Overview
What do your blood pressure numbers mean?
Blood pressure is a measure of how hard the blood pushes against the walls of your arteries as it moves through your body. Blood pressure readings include two numbers. The top (systolic) number shows how hard the blood pushes when the heart is pumping. The bottom (diastolic) number shows how hard the blood pushes between heartbeats
It's normal for blood pressure to go up and down throughout the day. If the top number is regularly 120 or higher or the bottom number is regularly 80 or higher, this is either elevated blood pressure or high blood pressure (hypertension). Your doctor may want you to monitor your blood pressure at home to see how your blood pressure is over time.
Most medical guidelines say a normal blood pressure measurement is less than 120/80 mmHg. Your doctor will give you a goal for your blood pressure. Your goal will be based on your health and age. If you have high blood pressure, your doctor will work with you on lifestyle changes and using medicines to lower your blood pressure.
In general, the lower your blood pressure, the better. For example, a blood pressure reading of less than 90/60 is healthy as long as you feel okay.
What can cause blood pressure to go up or down?
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 your blood pressure to go up. These medicines include certain asthma medicines and cold remedies.
A low blood pressure reading can be caused by many things, including a severe allergic reaction or an infection. Another cause is dehydration, which is when your body loses too much fluid. Some medicines, such as diuretics and some antidepressants, can cause your blood pressure to go down.
When should you call your doctor?
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 your usual 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 usual (such as 180/120 or higher).
- You think high blood pressure is causing symptoms such as:
- Severe headache.
- Blurry vision.
- You are dizzy or lightheaded, or you feel like you may faint.
Watch closely for changes in your health, and be sure to contact your doctor if:
- Your blood pressure measures higher or lower than your doctor recommends when you measure it at least 2 times a few minutes apart. That means the top number or the bottom number is out of your recommended range, or both numbers are.
- You think you may be having side effects from your blood pressure medicine.
