Pernicious Anaemia Society

How soon should you feel results?

I have been having B12 shots every other day for the last 2 weeks, & also liquid iron, when would you normally feel a positive change?<br />I have not been diagnosed with PA, just severely iron & B12 deficient.<br />Due to the same, I had to have a blood transfusion a year ago, and I felt so much better immediately.

4 Replies


It seems to depend on the individual, some feel better in no time; others it can take moths to feel the benifit of the B12. In general I believe it can take up to 4 months for all bloodcells to be replaced by new ones so that seems a logical guideline..and it depend if all other issues are sorted, say if you also are folate def but not treated then that will put recovery behind etc.

I initially went back to GP saying are you sure you got this right I feel no better, but some 4 months later I realy did and started to depend on the B12 jabs to feel well.

Kind regards,



Thanks Marre,

Just so nice to have an idea, from someone who has been through it!

I would really like to join the PA Society, just so I could have access to more info, as there is not much out there. But as I have not actually been diagnosed with PA, probably not a good idea.

Hopefully having a blood test Tuesday, to see if anything is happening.

I think they plan to stop the jabs then anyway, as there seems to be no improvement.

I am not sure about the folate, they won't let me have a copy of my results, so I don't know specifics of what they are testing, or what the actual results are.

All I get is "you are severely iron & B12 deficient" lol

Thanks again



Do join the PAS forum!! There are loads like you , re:". But as I have not actually been diagnosed with PA, ", to be honnest it is very difficult to get a PA diagnosis, I'm a "most probaly PA" by neurologist, a "defenite PA" by GP and did test positive for antibodies to IF but only in the "normal" range of the my diagnosis is more a most likely as my father 2 of his sisters, his mother and now both my daughters were/ are on B12 replacement...

I did not test positive for AntiP cell antibodies so what ever we all are on B12 treatment, def for some reason and the options as to why are so large and so complex and many not understood or researched well, anything can still go wrong after that B12 jab, there are numerous genetic reasons or other reasons why the injected B12 is still not transported or converted into what we need..

You have a right to your bloodtests unless your GP deems it harmful to your health to see them...Freedom of information act...


Marre's right. My GP always gives me copies at each do the Hospital Drs.

You shouldn't need to cite the Freedom of Info act's data about you an as such you are entitled to a copy without the FOI. Simple Subject Access Request covers it.

If there is anything "medically" sensitive and a GP doesn't think you can "take it" then I'd be rather concerned...



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