Pernicious Anaemia Society

I'm new here - Tight chest/chest pain/pressure when starting B12 injections

Hi all,

Im not sure that my chestpain is from B12 injections, but its a possibility, and i would like to ask you all, if any of you has gotten tight chest feeling or pain in the chest from injecting B12 ? I have both injected hydroxo and methyl alternating. Im injecting in the morning, but i dont get this tight chest feeling until the evening. Im taking potassium supplements. Any ideas ?



10 Replies

Hi MangoDenmark.

Sudden onset of tightness and pain in the chest should always be treated as a medical emergency.

I see your are taking potassium supplements. These should only ever be taken under medical supervision, and potassium levels in the blood checked regularly by your GP. Low or high potassium levels can have an effect on the way the heart functions.

If I was you I'd want to get this checked out immediately so I suggest you go along to a walk-in-centre or to A & E (preferably A &E) who will be able to do appropriate tests and hopefully send you away reassured.

Take our potassium supplements with you and be sure to let them know what you have been taking.

If it turns out to be B12 related you've lost nothing but a bit of time and at least you'll know what it is in the future.

Hope all goes well.


Hi Foggyme :)

Thanks for your concern - i did follow your advice and called a doctor. When i mentioned chest pains they dispatched an ambulance and i got a full heart checkup at the ER. Everything was fine. I live in Denmark.

Yes i do get reg. bloodwork, but my doctor is sort of a moron. I know that potassium is not something to fool around with, but im having a hard time eating anything due to swallowing difficulties, and after some investigation i found out that swallowing disorders is common in B12 deficiency - and i also read that when one starts B12 and folate treatment, the potassium can get low.

Is there any real risk associated with taking potassium if i'm 100% sure that I including meals does not get anymore than 3 grams a day ? Im not getting any other food than a meal in the evening (200 grams fish and a salad of mango and avocado). This meal i have calculated gives me approx. 1 gram of potassium and i have therefore supplemented with 2 grams of potassium. 3 grams in a day is till under the reccomended intake i believe ?

Im still very curious if anybody else have had chest pressure/pains when supplementing B12 ? I have taken 1mg of hydroxo/methylcobalamin every second day for 14 days.

Im also very int. in hearing if others have had swallowing difficulties due to B12 depletion ? Actually my cobalamin is within range(lower Quadrant), but my MCV and MCH is both elevated, over top reference, and my ferritin is very low(30). As low ferritin should lower the values of MCV and MCH, but they are in fact pretty elevated, combined with a lot of neurological symptoms, has lead me to believe, that im B12/folate depleted. But i dont know!

My symptoms has been difficulty swallowing, PVC's, Pins and needles, depression, anxiety.

After i started giving myself injections with B12, my pins and needles has subsided tremendously.

Again thanks for your concern - im glad i did follow your advice.



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Hi MangoDenmark. I'm really pleased that you went to the ER and had your tight chest / chest pains checked out. And phew, all okay, thank goodness.

So first, the MCV and MCH - high levels of both mean you have larger than average red blood cells: you have macrocytic anaemia. The most common cause of macrocytic anaemia is pernicious anaemia (though they can also be caused by certain medications, bone marrow dysplasia, alcoholism and non-alcoholic liver disease).

So, most likely have B12 deficiency and this often goes hand in hand with low folate.

And yes, your ferritin level of 30 is low (it should be 80 -100) and, incidentally, low ferritin can cause some of your symptoms, including the difficulty in swallowing.

With respect to the potassium supplements, I have to say that I would never advise anybody to take these unless under direct medical supervision. For instance, it's is dangerous for people with kidney disease, heart disease, diabetes, Addison's disease, stomach ulcers, or other health problems to take these as a supplement.

It's looking like you do have a health condition (most likely pernicious anaemia - but you should have blood tests to rule,out other potential causes I.e. Liver function tests etc). Low ferritin can also be caused by stomach ulcers (which can't at this stage be ruled out) so, you certainly 'fit' the 'under medical supervision' criteria for potassium supplements. In addition, it's not really possible to rule out whether anything else is going on in your body, health wise? Only a medic can assess this properly.

The issue of daily recommended doses for potassium does not adequately account for the above factors so I really would advice great caution where potassium is concerned. Again, I would say don't take it unless under medical supervision.

You are right about potassium potentially being lowered when injecting large doses of B12 (usually at the loading dose stage) but this is usually managed by a medic who will check your levels via blood tests. Only sure safe way to do it, I'm afraid 😀.

One of our other administrators here on the forum ( fbirder ) is a chemist, and much more knowledgable about these issues, so perhaps if he sees this thread he'll leave a comment as well 😀.

Which bring me back to the possibility of PA. I'm really surprised that your medic seems to have ignored your high MCV and MCH and low ferritin. Even though your cobalamin was in range, I should imagine it was very low in the range and as you are symptomatic of B12 deficiency, your medic should be treating you for B12 deficiency. And your macrocytic anaemia (demonstrated by the high MCV and MCH) should be red flags that prompt him to also test you for pernicious anaemia (anti-IF antibodies blood test).

