What is white coat syndrome?
It’s blood pressure that reads higher at the GP than at home. On average, about 10 higher on the top number. But 27 studies linked untreated white coat hypertension to more heart and circulation problems.
On this page
What is white coat syndrome?
It’s when your blood pressure is higher at a clinic than at home. Blood Pressure UK says the stress of being in clinic raises it, and that it’s fairly common.
You may not even feel stressed. Most people are more tense than usual in medical settings and don’t realise it.
Think of it like stage fright. Your body reacts to the room, not to your normal day.
| Term | What it means | Who says |
|---|---|---|
| White coat syndrome (or white coat effect) | Higher in clinic than at home, whatever the numbers. | Blood Pressure UK |
| White coat hypertension | Over 140/90 in clinic, but lower than 140/90 at home. | Blood Pressure UK |
| White-coat effect | A gap of more than 20/10 between clinic and home or daytime 24-hour monitor averages, at diagnosis. | NICE |
| Masked hypertension | The reverse: under 140/90 in clinic, higher outside it. | NICE |
Sources: Blood Pressure UK; NICE NG136
Had a high reading at the GP? Ask about a home or 24-hour check before anything else.
How much higher is blood pressure at the doctor’s?
On average, the top number reads about 10 higher in clinic and the bottom number about 5 higher. If you feel very worried, it can be up to 30 higher.
To find your gap, take your home average away from your clinic reading. Do it for the top number.
- 10 mmHg or belowUp to the average gap of about 10.
- Above 10 up to 20 mmHgBigger than average. Within NICE’s line.
- Above 20 mmHgMore than 20. NICE calls this a white-coat effect when it’s found at diagnosis.
Sources: Blood Pressure UK; NICE NG136
The bottom number counts too. There, NICE’s line is a gap of more than 10.
Your gap doesn’t tell you if your blood pressure is high. Your home average does. The NHS high line at home is 135/85 or higher.
Home average 135/85 or more? That’s high even away from the clinic. Show your GP.
Is it white coat or real high blood pressure?
How your GP tells them apart
- 1
Repeat in the room
At 140/90 or more, a second reading, and a third if it’s very different. The lower of the last 2 counts.
- 2
24-hour monitor
Offered at 140/90 to 180/120. Home readings if it doesn’t suit you.
- 3
Average it
At least 14 daytime readings, or at least 4 days at home, ideally 7.
- 4
The answer
High blood pressure if the clinic reading is 140/90 or more and the average is 135/85 or more.
Sources: NICE NG136; NHS
A 24-hour monitor takes at least 2 readings an hour while you’re awake. You have it fitted at a GP surgery, health centre or hospital and return it the next day.
High in clinic but lower at home? That’s the pattern Blood Pressure UK calls white coat hypertension.
Not sure what your two numbers mean? See blood pressure readings explained.
How do I get a true blood pressure reading?
Six steps for a true home reading
- Wait 30 minutes after eating, smoking, caffeine drinks like coffee, or exercise, and go to the toilet first.
- Sit quietly for 5 minutes, back supported, feet flat, arm resting at heart height.
- Put the cuff about 2 cm above your elbow. Don’t talk, move or cross your legs.
- Take 2 readings at least 1 minute apart, morning and evening.
- Keep going for at least 4 days, ideally 7.
- Ignore day 1 and average all the rest.
Sources: Blood Pressure UK; NICE NG136
At the GP, arrive a few minutes early if you can and sit quietly first.
Already diagnosed with high blood pressure? If you have a white-coat effect, NICE says your GP can consider home or 24-hour checks as well as clinic ones. NICE sets the home and 24-hour lines 5 lower than the clinic line, so 135/85 at home matches 140/90 in clinic.
Never stop or change a prescribed medicine without your prescriber.
Picking a monitor and keeping a record: see how to measure blood pressure at home.
Is white coat hypertension dangerous?
A 2019 review pooled 27 studies.
Untreated white coat hypertension was linked to about a third more heart and circulation problems, and deaths from any cause, than normal blood pressure.
People already treated for high blood pressure with a white-coat effect showed no clear link.
Read it like a weather forecast. A higher chance of rain isn’t a promise of rain. These studies show a link, not a cause.
Blood Pressure UK says your blood pressure could creep up into high blood pressure. Your GP will suggest how often to have a check.
If your blood pressure is raised but not high enough to diagnose, NICE says you should get healthy living advice. Keep checking at home between visits.
If it does creep up, see stage 1 and stage 2 hypertension and high systolic blood pressure.
When to speak to a GP
High blood pressure does not usually cause symptoms. Speak to a GP if:
- A clinic or pharmacy reading was 140/90 or more, and you haven’t been offered a home or 24-hour check.
- Your home average is 135/85 or more.
- A clinic reading was 180/120 or more. NICE advises checks for organ damage as soon as possible. If you also have new confusion or chest pain, NICE advises a specialist check the same day.
- You’re 40 or over and haven’t had a check for more than 5 years. Many pharmacies check for free.
Often get headaches or blurred vision, or chest pain that comes and goes? Get help from NHS 111. Do the same for other symptoms you’re worried could be from high blood pressure.
Call 999 for sudden chest pain or discomfort that doesn’t go away, which can feel like squeezing, pressure, burning or indigestion. Call too for pain that spreads to your arm, neck, jaw, stomach or back. The same goes for chest pain with sweating, feeling sick, light-headed or short of breath.