Accurate home blood pressure monitoring comes down to three things: an upper-arm monitor with a cuff that fits your parent's arm, five minutes of quiet rest before pressing start, and measuring at the same times every day. Under the guidelines of the Thai Hypertension Society, measure for 7 consecutive days before a doctor's appointment, twice a day (morning and before bed), with at least two readings each time. A home average of 135/85 mmHg or higher is in the high blood pressure range, and the record should go to the doctor for review. Increasing, reducing or stopping medicine is always the doctor's decision.
Many families know this scene. Mum's morning readings at home look fine, but at the appointment the nurse measures her outside the consulting room and the number is high enough for the doctor to ask whether she has been taking all her medicine. She insists she has, and the son who brought her cannot add anything, because the home readings are on a scrap of paper left at home, or were never written down. Another family has the opposite problem: Dad is always normal at the hospital but high at home, and nobody knows. Both are solved the same way: measure correctly at home and keep an organised record. This guide covers choosing a monitor, posture, fitting the cuff, the 7-day schedule, a sample log, and the numbers and symptoms that mean telling the doctor or calling 1669.
Quick answer
- Use a validated upper-arm monitor with a cuff that matches your parent's arm; wrist or finger monitors only when necessary
- Before measuring, rest for 5 minutes: back supported, feet flat, legs uncrossed, arm on a table with the cuff at heart level, no talking, and no tea, coffee or smoking for 30 minutes beforehand
- Before an appointment, measure for 7 consecutive days: in the morning within 1 hour of waking (after the toilet, before medicine and breakfast) and before bed, at least 2 readings each time, about 1 minute apart
- A home average of 135/85 or higher is in the high blood pressure range; take the record to the doctor and never adjust medicine yourself
- High at hospital but normal at home, or the reverse, both genuinely happen; the home record is the evidence the doctor needs
- For severe chest pain, weakness on one side, slurred speech, severe breathlessness or drowsiness, call 1669 immediately without re-measuring
1. Why measure at home when the hospital measures anyway?
A single hospital reading shows your parent's blood pressure in that one minute. Dozens of home readings show the doctor what it is like in real life.
On appointment day your parent wakes early, sits in traffic, walks from the car park, waits in a queue and worries about results, and all of it affects the number. At home they are in their normal routine. A full 7 days, twice a day, two readings each time gives the doctor at least 28 readings, which helps the doctor:
- Tell whether blood pressure is truly high, or high only at the hospital
- See whether current medicine controls it throughout the day
- Check whether it is dropping so low that your parent feels dizzy or faint
- Follow the trend over several weeks: better, the same, or worse
The family's job is to collect reliable numbers and get every one to the doctor. Interpreting them and deciding on medicine belong to the doctor.
2. Which blood pressure monitor to buy: use criteria, not brands
The right home monitor is an automatic upper-arm device with evidence of validated accuracy and a cuff that fits your parent's arm. Any make will do if it meets these criteria.
Upper-arm versus wrist monitors
The Thai Hypertension Society recommends a validated upper-arm monitor and advises avoiding wrist or finger devices unless necessary. Wrist monitors are convenient, but readings shift with wrist position; holding the wrist slightly above or below the heart changes the result. Older adults with a tremor, or who forget the correct position, often get unreliable numbers. If your parent cannot use an upper-arm cuff, ask the doctor what to use instead.
Checklist before you buy
- Automatic upper-arm measurement: one button, and the device inflates and reads by itself
- Evidence of validated accuracy: check the manual or box for testing against a medical standard; if unsure, ask a pharmacist or medical supply shop
- A cuff that fits: the usable arm range is printed on the cuff. Measure around the middle of your parent's upper arm with a tape measure; if it falls outside the range, find another cuff size for that model. A cuff that is too small tends to read high, and one that is too large may read low
- Large display readable without glasses
- Memory with separate users, so readings do not get mixed up when several people share one device
To check whether the home monitor is still accurate, bring it to the next appointment and ask the nurse to compare it with the hospital device on the same arm.
3. How to measure blood pressure at home accurately, step by step
Accuracy means doing it the same way every time: same position, same arm, same time of day, and a body that has settled. Then a whole week of numbers can be compared.
For 30 minutes beforehand, no tea, coffee or smoking. Let your parent use the toilet first, and if they have just been walking around or doing housework, let them recover before the rest period starts.
- Sit in a chair with a backrest, back fully supported; not on a bed or a soft sofa.
- Both feet flat on the floor, legs uncrossed.
- Rest the measuring arm on a table, palm up, with the cuff at heart level; raise the arm on a cushion if the table is low.
- Wrap the cuff on bare skin, not over thick clothing, and do not roll a sleeve up so tightly that it squeezes the arm.
- Place the lower edge slightly above the elbow crease, with the tube positioned by the marker on the cuff. Snug, not painfully tight, and not loose enough to slide.
- Sit quietly for 5 minutes, without scrolling a phone or watching stressful news.
