B12 loading doses no difference - Pernicious Anaemi...

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B12 loading doses no difference


Hi, two weeks ago I was told I had b12 deficiency and have since had the six loading doses. I had another blood test today, the one to check for antibodies so awaiting results. Just concerned as my symptoms haven't changed since the doses, I feel maybe 10% better as my mind is less foggy than when I was diagnosed but other symptoms are the same. Has anyone else experienced this? Do you have any advice? Thanks.

11 Replies

Have they tested for anything others deficiencies, folic acid thiamine electrolytes etc? We're your blood cells enlarged? It can take a while to work 2 weeks isn't long enough. Some people it works straight away, others have a honeymoon then it goes bad again etc I'm no doctor but feel for anyone going through this, you are not alone X

clivealiveForum Support

Hi Hidden It is not uncommon for some symptoms to appear to get worse before they get better once treatment has started whereas (as in your case) some improve quite quickly.

A lot will depend on how low and long the B12 deficiency is and there is no fixed timescale as we are all different.

If you are still experiencing neurological symptoms you need to ask your doctor to continue the loading doses "until there is no further improvement" in accordance with the N.I.C.E. guidelines on the treatment for B12 deficiency.

Click on the link, then on "Scenario: Management" and scroll down.


You also need to ask your doctor to check your Folate level as this and B12 helps your iron to make red blood cells. It may mean that you need to supplement with folic acid.

Do you have any idea why you became B12 deficient?

Let us know the results of your Folate and the antibodies test.

I am not a medically trained person but have had P.A. (a type of B12 deficiency) for more than 45 years and I wish you well.


if your symptoms were due to anaemia (larger rounder red blood cells) this takes a few months to correct as healthy new red blood cells are only created as your old red blood cells 'die' and they tend to live for 4 months.

Please be aware that if the IFA test comes back negative that doesn't rule out PA as the cause of the deficiency as it tends to produce false negatives 40-60% of time. It can also produce false positives if done too close to an injection - but how close depends on the testing method and the time difference is much lower - think its down to a day/two - if it is one of the more modern tests.

The nurses doing my loading injections kept asking me if I was feeling any benefit from them. I have to say I felt nothing at the time, it took a while for the effects to be felt. Probably things actually were more painful while the healing process was starting to work.

I really began to notice a difference some months later. I think it probably took nearly a year to really feel well again. I've heard this can be due to the amount of time your B12 was depleted. The longer it was left untreated, the longer it will take to heal.

What are your symptoms and how long have you had them ?

I found no improvement with any B12 injections after my loading doses. I continued to SI for several months on alternate days and continued to feel exhausted. I even gained more weight! It was horrible and I stopped. I didn't feel better energy wise until I started taking NDT (thyroid medication) and even then, it's been hit and miss. Lots of people find it takes months to recover so don't lose hope yet - here's to you recovering soon x

If it helps, my neurologist told me that it could take 18 months or more to begin to feel closer to normal. In my case, that was a pretty accurate estimation. I was out of work for a year and half before I felt able to hold down a job again. And, I could only handle part-time work for another year. Now I'm up to full-time. But, some symptoms remain even after 7 years, I've just grown used to them.

Hi cristjams

Mind my asking you which signs and symptoms you are left with?

Thank you .

Gambit62Administrator in reply to avocadopeardrops

avocadopeardrops, you have replied to the post rather than to Cristjams comment so Cristjams may not be aware that you have asked a question so mentioning him now


Thank you everyone, yes they've tested folate and that came back ok which I'm thankful for. It's good to know symptoms take a while to get better and it's not just me, as I was worried the injections haven't seemed to have helped much physically at all. Once I know the results of the antibody test it will help know how to treat. I will maybe mention to GP about more loading doses until 'no further improvement' perhaps that will help. Thanks :)

I agree with everything Clive Alive says, it takes time. I was on loading doses every other day for 12 weeks! Only because I am a nurse and pushed my GP to refer me and fortunately and on-the-ball haematologist (there are not many) said "get going with this treatment!". Re the anti body test, just to say it is NOT accurate only about 50% sensitive. So if you test negative, this doesn't mean you don't have PA 😊

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