Should You Discard the First Blood Pressure Reading? What the Evidence Says

Research explainer: the first-reading myth

Short answer: Do not automatically throw away the first valid home blood pressure reading just because the second is lower. Write down both planned readings, taken at least one minute apart, unless your clinician gave you a different protocol. A reading spoiled by talking, movement, a cuff error, or another known setup problem is different: label what went wrong, correct it, and restart. Also, “discard the first day” in some multi-day protocols is not the same as discarding the first reading of every pair.

Here is the kitchen-table version. Your first screen says 148/86. After a quiet minute, the second says 140/82. It is tempting to call the first number “nerves” and keep only the lower one. It is just as tempting to press start three more times until the display feels reassuring.

Neither habit creates a clean record. The useful question is not “Which number do I like?” It is “Which measurements were valid, and what does my assigned protocol say to do with them?”

First, separate the three different “firsts”

Much of the confusion comes from using one phrase for three situations. They need different answers.

First valid reading in a sessionThe first result after proper rest, posture, cuff placement, and a quiet measurement.
First day of a seriesDay one of a clinician-requested three-day, seven-day, or other home monitoring schedule.
First attempt with a known problemA run interrupted by talking, movement, a slipped cuff, an error code, or another clear technique failure.

A blanket rule such as “always discard the first” hides these distinctions. The American Heart Association’s current home-monitoring instructions say to take two readings one minute apart and record the results. They do not tell every home user to erase the first valid member of each pair.

The evidence is more interesting than the myth

First readings often run higher on average. That observation is real. The leap from “often higher” to “therefore wrong” is where the myth begins.

Within one sitting: A 2015 study examined three sequential readings across a community sample, general practices, and a hypertension center, totaling 2,929 people. Systolic pressure generally fell across repeated readings, but some participants had their highest result third. Including versus excluding the first reading produced similarly strong correlations with daytime ambulatory blood pressure. The authors did not support routinely discarding the first measurement and favored repeated measurement regardless of the first value. This was not a home-only study, which matters when applying it to a home routine. Read the study in the Journal of Human Hypertension.

Across several days: A 2022 analysis of 2,122 participants found that day-one home averages were about 2.8/1.4 mmHg higher than later days. In a three-day schedule, excluding day one changed hypertension classification for 120 participants, or 6%. With schedules longer than three days, the effect of excluding day one was negligible. That result supports a day-one rule in some short diagnostic schedules, not a universal rule to delete the first reading every morning and evening. Review the study abstract and DOI record.

Recognized guidance reflects that nuance. The American Heart Association scientific statement on blood pressure measurement says to average all readings for a monitoring period while noting that some protocols exclude the first day. The European Society of Hypertension position paper calls the need to discard day one a matter of debate and notes that its impact appears small when more monitoring days are available.

So the honest answer is protocol-dependent. A clean first reading contains information. A formal diagnostic schedule may still tell you to exclude day one when the final average is calculated. Your clinician should specify which rule applies.

A decision tree for the next time the numbers disagree

Keep, flag, or restart the first reading
Source note: This TrueVitals USA decision tree synthesizes the AHA’s five-minute preparation and two-reading guidance, its scientific statement on averaging a monitoring period, and the protocol distinctions in the ESH position paper. It is a recording aid, not an emergency decision rule.

How to record a higher first reading without cherry-picking

A transparent log keeps the original readings and the calculation separate. Average the top numbers together and the bottom numbers together. Do not average all four numbers into one.

Worked two-reading record card
Entry What happened Keep? What goes in the log
Reading 1 148/86 after a clean setup Yes 148/86, time, arm, and any requested context
Reading 2 140/82 after one quiet minute Yes 140/82, recorded as the second result in the pair
Pair average Systolic: (148 + 140) ÷ 2
Diastolic: (86 + 82) ÷ 2		 If the plan uses averages 144/84, while preserving both original readings
Known-bad attempt Talking, movement, cuff slip, or an error code Not as a valid reading “Invalid attempt,” the reason, and the new pair after setup is corrected
Source note: The values are an arithmetic example, not a treatment target or emergency threshold. The one-minute spacing follows the AHA guidance linked above. Use the averaging and exclusion rules supplied by your own clinician or monitoring program.
Caregiver script: “The first reading is 148 over 86. I wrote it down. We will stay quiet for the planned minute, take the second, and follow the written plan.” That is calmer and more useful than “That looks bad” or “Let’s keep trying until it drops.”

What changes the answer in real homes

Your monitor shows its own average

Find the exact manual before copying one displayed “average.” Devices differ. Some average a selected memory period, some average a fixed number of recent readings, and some run several measurements after one start. Confirm which readings, users, dates, and times are included. A household with two users can create a very tidy but meaningless average if profiles are mixed.

The first attempt produced an irregular-heartbeat symbol

Do not delete the reading simply because the next screen looks calmer. Record the result and the icon, correct any movement or talking, and follow the device instructions and your clinician’s plan. Our irregular-heartbeat symbol guide explains what a repeat can and cannot tell you.

