Prehypertension is between 120-139 for the first number in your blood pressure reading, and/or 80-89 for the second number. Nearly 30% of American adults have prehypertension, according to the CDC.
What's the risk? You're more likely to get high blood pressure (hypertension).
Also, you may be more likely to have a stroke if your blood pressure is in the upper end of the prehypertension range and you're younger than 65, one study shows.
Even if your prehypertension isn't that high, it's still tough on your body. "It's causing the heart muscle to beat against a higher pressure, so [the heart] is becoming thicker," says Richard Stein, MD, who directs the exercise, nutrition, and cardiovascular program at New York University's Center for Prevention of Cardiovascular Disease.
Prehypertension and hypertension are on the rise. They've become more common as the U.S. has become more obese and inactive, Stein says. You're also more likely to get prehypertension if you have diabetes, high cholesterol, or a family history of high blood pressure, Stein says.
Prehypertension is a particular problem among African-Americans. Researchers have reported that African-Americans with prehypertension develop high blood pressure a year sooner than Caucasians. The reasons for that aren't known.
Prehypertension, like hypertension, doesn't show signs or symptoms. How do you know if you have it? The only way to know is to check your blood pressure, Stein says. You can take your blood pressure at your doctor's office, at home with a blood pressure monitor, or by using a blood pressure machine at your local pharmacy or grocery store.
If you're healthy and your top or bottom blood pressure number is above normal, wait 2 or 3 days and check it again. If it's still higher than normal, tell your doctor so you can start getting it under control.