When did you start to notice a difference after receiving B12 injections?

I know the general advice seems to be that everybody is different but I just wanted to hear about others experiences with the b12 injections like how long it took to help symptoms, what symptoms they actually helped and also what level their b12 was at the time of injection.

I'm getting my first b12 injection tomorrow and I just though it would be interesting to hear other peoples stories.


17 Replies

  • My initial diagnosis was: 2002 (Jan) MCV 105.5 Hb 132 serum B12 86 ng/L = 63 pmol/L. I got not standard loading, I got one B12 injection a week for 6 weeks, then one a month for 3 months to then go onto once every 3 months. Initially I went back to GP saying are you sure you've got this right these B12 injections are doing nothing, to after some 3-4 months feeling the improvements (far more energy, feeling of being awake again, being able to see more clearly, as if a fog had lifted). I from then on started to rely on B12 giving me energy and keeping me awake! Marre.

  • Marre

    Are you saying you only get injection every 3 months and that is enough to make you feel good ?

  • No, over time I started to lose one month out of 3, back into foggy weak existence, saw haematologist/ neurologist, diagnosed with sub acute degeneration of spinal cord and folate def (2005-6), got NHS B12 once every 2 months, learnt to self inject, add my own B12 (cyanocobalamin) once every 2 weeks now to the NHS prescribed hydroxo once every 2 months. My serum B12 dropped on standard treatment (2005 B12 230 ng/L = 170 pmol/L.) It now stays just over the 400 ng/L. I also now know after seing a gastro that I have an abnormal terminal ileum, with bile salt mal absorption and that will affect absorption and recycling of B12) Both my daughters seem fine on standard B12 every 3 months though. Marre

  • Thanks for the reply :) Hopefully they'll work for me soon too

  • Hi

    It was about two weeks before I felt any improvement from the loading doses. In fact the weakness and fatigue got worse before it got better; in addition I developed spots on my chin and a very dry mouth. My first symptoms to improve were the headaches and tingling in hands and feet. Then I realised my mood had improved and gradually my energy (well some of it) returned. My b12 level was less than 30 (below a recordable level apparently). However like you say we are all different. Some people report improvements after just a few hours.

    I hope all goes well with your first injection tomorrow and you feel some improvement very quickly.


  • I am so pleased you started this post as you have saved me starting one. I had my 6th loading dose yesterday and I have convinced My doctor to give me 3 more another week. After my first 2 I had more energy when I woke up in the morning but now I am feeling more tired than and exhausted than before. Falling asleep at 8 pm in the evening amd my legs feel so heavy and ache. Has anyone had this experience.


  • Thanks for the reply :) I have heard a few people feeling a bit worse for a while after they get the injections but eventually it is supposed to go away. Hope you start to feel better soon and that the extra injections help

  • Thanks for the reply, I got my first injection today and my nurse said the same thing really that most people only start to feel better after the first 2 weeks of injections. I can't believe your level was <30! Hope you are feeling better now

  • My B12 level was 160.

  • I was diagnosed in 2012 and my B12 was 75ng/l . I had been ill for years with stomach trouble and all manner of weird symptoms - palpitations, muscle weakness, tingling, fatigue, mental fog - you name it ... - all due to the PA - but originally misdiagnosed as acid reflux, hiatus hernia, depression etc. Last endoscopy showed I have atrophic gastritis. My loading dose was 7 jabs - 6 initially but when i still felt bad I got one more. Then I went on to 3 monthly jabs which was awful - I felt unwell after 4 weeks - that went on for a many months. Then she let me have them at 8 weeks and I was still finding it hard to cope . After a year of struggling I now get them monthly. It is just over 2 years since diagnosis (but I am sure I have been ill for more than a decade) - I am feeling better mentally but still get symptoms returning after 4 weeks. I have always been very active despite being nearly 61 and have recently learnt that the more you exercise the faster your B12 is used up. I now supplement with sprays and sublinguals. I still get pins and needles in my hands and feet , have a numb toe and get phases of extreme fatigue. I have learnt to supplement my iron also as I have low serum ferritin much of the time. I take iron for a month every now and then and also take a daily folic acid of 400mg (the recommended daily allowance). Some people get very low on folate and iron so it is worth your doctor checking that.

  • Thanks for the reply, Its weird you mention stomach problems because I've had them too along with IBS and I was also diagnosed with a hiatus hernia a few months back. I also have the palpitations and muscle weakness but I've been lucky to never get the pins and needles and I've never had that much numbness. My dr has checked my folate and iron and they seem to be okay. I'm glad you've found a routine that works for you :)

  • Perhaps stop the folic acid, replace it with the more bio available folinic. Folic acid can cause blockages in your system. Please research this

  • Great post, I'm 8 days from getting my 5th monthly injection, I had no loading dose as my Dr was not au fait with procedure, at the time I was happy to be getting any injections at all and didn't query it. My history was Graves disease 9 months after birth of last baby 11 yrs ago never sprang back after that, endo said I'd just become unfit through being ill and to go away get fit and I'd feel better!! if only I knew then what I know now! anyway I went through patterns of feeling relatively ok then crashing, went to GPs various ones at surgery they said bloods all ok and one of them eventually convinced me to take anti depressants even though I was in pieces begging her to listen to me that I didn't feel it was depression, I just knew there was something else. I took the tablets for 18 months they made no difference! it got to another few trips to drs and me joining a running club and nearly killing myself to get 'fit' still to no avail. By this point I thought it must be M.E as I hadn't died and it had been 10 yrs so it couldn't be some hidden cancer! I then did something really silly and went on a boot camp class with a friend thinking i'll give it one more chance at getting fit! I was in bed for 2 weeks with a fatigue that was like nothing you could explain, I just felt plain ill. I begged my Dr to refer me to the Essex M.E/CFS clinic where they diagnosed me with M.E and I started on a Graduated Exercise Therapy this went on for around 8 months and it did suit because I paced myself well. Then the worst or best thing happened, the Dr and the therapist got 'asked' to take garden leave, I think something to do with an article they wrote on BMJ!! Wont go into that but left me thinking I couldn't trust any medics I was so worn out so I went to surgery and asked for my blood results from the last year- to be referred to cfs clinic the GP was asked to do a number of tests which included vit D b12 magnesium and zinc when I looked at my results my heart nearly stopped. Vit D was 37 and in the insufficient range (lab had pointed this out) magnesium and zinc although in range were only just, b12 was 320. How could a specialist have diagnosed M.E with bloods like that? At the time I thought it was my vit D so I self treated but made no difference so went back to drs asked for new bloods he agreed. By now i had developed headache, earaches, tinnitus, pins and needles and my lower back had been bad for around 5 yrs, ridges in nails no moons basically nearly every box was ticked for b12 def. Got phone call from the other GP I thought great they've noticed the low b12 which was now 220 with mchc just on the high side. No they were concerned about my cholesterol which has been creeping up! I said well I'm concerned about my red blood cells and my low b12, to be honest I think she was surprised I even knew that much and offered a trail of b12 injections which is where im at now. i was doubting the whole thing this week as for the first 3 months my improvement was like a miracle apart from the 3rd week when i counted the hours to the nxt jab but this month i have felt so tired again and had some tingling and headachy. so reading the above has made me feel better as this obviously happens, maybe if you have more stress or activity in that month?

    sorry if that was a long post i never was very good at keeping it short and sweet!

    I was told this week that my local haematologists wont do any further testing as i was in the grey area! Seems this is par for the course and I've had wonderful support from everyone on here and am now determined to self treat if i need, to get as well as i can. also learnt from here that testing is pointless once you've started treatment unless you stop treatment first and im not doing that! so i will work it out through trial and error and reading other peoples stories and knowledge.

  • Thanks for the reply and don't worry the longer the post the better! Its interesting hearing other peoples stories. I've had symptoms for about 9 years now but its only been the last few years where its gotten worse and my b12 has been low for about the last year (they only decided to start looking at it a year ago). Its annoying as well because they've put me on injections without actually testing for PA, by coincidence I had an appointment with my gastroenterologist 2 hours after my injection at the GP's and asked them to test me for it. Hopefully just 2 hours won't make too much of a difference, the doctor seemed to think it was worth testing anyway but who knows how valid its going to be now.

    Have you tried getting the active b12 test done for a definitive answer? I hear a lot people do this and it helps them get further with their GP's.

  • About the same as me then, my b12 only 1st looked at just over a year ago, I had been having stomach issues for around 5 yrs as well but completely changed my diet and started using probiotics and that seemed to calm that down somewhat, id began to think I had a stomach ulcer some nights- hopefully your tests will yield results in your favour, which test did they do? I'm going to read up more on the active test as it could be worth doing if it will mean keeping gp going forward.

  • I think the active test is more available now- do you know with the active test if it is irrelevant if you've started treatment? As it only checks for active b12 in the serum. You went through a lot just to get them to let you have the injections I am so glad my dr agreed to the trial jabs, although I think this must have been due to having nerve issues? My pins n needles were the last symptoms to develop after heart palps and nightime racing heart, the worsening of symptoms definitely seemed to coincide with dropping b12 levels so you did the right thing by keeping an eye and forcing the issue so to speak..Good luck...

  • My b12 is 95 and my folate is 2.78 I feel so ill and extremely weak all the time been told by my doctor I need a first dose of b12 in the form of 6 injections then once a month

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