The first and second readings are far apart

There is no safe homemade rule that says the lower reading automatically wins. Check for a known technique problem, preserve valid results, and use the repeat sequence your clinician or device manual specifies. If the difference keeps happening under controlled conditions, take the monitor and your log to the next appointment rather than inventing a personal correction factor. The guide to inconsistent home readings helps audit cuff fit, posture, timing, and rest.

Medication timing is part of the assignment

Some structured home protocols request morning readings before blood pressure medication. That is a measurement schedule, not permission to delay, skip, or change a dose. Follow the timing your prescriber gave you. If the instructions are unclear, ask the clinic to write down when to measure and when to take medication.

You are helping a parent who becomes anxious

Agree on the number of readings before the cuff starts. Keep your voice neutral and do not announce a verdict after each screen. Our caregiver measurement guide covers consent, positioning help, and a clean handoff to the care team.

Why “discard day one” belongs on a separate line

A clinic may ask for two morning and two evening readings over several days, then calculate an average. Some protocols use every valid reading. Others exclude the first day because day-one readings can be higher and less stable. The American Family Physician review of home measurement describes three to seven days of readings and notes that some guidelines omit day one.

Write the rule at the top of the log before starting: “average all valid readings” or “exclude day one from the final average.” Do not decide after seeing the numbers. If day one is excluded from the calculation, keep the raw readings available for the clinician. Excluded from one average does not mean erased from history.

For a shareable record, the TrueVitals BP Log is free for TrueVitals customers. A paper sheet works too. The important part is preserving date, time, both readings, and notes about anything that made the session unusual. Our guide to doctor-ready home readings explains why that context matters.

Four myths worth retiring

Myth: The first reading is always wrong.
Evidence: First readings are often higher across groups, but not for every person or every session. A valid first measurement still carries information.
Myth: The lowest reading is the most accurate.
Evidence: A preferred-looking result is not a validation method. Accuracy depends on the device, cuff fit, technique, and the planned measurement sequence.
Myth: The first reading and the first day are the same rule.
Evidence: One concerns measurements within a sitting. The other concerns how a multi-day average is calculated.
Myth: More repeats always make the answer better.
Evidence: Repeating until a preferred number appears changes the protocol and invites selection. Take the planned readings, record them honestly, and stop unless your instructions say otherwise.

Frequently asked questions

Should I throw away my first blood pressure reading?

Not automatically. If it was taken with a clean setup, record it and take the planned second reading at least one minute later. Exclude a reading or day only under the protocol your clinician gave you.

Which blood pressure reading should I write down, the first or second?

Write down both valid planned readings. Do not keep only the lower number. If an attempt was spoiled by a clear error, label the reason and restart rather than hiding what happened.

Should I average two home blood pressure readings?

Many structured home-monitoring plans use an average of valid readings, but follow the calculation your clinician requested. Average systolic numbers together and diastolic numbers together while preserving the originals.

Why is my first blood pressure reading often higher?

Blood pressure can settle during quiet repeated measurement, and the first reading may follow less rest or more alertness. It is often higher across groups, but that pattern does not prove every first reading is wrong.

What if the first reading worries me?

Use the symptom and result instructions from your health care team. Do not delay urgent help by repeating measurements indefinitely, and do not change medication based on a blog article or one home result.

References

  1. American Heart Association. Home Blood Pressure Monitoring. Last reviewed August 14, 2025.
  2. Muntner P, Shimbo D, Carey RM, et al. Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association. Hypertension. 2019;73:e35-e66. doi:10.1161/HYP.0000000000000087.
  3. Parati G, Stergiou GS, Bilo G, et al. Home blood pressure monitoring: methodology, clinical relevance and practical application. Journal of Hypertension. 2021;39:1742-1767. doi:10.1097/HJH.0000000000002922.
  4. Salazar MR, Espeche WG, Aizpurúa M, et al. Should the first blood pressure reading be discarded? Journal of Human Hypertension. 2015;29:373-378. doi:10.1038/jhh.2014.98.
  5. Kyriakoulis KG, Ntineri A, Niiranen TJ, et al. Home blood pressure monitoring schedule: optimal and minimum based on 2122 individual participants’ data. Journal of Hypertension. 2022;40(7):1380-1387. doi:10.1097/HJH.0000000000003157.
  6. Weinfeld JM, Hart KM, Vargas JD. Home Blood Pressure Monitoring. American Family Physician. 2021;104(3):237-243.

Educational note: This article explains measurement and recording methods. It does not diagnose high or low blood pressure and does not replace the plan from your health care professional. Do not start, stop, delay, or change medication because of one home reading or this article.

Make the routine easier to repeat

A useful home record starts with a validated monitor, a cuff that fits, and a routine simple enough to follow the same way tomorrow. When you are ready to compare designs and fit ranges, view the TrueVitals Pro 365 upper-arm monitor.