- Press start. While the cuff inflates, your parent sits still, does not talk and does not move the arm.
- Write down the top number, bottom number and pulse straight away.
- Wait about 1 minute, repeat the same way, and record the second reading separately.
Tip: use the same arm every time and ask the doctor at the next visit which arm to use. If one arm must not be used for blood pressure, for example because of a dialysis access, follow the doctor's or nurse's instructions strictly.
If your parent cannot sit up with back support, or spends most of the day in bed, ask the doctor or nurse which position to use, keep to it every time and note it in the record, because readings in different positions cannot be compared.
4. Measuring blood pressure at home for 7 days: the schedule doctors want
For the 7 days before the appointment, measure every day, twice a day (morning and before bed), with at least 2 readings about 1 minute apart. If the doctor needs results quickly, the Society's guideline says at least 3 days is acceptable.
- Morning: within 1 hour of waking, after the toilet, before medicine and breakfast. The doctor wants blood pressure before the new day's medicine takes effect, which shows whether treatment covers the whole day
- Before bed: after the evening routine, with the same position and arm as the morning
- After 7 days you will have at least 28 readings. Bring them all, discard none, and do not skip weekends
If a session is missed, write "not measured" with a short reason rather than leaving a blank, so the doctor knows why data is missing. Outside the week before an appointment, measure as often as the doctor advises. Measuring whenever your parent feels anxious does not improve the data and usually makes them more stressed about the numbers.
5. Keeping a blood pressure log the doctor can use at a glance
A good record has the date, time, every reading, pulse, the arm used and a short note. Record every value honestly, not just the good-looking ones.
Sample log for one day
Write it as a list like this in a small notebook or a phone note.
- Monday morning, 06:40, seated in a chair, left arm
- Reading 1: top ..... bottom ..... pulse .....
- Reading 2: top ..... bottom ..... pulse .....
- Note: morning medicine not yet taken; up twice to the toilet last night
- Monday before bed, 21:30, seated in a chair, left arm
- Reading 1: top ..... bottom ..... pulse .....
- Reading 2: top ..... bottom ..... pulse .....
- Note: dizzy standing up from a chair this afternoon; settled after sitting down
In the note, record that day's symptoms, such as headache, dizziness, light-headedness on standing or palpitations, plus missed medicine, a new medicine, poor sleep, or an irregular-heartbeat symbol on the monitor. Even with a memory function, copy the readings into the notebook, because scrolling back through a device one value at a time is awkward in a consulting room.
Before the appointment, prepare a one-page summary
On the first page, note the dates covered, the arm and position used, any unusual symptoms that week and your questions for the doctor. Bring it with a list of every medicine your parent takes. If your home has no clear medicine system yet, see setting up a medication system for older adults at home.
6. Why is blood pressure normal at home but high at the hospital?
Blood pressure that is high only in a clinical setting is called white-coat hypertension: 140/90 or higher at a healthcare facility, but normal elsewhere. The reverse is masked hypertension: normal at the facility but high at home. Either way, the doctor needs the home record to decide.
High only at the hospital
Nervousness, travel and waiting can push the reading outside the consulting room above everyday levels without your parent noticing. What families should not conclude on their own is "their real blood pressure is normal, so they can stop their medicine". The doctor needs the full picture first, and some people still need follow-up even when home readings are normal.
Masked hypertension: high at home, normal at the hospital
This is more worrying than it sounds: the hospital numbers always look fine, so the doctor has no reason to suspect anything. The only way to find out is a correctly measured home record. If home readings are regularly high, take the record to the next appointment rather than waiting for symptoms.
Before deciding which pattern it is, make sure the home monitor is accurate, the technique follows section 3 and the schedule is complete. Whatever the result, never stop or reduce medicine because home readings are normal, and never add medicine because they are high.
7. What numbers to tell the doctor, and which symptoms mean calling 1669
The number to take to the doctor is a home average of 135/85 or higher (top number 135 or higher and/or bottom number 85 or higher). What calls for 1669 immediately is symptoms, not a number on the screen.
Take the record to the doctor for review
- A weekly average of 135/85 or higher in a parent never diagnosed with high blood pressure
- A parent already on medicine whose home readings stay above or below the target the doctor set
- A clear, regular difference between morning and bedtime readings
Call your parent's doctor or hospital without waiting for the appointment
- Frequent dizziness, light-headedness or near-falls when standing up
- Readings clearly higher or lower than usual for several days in a row
- New symptoms after starting or changing a medicine
- Readings beyond the alert numbers the doctor has set for your parent
Ask the doctor to set personal "alert numbers" for your parent: how high, how low, and whom to call. Write them on the first page of the logbook so everyone at home, including any caregiver, works to the same criteria.
