage 1 and Stage 2 hypertension usually need a mix of lifestyle changes and, for many people, medication.
• A hypertensive crisis is a medical emergency — call 911 if very high numbers occur with concerning symptoms such as chest pain, shortness of breath, weakness or vision changes.

The new guidelines put more focus on knowing your numbers and acting early. A few practical steps can make a big difference:

Know and track your numbers:

• Get your blood pressure checked at least once a year, or more often if your doctor recommends it.
• Use a validated home monitor and bring it to appointments to compare readings.
• Keep a simple log of readings, noting the date, time and how you were feeling.

Build heart-healthy habits:

• Follow an eating pattern rich in fruits, vegetables, whole grains and lean proteins, with less sodium and added sugar.
• Aim for at least 150 minutes of moderate physical activity each week, such as brisk walking.
• Maintain a healthy weight, quit smoking and limit alcohol if you drink.
• Take blood pressure medicines exactly as prescribed — do not stop without talking to your clinician.