Why does my blood pressure reading keep changing?

Heart Health
Feb 16, 2023

St. Joseph’s/Candler clinical pharmacist explains reasons why your blood pressure numbers may fluctuate and if you should seek treatment

Have you ever had your blood pressure checked and it was suddenly elevated or high, but a month later at another doctor’s appointment, your blood pressure was normal?

That’s because blood pressure readings can fluctuate, so much so that your reading can be different even hours apart.

So if it’s elevated all of the sudden, there may be no need to panic. But everyone should take blood pressure seriously as ignoring ongoing high blood pressure – also called hypertension – can lead to complications as serious as heart attack or stroke.

“A lot of people don’t know when their blood pressure is high. You can be very asymptomatic and feel fine but on the inside your pressure is rising and continuing to put you at high risk of sudden complications,” says Melissa Johnson, clinical pharmacy specialist for St. Joseph’s/Candler’s Center for Medication Management. She also sees patients at our Pooler Primary Care office, and Johnson counsels St. Joseph’s/Candler co-workers in our WellPath Hypertension Program.

What is blood pressure?

Blood pressure is the force of blood pushing against the walls of your arteries, which results from the heart pumping blood through the circulatory system. Our arteries carry blood away from the heart to organs and tissues throughout our body while our veins carry the blood back to the heart.

We need some amount of pressure in order to circulate blood, but if that pressure gets too high it means your heart is working against a higher force than it would normally need to, Johnson says.

So ideally you want a blood pressure reading of 120/80 (read: 120 over 80) or lower. The top number is the systolic pressure, which is the amount of pressure in your arteries when your heart muscle is contracting, or pushing the blood out to the rest of your body, Johnson explains. The bottom number is the diastolic pressure, or the amount of pressure in your arteries when your heart is at rest.

When these numbers are in a higher range than 120/80, blood pressure is considered to be elevated (120-129 and less than 80) to high (anything greater than 130 and 80). If systolic exceeds 180 and/or diastolic exceeds 120, it is considered a hypertension emergency requiring immediate care.

Related Article: Understanding your blood pressure reading

But why can it fluctuate?

If you have a reading that is elevated or even high, there may be no need to panic, Johnson says, especially if it’s the first time it’s read above normal. Blood pressure readings can fluctuate due to a number of reasons including:

  • Certain medications you may be on, especially if it contains a stimulant
  • Physical activity, even including taking the stairs or rushing to your appointment
  • Caffeine
  • Nicotine
  • Stress

There’s even something called White Coat Hypertension, in which a person’s blood pressure is only elevated at the doctor’s office due to stress or anxiety as opposed to checking it at home or on your own at a pharmacy.

“The best blood pressure reading is you sitting down, resting for at least five minutes, with your feet flat on the floor, back supported and not crossing your legs,” Johnson says.

How do you diagnose high blood pressure?

At each doctor’s appointment, whether you go once a year for a routine physical, or more often, you should ideally have your blood pressure checked. If you have an elevated or high blood pressure reading for the first time, it doesn’t mean you are diagnosed with high blood pressure, Johnson says. It takes more than one reading to make a diagnosis, she says.

However, your doctor may want you to come back sooner to check it again or ask you to check it at home and keep a log. Blood pressure cuffs are available at most pharmacies and some insurances cover the cost.

Your doctor also may suggest lifestyle modifications to control blood pressure with the two big ones being diet and exercise. Your diet should include lots of vegetables and fruits and very little salt – less than two grams a day for people who are watching their blood pressure.

They also recommend at least 150 minutes of moderate to intense exercise each week, so something that gets your heart pumping, Johnson says.

If you continue to have high blood pressure readings over the course of several visits, especially if you’ve made lifestyle modifications, your doctor and pharmacist may recommend blood pressure medication. There are many options, and your healthcare team will choose the best one for you depending on any other potential comorbidities or medicines you may be on, Johnson says.

Related Article: What causes high blood pressure?

The two big takeaways

“People do get one high result and tend to freak out sometimes, but like I said, it usually takes more than one reading to diagnose you,” Johnson says. “That being said, it is important to get your blood pressure regularly checked so we can watch for trends because if you do stay high, then we want to talk about long-term complications and preventing those.”

“The other big takeaway point is that most people with high blood pressure are asymptomatic, so you may feel fine, but your body is struggling inside with all that high pressure built up and your risk of heart attack and stroke goes up significantly. You don’t want to ignore checking your blood pressure.”

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