Pernicious Anaemia Society
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Does sudden high blood pressure matter and is it B12d or medication related?

Hi everyone - hope you are looking forward to Easter

I'm just back from GP - not my usual one. I usually have lowish blood pressure - have never seen it higher than 125 or 85. Had to go to hospital on holiday recently to get B12 and they found it to be 144 over 90 which alarmed me a little. I've been feeling ill - dizzy, ears ringing and hot inside, head throbbing - and took my BP a couple of times in the last few days. It has ranged from 149/99 (back from a job interview yesterday and had to go straight to bed at 5pm as felt ill) to 137/93 (lying in bed this am after a good night's sleep and breakfast in bed).

For me these levels seem exceptional and a sudden change. GP has just said they aren't worried about a level of 140+ / 90+.

I'm usually 110/70 and think of 125/ 80 as high - to be 149/99 as I was yesterday seems astronomical. GP agreed to more blood tests (K, Ca, Folate, Mg) but left it at that, and I won't have results for 3 weeks.

Does anyone have experience of a change in BP of this sort after a few months SI? I do one jab a week of Hydroxy and am also taking folate.

4 Replies

Hi Masie44. As far as I am aware, injecting B12 IM or SC does not cause high blood pressure (hypertension). In rare cases, B12 injected IV (directly into the vein) can potentially cause high blood pressure - but only when this is a pre-existing condition (and at a level much higher tan yours is).

Blood pressure does fluctuate quite widely during the day and what you describe is not unusual. When the heart has to work harder (for instance when doing exercise or under stress) blood pressure automatically increases as the heart work harder to cope with the extra demands put on it.

I hate going to the surgery - mighty amounts of stress - so when the nurse takes my blood pressure it usually hits 140/90 - normal for me is 110/80 - quote low. After I've been there ten minutes, she takes it again and it's magically back to somewhere near my 'normal'. And if I've been dodging about doing activity (and how I wish I could do that more often 😄), it again goes up. When I had to test my own BP four times a day, the fluctuation was quite marked - along the lines you describe above.

Also - BP does tend to raise slightly with age, so your 'normal' may increase slightly over the years.

However, if BP raises above 145/95 and is consistantly at that level, then your GP may want to keep an eye on it...or maybe ask,you to monitor it and keep a record at home. (The key here is a consistantly high level rather than a level that swings up and down). this one I'd trust your GP - and how refreshing to be able to say that here 😄. always...if your remain worried or have any further concerns, pop along and discuss it again with your GP.


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thank you for the reassurance!


Hi Mashie44

I guess a job interview would qualify as a good reason for an increase in your blood pressure and even so 144/99 is only just over the borderline into being "high".

I'm not medically trained but as I do get a slight momentary palpitation after a B12 injection as far as I know they haven't led to an increase in my BP after 45 years.

I hope things settle down for you soon.


I would look into magnesium. It can reduce blood pressure. WebMD. Easy way to check, if you dont want to take a pill, is to take an epsom salt bath. Not hot water, just warm. Minimum of 20 minutes, 30 minutes is better. Dead sea salts have higher levels of multiple minerals and your body isnt going to absorb so much that you have any adverse reaction, such as is possible with a pill.

Take a bath, check your blood pressure. Hope this helps.

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