Blood Pressure Numbers: When to Get Help

British Columbia Specific Information

High blood pressure, also called hypertension, can damage your blood vessels, heart and kidneys. This damage can cause a heart attack, stroke or other health problems. Your blood pressure reading is based on two measurements called systolic and diastolic. The systolic (top number) and diastolic (bottom number) are written as a ratio, for example (120/80 mmHg). A reading of more than 140/90 mmHg taken at your healthcare provider’s office may indicate high blood pressure. This figure is different for people with diabetes whose blood pressure should be below 130/80 mmHg. People suffering from other illnesses will have different target normal values. For more information on hypertension, visit the Heart & Stroke Foundation and Hypertension Canada.

Healthy lifestyle choices can help lower your blood pressure and improve your health. For information on healthy eating for lowering your blood pressure, see:

You may also call 8-1-1 to speak to a registered dietitian, Monday to Friday 9:00 a.m. to 5:00 p.m., or you can Email a HealthLinkBC Dietitian.

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 and 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.

Health Tools

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High Blood Pressure: Checking Your Blood Pressure at Home

References

Citations

Leung AA, et al. (2017). Hypertension Canada's 2017 guidelines for diagnosis, risk assessment, prevention, and treatment of hypertension in adults. Canadian Journal of Cardiology , 33(5): 557–576. DOI: 10.1016/j.cjca.2017.03.005. Accessed December 28, 2017.

Other Works Consulted

Whelton PK, et al. (2017). Guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Journal of the American College of Cardiology, published online November 13, 2017. DOI: 10.1016/j.jacc.2017.11.006. Accessed November 20, 2017.