6 Surprising Reasons Your Blood Pressure Spikes

Seemingly harmless situations can temporarily raise your blood pressure. Here’s how to make sure your reading is accurate.

You probably know someone with high blood pressure.

Among people 65 and older, at least 75 percent meet the criteria for hypertension or high blood pressure, defined as a blood pressure reading greater than 130/80 mmHg, according to the American Heart Association.

Uncontrolled high blood pressure can lead to serious health issues throughout your whole body, including heart attack, stroke, kidney disease, vision loss, and diabetes complications. So if your blood pressure begins to run high, it’s vital to work with your doctor to get it under control.

But how do you know if your blood pressure is actually a problem?

If you get a higher-than-normal reading, the first thing you should do is make sure it’s actually indicative of what your blood pressure really is, since there are some behaviors and situations that can elevate it temporarily, says John Bisognano, M.D., Ph.D., director of the University of Rochester Comprehensive Hypertension Center.

You can do that by doing two things:

• Make sure the reading is taken properly and accurately. Sit with your legs uncrossed and feet flat on the floor, and take your reading after sitting and resting quietly for five minutes
• Check your blood pressure regularly at home. By recording all of the readings, not just the highs or lows, you’ll get a more complete picture of your blood pressure to share with your doctor.

Regularly checking your blood pressure at home also means you’ll be more likely to spot an anomaly that may be due to factors that can temporarily cause blood pressure spikes. Here are six such examples.

Blood-Pressure Booster #1: You Drank a Lot of Caffeine

A big cup of coffee can bring a wake-up-now jolt, so it’s not surprising that caffeine can give your blood pressure a boost too. What you may not know is that the type of coffee you’re drinking can play a role in upping your readings.

Caffeine levels vary widely in different kinds of coffees and with different roasting techniques, Dr. Bisognano says, and blood pressure can spike up to 20 mmHg after drinking kinds with more caffeine.

For instance, take Starbucks coffee. A tall size of brewed dark roast contains 193 milligrams of caffeine, but the same size of blonde roast has 270 milligrams.

Also, pay attention to the sizes you’re drinking. A regular mug you brew at your house may be just eight ounces, but if you’re grabbing coffee on the run, you may pick up one that’s twice as large—which means twice as much caffeine.

To be safe, finish your coffee more than one hour before you’re set to take your blood pressure.

Blood-Pressure Booster #2: You Have to Pee

According to a 2017 review in the Journal of Hypertension, getting your blood pressure taken with a full bladder can lead to an inaccurate reading. Drinking large amounts of fluids within an hour of a test can lead to a 33 mmHg bump in systolic pressure or the top number, and a 19 mmHg bump in diastolic pressure or the bottom number.

“First of all, it’s uncomfortable, and whenever someone is uncomfortable, their blood pressure goes up,” Dr. Bisognano says. “There are also nerves in the bladder that, when activated, can raise blood pressure.”

Play it safe and make a pit stop at the bathroom before you get a reading done.

Blood-Pressure Booster #3: You Ate a Salty Meal

An overall high-salt diet can lead to the development of hypertension. But even one high-salt meal can cause a temporary jump in blood pressure, says Karen Alexander, M.D., a professor of cardiology at Duke University School of Medicine.

“A high-salt meal causes you to hold on to more water,” she explains. That can be a problem, since blood vessels tend to get stiffer and less flexible with age. These “stiff pipes” can’t stretch as well to accommodate the extra volume, and your blood pressure can increase.

Restaurant meals tend to be high in sodium and can lead to a reading about 10 mmHg higher than normal, Dr. Alexander says. This may last between 24 to 48 hours and should go back to baseline after you start eating a more normal diet—preferably one high in fruits and vegetables.

Blood-Pressure Booster #4: Your Arthritis Is Flaring

Any kind of pain can lead to an increase in blood pressure—and the more intense the pain, the more your blood pressure can rise, Dr. Alexander says.

It all comes down to something called catecholamines, which are a type of stress hormone.

“When you are in pain, your catecholamines and stress hormones are high, and that acts on blood vessels and raises blood pressure,” she explains. Depending on the amount of pain, you can see increases in your blood pressure of 10 to 20 mmHg.

If you have an acute injury and your blood pressure is running high, your doctor should work with you to get the pain under control and then check your blood pressure again to get a more accurate reading.

Blood-Pressure Booster #5: You’re Stressed

“White coat hypertension” refers to blood pressure that runs high at the doctor’s office—think of a doctor’s white coat—but normal outside of it. In fact, white coat hypertension can cause an older person’s reading to spike by as much as 30 to 40 points, Dr. Bisognano says.

“Some people think of coming to the doctor’s office like taking a standardized test or an evaluation,” he says. “They get anxious.”

That anxiety can lead to the release of stress hormones. Combine that with other stressors, like rushing in from the parking lot or worrying about something in your personal life, and you can be talking about a pretty substantial spike, Dr. Alexander says.

If your blood pressure is unexpectedly high at the beginning of your appointment, your doctor may retake it at the end of the visit to see if it leveled off. If it stays elevated throughout your visit, your doctor may suspect white coat hypertension and ask you to start checking your blood pressure at home to get a more accurate representation.

Important note: If your blood pressure measures fine at the doctor’s office but consistently runs high at home, that’s not something to shrug off. That describes a condition called “masked hypertension,” Dr. Bisognano explains. In this case, chronic home or work stress leads to an increase in blood pressure during your everyday hours, while the relative “calm” of the doctor’s office can cause it to drop.

“People with masked hypertension are actually at higher risk than those with white coat hypertension, since their blood pressure is high for 23 hours of the day,” he says.

Blood-Pressure Booster #6: You Crossed Your Legs

If you’re at a doctor’s office, the doctor or nurse taking your reading will probably instruct you not to sit this way, but if you’re taking it yourself at home, it can be easy to revert to this habit.

“Crossing your legs compresses an artery in your leg, so there is less blood flow,” Dr. Bisognano says. “When you compress the arteries, the pressure goes up.”

For an accurate reading, sit comfortably with your legs uncrossed and feet flat on the floor.

So, When Should You Worry?

If your doctor has given you any instructions for measuring your blood pressure at home, follow those exactly, including when you might need to call for an appointment or get emergency care.

In general, for people who haven’t yet been diagnosed with hypertension, blood pressure readings of 130/80 mmHg on more than two occasions would warrant an appointment with your doctor, Dr. Alexander says.

In some cases, one-off readings may mean you need to get medical care sooner. If your systolic pressure or top number is 180 mmHg or higher, or your diastolic pressure or bottom number is 100 mmHg or higher:

• But you are not experiencing any symptoms: Call your doctor for a same- or next-day visit.
• And you are experiencing symptoms like shortness of breath, chest pain, or numbness: Go to the emergency room.

And in the long term, while any of the factors above can elevate your blood pressure temporarily, you shouldn’t use them to explain away consistently high readings, Dr. Bisognano says. If your blood pressure is regularly coming back high, even after taking your readings accurately and avoiding behaviors that can spike it, you need to loop in your doctor. Controlling high blood pressure with lifestyle changes like diet and exercise, medication, or a combination of both is vital to reducing your risk of health complications.

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