6 Factors That Can Affect Your Blood Pressure Reading

Is your blood pressure within the healthy range? Experts recommend that your top number, or systolic blood pressure, be under 120, while the bottom number (diastolic blood pressure) be under 80.

High blood pressure (hypertension) is a cause for concern, since it puts you at an increased risk for heart disease. Nonetheless, it is possible for a blood pressure reading to be inaccurate. Here are six reasons--some of them unexpected--that may explain a high blood pressure reading.

Factors That Affect Blood Pressure Readings

  1. Stress and anxiety. A stressful situation can cause a dramatic, temporary spike in your blood pressure. A single incident is not cause for alarm; however, if this happens frequently, it can damage your blood vessels, heart, and kidneys. Stress can also cause you to engage in behavior that may further damage your heart, such as smoking or drinking.
  2. The season. Blood pressure tends to be higher in the winter because low temperatures cause your blood vessels to narrow; this means you need more force to push the blood through your body.
  3. Alcohol. Drinking three or more drinks at once may cause a temporary uptick in blood pressure. Over time, excessive drinking may cause a long-term increase.
  4. Daily patterns. Your blood pressure is usually lower while you sleep and shortly after waking, then rises throughout the day, peaking in mid-afternoon.
  5. Caffeine. Coffee and other caffeinated beverages can also cause a brief but dramatic increase in blood pressure.
  6. Measurement errors. Your blood pressure measuring device may not be working properly, or you (or your healthcare provider) may not take your blood pressure correctly. Even something as innocuous as a tight belt can affect your reading.

Dealing With a High Blood Pressure Reading

If you get a high blood pressure reading, try again later. Take a walk or practice slow, deep breathing so you're calm before you try again. Drinking water and even avoiding certain foods, such as dark chocolate, garlic, and bananas beforehand may help ensure an accurate reading.

If you continue to get high readings and you've ruled out outside factors as possible culprits, then see your physician. You can make simple lifestyle changes to lower your blood pressure, or if appropriate, seek medical care.


Sheldon G. Sheps, M.D. "High Blood Pressure." Mayo Clinic. August 26, 2011. http://www.mayoclinic.com/health/white-coat-hypertension/AN02014

Mayo Clinic. "High blood pressure." Web. http://www.mayoclinic.com/health/blood-pressure/AN01786

Ray, Claiborne. "Pressure Problems." New York Times. Web. 13 December 2010.