Also - if you have one autoimmune condition (which is what PA is) it's likely that you may have another (i.e. Hashimoto's thyroiditis).

Whilst it looks fairly certain that you do have B12 deficiency and PA, one of the problems is that there are a lot of cross-over symptoms between B12 deficiency and other medical conditions so I think that to self treat with B12 injections at this stage might risk other conditions being missed and left untreated if medical advice and proper investigation is not undertaken.

My advice would be to read the PAS pinned posts (to the right of this page when you log on) so that you can approach your doctor from an informed position and ask him to investigate your symptoms further and test you for PA and thyroid conditions (as a minimum).

Sorry I can't give you any easy answers and if you have any further questions or need further support, please post again. Lots of knowledgable folk here who will pop along to help.

Again, pleased all went well at the hospital.

Take care and let us know how it goes 😀.

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Hi foggyme,

Its late in Denmark, i will answer shortly

I have started a new thread describing all my symptoms.

I have had complete body check up, including liver, kindeys heart everything.

My ferritin is 30 yes but is is mcg/L, another scale that you use, but the reference here in denmark for ferritin is 20 - 300 mcg/L, so it is borderline low.

Pls. take a look at my other thread.

Sleep well.

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Hi Mango Denmark. Borderline low is not good enough for someone with B12 deficiency. Your level needs to be in the top third of the reference range, whatever reference range is being used, so 30mcg/L in the reference range 20 - 300mcg/L is far too low.



Hi Foggyme,

Im confused. Its my ferritin level that is borderline low.

Not the folate. I dont know my folate levels, but in a grou at facebook, the advice, that if you have neurological symptoms, you should take 1 injektion B12 every other day, and 5 mg folate eveery day.

Do you agree ?


Hi MargoDenmark. Sorry, mistype...was talking about ferritin. 30 is very low and will make you feel very you need to raise levels of ferritin. Thanks - post edited.

Yes about the B12...until no further improvement...but ought to be under doctors direction and with a referral to a neurologist because of neuro symptoms (need to be sure that something else is not going on as symptoms of B12 deficiency can also be symptoms of other neurological disorders).

Folate - 5mg a day is usually given to those who have known low folate levels. Not everybody needs that much and probably not if injecting less often than every other day. (400ug of folate daily is sufficient if you do not have low levels of folate). Too much folate can have side effects (I.e. Insomnia - more information on the Internet).

But....certainly need folate if levels are low. Best to get levels checked by medic. Folate should be started 24 hours after the first B12 injection, and not before. If folate proves to be low, then folate supplementation should not take place unless low or deficient B12 is first addressed due to risk of neurological damage.

Hope this helps 😀

P.s. If you have never injected the type of cobalamin you intend to use, then the first injection is best done under medical supervision because of the (albeit rare) possibility of a reaction - anaphylactic shock - which requires immediate and urgent medical intervention 😖


Yes it deffinately happens.

Tight chest feelings with B12. It started happening to me after about 6 loading doses then 1 weekly injection.

I started getting chest tightness/pain and heart palpitations so I layed off injections for a while. I found that if I had more than 1 injection a week it started again.

I experimented and found it was deffinately the B12 injections.

Now I have 1 injection a week sometimes 1 in 2 weeks and it doesn't happen.

I think it happens to some people when they get too much or more accurately have the injections too frequently.

It does happen !

Try less frequent injections.

Hope this helps.

Hope this helps and hope u feel better soon.


Thanks Ryan,

Thats really nice to know. Since i had that chest pressure feeling the last time, i havent had any B12 injections, and i havent had any chest pressure.

What is you symptoms on B12 deficiency ?



Luckily compared to other peoples I have read on this site my symptomns are not too bad.

I had total fatigue all the time, bone pain (lower back/hips felt broken. Also had bad pain in back of my heels, lack of concentration, felt really depressed, couldn't eat properly(very slow digestion, felt full and bloated with very small meals, a lot of numbness in whole body.

Overall I didn't feel very well at all.

Luckily I had a blood test and b12 was very low so my GP put me on B12 shots(1 shot a week of 1ml hydroxocobalamin for 6 wks). I felt a lot of difference in all of my symptomns so GP carried on 1 injection weekly over a total of 12 weeks, then reduced to 1 injection a month for 3 months, then 1 shot a month for next 3 months.

I felt alive again.

GP tried 3 shots a week(one every other day) and that's when I got the tight chest and palpitations so I cut down to 1 shot a week.

B12 is an energy boosting hormone so I had a feeling it was that which causing me those symptomns due to too much too sudden in my system.

It's like overdosing on caffeine.

I'm sure if you cut down the frequency of shots your symptomns will go.

You have to take Folic acid daily if you're having B12 shots.

Sorry I wrote a lot more than what you asked but I thought it might help you understand better.

Introduce B12 in your system more slower.

I hope it helps.

Don't worry, your symptomns will go and it takes couple of months for B12 for you to notice good improvement. It took me about 3 months.

I hope this helps and wish you well.

Don't lose hope or stress about it, give it time and you'll feel much better !

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