What If Blood Pressure is Too High or Too Low?

Measuring blood pressure at home leads to questions about odd readings. You may wonder what to do if you get a particularly high reading (hypertension¹) - or a particularly low one (hypotension). The answer is definitely: it depends.

Blood pressure can vary widely during the day. A blood pressure reading of 132/70 in the morning can be 150/90 in the afternoon - or vice versa. One of the benefits of using blood pressure monitors at home is to keep track of trends by taking blood pressure measurements over many days.

Not only does blood pressure fluctuate, blood pressure monitors are not perfect. Sometimes, even a high-quality machine will return an inaccurate result. The first thing you should do when your blood pressure monitor gives you an abnormally high or abnormally low reading is to take your blood pressure again. If the second reading is similar, then it may be necessary to seek medical attention.

Who Do I Call?

Whether or not you have a blood pressure monitor at home doesn't change the rules on when to call 911².

Don't assume that a low reading is always a good thing. Everyone knows that high blood pressure is bad, but in an emergency, a low blood pressure can be even worse.

Shock³, a life-threatening condition, is an example of a low blood pressure emergency.

Having the extra information available during an emergency is not a bad thing, but sudden changes in blood pressure aren't alarming unless the changes come with other symptoms. If all you have is an abnormal blood pressure reading, call your doctor to see if he or she wants you to come in to the office or go to the hospital.

Otherwise, with or without an abnormal blood pressure, here are some symptoms that you should call 911⁴ for:

• Headache
• Weakness or numbness (especially on only one side of the body)
• Chest pain
• Shortness of breath
• Confusion
• Dizziness or vertigo

Tell the 911 dispatcher and the emergency responders about your sudden change in blood pressure, but definitely don't wait for it.

Should I Measure Blood Pressure at Home?

There is no good answer to this question. Monitoring your blood pressure is between you and your doctor. You don't need a prescription to buy a blood pressure monitor, but the benefit of monitoring blood pressure at home is still up in the air. Definitions of hypertension⁵ (high blood pressure) are based on blood pressure measurements in a clinical setting. Monitoring blood pressures elsewhere may not be comparing apples to apples. There is still a lot of research happening in this area, but the results are conflicting and inconclusive so far.

To learn more about blood pressure, read the following:

• What is Blood Pressure?⁶
  Explains what blood pressure is and what the numbers mean.

• How is Blood Pressure Measured?⁷
  Explains how blood pressure machines work.

• Top 5 Automated Home Blood Pressure Monitors⁸
  Top picks for automated blood pressure monitors.