Brief Answer:
Ideally it is 120/80; but upto 140/90 is acceptable.

Detailed Answer:

Hi,

There is a range of blood pressure lemit for normal people. For a healthy person as you mentioned, blood presure of less then 140 systolic and less then 90 dystolic that is less then 140/90 is upper acceptable readings. This is where we don't treat and accept it as upper normal though the ideal one is 120/80.
If more then 140/ 90 we generally advise to treat it. Initially with life style (like excercise and salt restriction) but if still high then we may need to start medical treatment.
However few things should be kept in mind regarding blood pressure.

1. BP should not be decided by single readings as some times readings may be normally high for a moment (except if it is very high like if more then 180 /110).

2. If readings are between 140 and 160 we should repeats it many time for about two weaks at home to find an average or in hospital for 24 hours with a special machine to be sure about the true value of BP.

3. To be very honest benefit is always there if we reuce the BP( for same reasons the Americans now even treat if more then 135/85; but British guidlines are for over 140/90) however we weigh the benefits of reducing it against the risk of drugs and costs of drugs. So the benefit of treatment is maximum only once it's over 140/90.

4.BP if high mostly does not cause harm immediately so we dont need to panic (until BP is very high like over 200 by 110).

The lower lemit is not an issue..We are not mostly concerned about the lower lemit of the BP outside hospital. Untill pt is very sick for some reosons and is in shoak which is a different story. However if a person feels fainting, dizzy, or black out we want to chek his BP to be above 80 /60 atleast. That's mostly for some diseases which could be corrected.

Hope I have answered your question. Please feel free to ask anything else in this regard.
Regards,
Dr. Rahman

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