Call 1669 immediately, whatever the monitor says
- Sudden, severe chest pain
- Weakness on one side of the body, slurred speech, or seizures that do not stop
- Rapid breathing, severe breathlessness, noisy or obstructed breathing
- Drowsiness, sweating and cold skin, or loss of consciousness
With these symptoms, do not waste time re-measuring to see whether the number comes down, and never give extra blood pressure medicine yourself. Call 1669 first. To prepare your home and know what to tell the dispatcher, read our emergency plan for older adults at home and calling 1669. If the doctor also wants fingertip oxygen readings, use the same notebook; see our guide to reading a pulse oximeter for older adults.
Mistakes families often make
- Measuring the moment your parent sits down. Readings tend to be high. Rest a full 5 minutes every time, timed rather than guessed.
- Measuring repeatedly and writing down only the lowest number. The doctor sees an unrealistically good picture. Take 2 readings as the guideline says and record both.
- Adjusting medicine by the numbers, such as stopping because home readings are normal or taking extra because this morning was high. This risks both surges and drops that cause falls. Write it down and call the doctor.
- One cuff for everyone. Dad has large arms, Mum slim ones, so someone's readings will be off. Measure each person's arm and use the matching cuff.
- A scrap of paper forgotten on appointment day. Use one notebook, or photograph the page on your phone every day.
When to bring in a professional team
Families can measure blood pressure themselves, but a morning-and-bedtime routine every day often clashes with working hours. If nobody is with your parent in the morning before medicine, they cannot put on the cuff because of a tremor or arm weakness, or they have several conditions and many medicines, a helper makes the numbers that reach the doctor complete and more reliable.
- Caregiver (nursing assistant): measuring vital signs and keeping records is part of a caregiver's daily routine, alongside meals and medicine on time. The family sets measurement times and alert numbers according to the doctor's instructions. A 12-hour shift is 1,800 baht per day (3-day minimum) or 30,000 baht per month; a live-in 24-hour caregiver is 2,500 baht per day or 36,000 baht per month. If unsure, try a short period before committing long-term, such as a week at 12,000 baht (12-hour shift) or 16,000 baht (24-hour live-in). See elderly care at home.
- Registered nurse: for parents with complex needs or several conditions who need an overall assessment. 3,500 baht per 12-hour shift, or a nurse home visit at 1,800 baht per visit. See home nursing.
- Escort to appointments: a caregiver picks your parent up at home, stays throughout and brings them back, so the logbook reaches the doctor complete. 1,800 baht for 8 hours, 200 baht per extra hour, transport charged separately. See hospital escort.
Frequently asked questions
Why is my parent's blood pressure normal at home but high at the hospital?
Usually white-coat hypertension: 140/90 or higher at a healthcare facility but normal elsewhere. Nervousness, travel and waiting all affect the number. Take a correctly measured home record to the doctor, and do not stop medicine on your own.
When should blood pressure be measured at home, and how many times a day?
Before an appointment, twice a day: in the morning within 1 hour of waking (after the toilet, before medicine and breakfast) and before bed, with at least 2 readings about 1 minute apart. At other times, follow the frequency the doctor advises.
How do I do 7-day home blood pressure monitoring?
Measure for 7 consecutive days before the appointment, record every reading with the date, time and pulse, and bring the whole record without discarding high readings. If the doctor needs results quickly, at least 3 days is acceptable.
What home blood pressure reading counts as high?
According to the Thai Hypertension Society, a home average of 135/85 mmHg or higher is in the high blood pressure range. It applies to an average over several days, not a single reading, and the diagnosis is made by a doctor.
Which is better, a wrist or an upper-arm blood pressure monitor?
An upper-arm monitor is better for home use. The Society recommends a validated upper-arm device and advises avoiding wrist or finger monitors unless necessary. Choose one with evidence of validated accuracy and a cuff that fits.
Blood pressure is high but there are no symptoms. Should we go to hospital now?
With no unusual symptoms, rest 5 minutes, measure again correctly and write it down. If it is still above the doctor's alert number, or much higher than usual, call your parent's doctor or hospital, and do not give extra medicine. With chest pain, one-sided weakness, slurred speech, severe breathlessness or drowsiness, call 1669 immediately.
Can I hire someone to measure and record my parent's blood pressure every day?
Yes. Measuring vital signs and keeping records is a routine daily task for KIN HomeCare caregivers: 1,800 baht per day for a 12-hour shift with a 3-day minimum, or 12,000 baht for a week if you want to try a short period before committing long-term. For parents with several conditions who need clinical assessment, a registered nurse is available.
Talk to the KIN HomeCare team
If you want your parent's blood pressure checks to run smoothly but nobody is home in the morning or at bedtime, tell the team about your parent's routine and your family's schedule. We will help you decide which caregiver shift to start with, or whether a nurse should visit first.
- Call 061-881-9399 (+66 61 881 9399) for elderly care, nursing and hospital escort
- LINE @KINHOMECARE
- Free consultation: the team helps you work out which service fits before you decide
- Home care available nationwide
This information is general guidance for families and does not replace advice from your parent's doctor.
Prepared by the KIN HomeCare team · Prices as of September 2026; please confirm with our staff before booking.
