Topic Overview

If you check your blood pressure, you may wonder when an abnormal reading means you should call your doctor. This information can help you understand what your blood pressure numbers mean and when you need to call for help.

What do blood pressure numbers mean?

Your blood pressure consists of two numbers: systolic and diastolic. Someone with a systolic pressure of 117 and a diastolic pressure of 78 has a blood pressure of 117/78, or "117 over 78."

Blood pressure that is too high increases your risk for heart attack and stroke. Your blood pressure should be less than 140/90 ("140 over 90"). If you have diabetes it should be less than 130/80 ("130 over 80"). If you are 80 years old or older, it should be less than 150/90 ("150 over 90").

If the first (systolic) number is: OR the second (diastolic) number is: Your blood pressure has:
120 or less 80 or less Low risk (ideal)
121 to 139 81 to 89 Medium risk (high-normal)
140 or more 90 or more High risk (hypertension)

In general, the lower your blood pressure, the better. A blood pressure reading of less than 90/60 is normal as long as you feel okay.

What can cause a short-term change in blood pressure?

It's normal for blood pressure to go up and down throughout the day. Things like exercise, stress, and sleeping can affect your blood pressure. Some medicines can cause a spike in blood pressure, including certain asthma medicines and cold remedies.

A low blood pressure reading can be caused by many things, including some medicines, a severe allergic reaction, or an infection. Another cause is dehydration, which is when your body loses too much fluid.

When should you get help for an abnormal blood pressure reading?

One high or low blood pressure reading by itself may not mean you need to call for help. If you take your blood pressure and it is out of the normal range, wait a few minutes and take it again. If it's still high or low, use the following guidance.

Call 911 anytime you think you may need emergency care. For example, call if:

  • You passed out (lost consciousness).

Call your doctor now or seek immediate medical care if:

  • Your blood pressure is much higher than normal (such as 180/110 or higher).
  • You think high blood pressure is causing symptoms such as:
      • Severe headache.
      • Blurry vision.
      • Shortness of breath.
      • Chest pain.
      • Anxiety.

Call a doctor if:

  • Your blood pressure is 140/90 or higher on two or more occasions.
  • Your blood pressure is usually normal and well controlled, but it goes above the normal range on more than one occasion.
  • Your blood pressure is lower than usual and you are dizzy or light-headed.
  • You think you may be having side effects from your blood pressure medicine.

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References

Other Works Consulted

  • Daskalopoulou S, et al. (2015). The 2015 Canadian hypertension education program recommendations for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension. Canadian Journal of Cardiology, 31: 549-568.
  • Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (2003). Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure JNC Express (NIH Publication No. 03-5233). Bethesda, MD: U.S. Department of Health and Human Services.

Credits

Adaptation Date: 12/3/2017

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC

Adaptation Date: 12/3/2017

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC