Can taking too much B12 cause you tiredness/fatigue ?

Hi, I've been reading the posts here and have learnt a lot about B12 defficiency.

I've had my 6 loading doses of B12 (1 per week) and then been having 1 jab every 2 weeks, so about another 8-9 jabs since starting 29 Aug 2016 until now. I also take Folic Acid 400ug daily.

I felt fine energetic after 8-9 jabs and recently been feeling fatigued in the evenings.

Do I need to cut down, is it due to having too many/too frequent jabs ?

Has anyone had this sort of experience.

As it usually helps you to also sleep better at night, is it possible too much can cause you to feel sleepy or tired much earlier ?


20 Replies

  • Hi Ryaan

    I doubt very much that you need to cut down as you cannot overdose on B12 as it is water-soluble and any excess is excreted via urine.

    Ups and downs along the way are very common.

    But to give people a better picture, perhaps you could say where you are (country), and what type of B12 you are using - Hydroxocobalamin, Cynocobalamin or Methylcobalamin.

    The number and frequency of your loading doses and ongoing jabs appear to differ from the usual regime used in the UK, for example.

    Different types of B12 tend to be used/favoured in different countries

    Have you formally been diagnosed with Pernicious Anaemia or another form of Vitamin B12 deficiency? Do you have any other related health issues such as thyroid conditions etc?

    This information will help the wonderful people here provide you with more specific advice.

  • Thankyou

    I am in UK using 1ml Hydroxocobalamin. Diagnosed with very low B12 with a long list oc the common symptoms. Not diagnosed with PA.

    I don't have any other that I know of like Thyroid etc.

    My regime is different from the usual UK of B12 jabs as my GP put me on 1 jab per week for loading to introduce the B12 a bit slower as 1 every other day (3 per week) I had a problems(breathing/heart palpitations).

    As I've had loading doses once before and then 1 every 3 months, which didn't work as I knew I needed more frequent jabs but GP didn't agree so this time I decided to take the SI route( as needed) which felt every 2 weeks as 3rd week I could feel symptoms coming back.

    Now I was thinking to cut down from every 2 weeks to every 4 wks as I haven't had any other symptoms return. Now it's just this tiredness and fatigue kicked in.

    So a bit confused.

  • No, it can't. What often happens is you need more as you feel better as you start to do more and use it up quicker!

    You will also need supporting supplements to make the extra B12 work properly: a broad spectrum multivitamin and mineral supplement plus extra folate, potassium and magnesium, maybe iron. I suspect you may need more of one or some of these.

    For more information you could look up my profile by double clicking on my name and see my reples to others on the subject.

    I hope you find the right balance and feel better soon. If you think you have taken everything you can and are still getting worse then you should get other things investigated, including thyroid problems and a significant vitamin D deficiency.

    Good luck!

  • Thankyou, I will take a look. I'm only supplementing with 400ug Folic acid 1 daily and high dose D3 twice a week since starting the B12 jabs.

  • I suggest you Google deficiency and excess of the supporting supplements I mentioned to give you an idea of what you might need to take, based on your symptoms.

    I am not trying to give specific advice, but to me, just based on experience, I suspect that you will get a significant improvement from increasing your folate (vitamin B9) levels by taking extra folic acid. This is very safe, like the B12, and so can be trialled and to give you an idea, the recommended rate for people injecting every other day or more often is 5 mg (5000 mcg) per day.

    It may also help your feelings of anxiety.

    I hope you feel better soon.

  • Ryaan , Deuto and deniseinmilden

    Some people respond to high levels of B12 in serum by generating anti-bodies that prevent the B12 getting through to your cells, leading to a functional deficiency. So, strictly speaking it is possible for some people to have too much B12. However, this reaction would have been kicked off by your loading shots so not likely that the crash is the result of the frequency of your injections. In fact the most effective treatment for functional deficiency seems to be more frequent B12 so that there is too much in your blood that it can't create enough antibodies to stop all the B12 getting through.

    So, unlikely Ryaan that your crash is caused by injections being too frequent. It may just be part of the general ups and downs of recovering - and doing a lot physically can deplete B12 levels - or it may be that there is something else going on as well, eg vitamin D, iron deficiency or thyroid.

  • Thank you Gambit!

    While I haven't been tested for functional deficiency this is by far the most likely explanation for my problems. Thank you very much for reminding me about this. I realise I must be more cautious and try to remember all aspects of something before replying on here.

    (I had food poisoning 3 weeks ago and it's upset all my levels of my supporting supplements and amino acids, resulting in setting me back 8 to 10 months, to when I was really struggling, with significant memory and executive function problems. I wasn't taking account of this enough, sorry.

    At least it has shown how far I had come!)

  • nobody can remember everything all of the time - I know I don't

    Hope you get back to 100% soon.

  • Do you know if your other levels are OK? For example VitD, folate, and ferritin. You could be using up all your folate to process the B12 you are injecting. This is then leaving you low, and feeling tired.

  • Vitamin D was on the low side so I'm supplementing as GP didn't give me anything. I was low on Folate, currently taking 400ug Folic Acid since start of injections. Ferittin I don't know as GP didn't give me anything.

    I think I will ask for copy of blood results.

    Thanks ver much.

  • what dose of d3 are you taking and it is best to take d3 with k2 in it and also take with fish oil and sometime zinc at the same time....

  • D3 20,000 IU (500mcg), I took 1 box (20 capsules), 1 tablet twice a week as that is what my GP game me last time I was low.

    Now on 2nd box taking 1 per week. I don't know if it's enough but didn't want to overdo it.

    Only other thing I'm taking is Folic acid 400ug 1 daily.

  • Another suggestion is that you may feel sleepy because your body is healing and needs rest to do that properly. We can all tend to fall into the trap of thinking with the right medication we can recover instantaneously and bounce back into a high level of activity, but in my experience often we need time and extra rest to fully recover from illness. I know it's several months since you began treatment, but it's still possible that you may have ups and downs.

  • An expert Doctor in the field of B12 deficiency told me that treatment of a deficiency with B12 can lead to a reversing out syndrome, whereby all the symptoms you experienced from being deficient reveal themselves as your body starts to heal from the deficiency. So if you are very deficient, you could get awful symptoms for a while. I know I did. It can be a bit scary though! Take care, listen to your body and let it heal.

  • I definitely felt tired and listless after my loading doses. I also had some breathing difficulty and dizziness for a while. I personally think this is caused by the body healing after so long without enough B12. Just think of how tired you can be after a major illness while your body recovers - I think this is the same as regeneration used up a LOT of energy. I imagine the fatigue levels are linked to the severity of the deficiency and whether there was nerve damage too.

    However, I would still ask the doctor about it. The advice on here is great, but no two people are the same so I would always consult with my doc when possible.

  • I agree. There is also the small chance that some people can't convert it from hydroxycobalamin (given by the NHS) to methyl cobalamin which is the form the body needs (I think, although don't quote me on this).

    Ryaan-Have a look at the great website of the charity where there is lots of info here to help you! 😊

  • If you can't convert from hydroxocobalamin to methylcobalamin it would show up in infancy.

  • I'm using Hydroxocobalamin. It's not that I'm not getting enough, what I'm saying is am I getting too much of it. I felt much better after loading doses especially after 8-9 jabs and as I have continued SI 1 every 2 weeks after loading doses up until now, am I getting too much B12 which is now causing all the fatigue.(if I understood your answer correctly)

  • people do vary in what forms of B12 suit them best.

    not aware of any evidence of people who can't convert hydroxo/cyano to methyl, though this process may be less efficient in some people, so may need more hydroxo/cyano than others, beyond those mentioned by fbirder who have a genetic variant that affects them from birth - fortunately rare as it is a serious condition

    there are 2 forms of B12 used by cells for different processes - methyl and adenosyl. there are some recorded incidents of people who cannot convert methyl to adenosyl.

    also not aware of any reported cases of people who can't convert hydroxo/cyano to both methyl or adenosyl as required.

  • there was a huge documentary I watched yesterday about polyphenols giving you energy back, youth, lowering cholesterol, even weight loss discovered by a dr in California who was a heart dr that had a patient that used it and shocked the dr and the dr did a 10 year study and now says everyone should take polyphenols from fruits like cherries, berries, etc or supplement for energy...I have blueberries in the freezer I grow myself so I did a smoothie last night after seeing this and shocking today my fatigue was gone and I have been so fatigue for so long I was dragging myself.....the dr said he was the most shocked....a guy in 4 months lowed the cholesterol in this arteries in half......if you google may come up...

You may also like...