White Coat Hypertension

White coat hypertension is when blood pressure at the clinic is 140/90 mmHg or higher, while the average at home is below 135/85 mmHg and the 24-hour average is below 130/80 mmHg. The term refers to the white coats worn by health workers, because the rise is triggered by the setting of the examination. This condition is fairly common, especially in older adults, women, and people who do not smoke.

Why It Happens

During an examination, the body can react as if it were facing a stressful situation. The nervous system releases hormones that speed up the heart rate and narrow the blood vessels, so blood pressure rises temporarily. This reaction often goes unnoticed; many people feel calm, but their readings are still high when measured by a health worker. After leaving the clinic, blood pressure returns to its usual level. Small things before the examination can also raise the reading, for example arriving in a rush, having just had coffee or a cigarette, holding in urine, or talking while the cuff inflates. That is why measuring correctly is an important part of telling a temporary rise apart from true hypertension.

White Coat Effect in People on Treatment

In people with hypertension who already take medicine, a similar rise is called the white coat effect. Clinic readings appear not to have reached the target, even though blood pressure at home is already controlled. Without measurements outside the clinic, the medicine dose may be raised beyond what is needed, causing dizziness or weakness when standing, especially in older adults. The opposite, normal blood pressure at the clinic but high blood pressure outside it, is covered on the Masked Hypertension page.

Is It Dangerous?

White coat hypertension still carries risk, although less than sustained hypertension. Compared with people who have normal blood pressure, people with this condition are more likely to develop sustained hypertension and slightly more often have thickening of the heart muscle. A pooled analysis of studies found an increased risk of heart and blood vessel events in untreated white coat hypertension. For this reason, guidelines recommend lifestyle changes and regular blood pressure monitoring outside the clinic, while medicine is considered in certain situations. An overview of hypertension is covered on the Hypertension page.

White coat hypertension can only be confirmed by comparing readings at the clinic and outside the clinic. If clinic blood pressure is 140/90 mmHg or higher, guidelines recommend confirming it with home measurements over 7 days or 24-hour monitoring, especially in grade 1 hypertension and in older adults.

The diagnosis is made if readings outside the clinic are normal: a home average below 135/85 mmHg and a 24-hour average below 130/80 mmHg. The doctor also checks an ECG, a urine test, blood sugar, and cholesterol to assess your overall risk. Because some people with this condition later develop sustained hypertension, measurements outside the clinic should be repeated regularly, for example once a year or as your doctor advises.

High readings at the clinic still need follow-up and should not be ignored. Make an appointment if:

• Your blood pressure is 140/90 mmHg or higher at the clinic but normal when measured at home
• You are already on treatment and clinic readings are always high, but home readings are often low or you easily feel dizzy when standing
• Your average home blood pressure starts to reach 135/85 mmHg or higher during regular monitoring
• You have diabetes, kidney disease, or a family history of heart disease

Go to the emergency room right away if you develop chest pain, severe shortness of breath, weakness on one side of the body, slurred speech, or fainting.