Is it just me: I have just had the fifth of six... - Thyroid UK

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Is it just me


I have just had the fifth of six booster injections of b12.

I have felt unwell since starting them , bad headaches, flu like aches and pains .

Everyone who is having them seem to feel a difference after the first shot. I haven't seen anyone say they felt unwell.

Is it just me?

I am on 100mcg Levo at the moment. I had wrist pain Etc on that, but nothing like this.

Is it just me?


17 Replies

Pinkpeony, I've seen posts where people don't see any benefit for weeks after completing the loading doses.

This link explains what to expect after B12 injections

gabkad in reply to Clutter

Clutter, I have read that some people can develop an adverse reaction to the shots. Like an allergy type reaction. Inflammatory cytokines = flu like response.

Could be this person would have a less adverse response to sublingual 5,000 to 10,000 mcg doses of methylcobalamin.

Pinkpeony in reply to gabkad

Hi Gabkad

I read your post to Clutter.

Last jab tomorrow, so hopefully back to what passes for normal these days :·)

Cheers Pp

Allyson1 in reply to gabkad

I had adverse reactions, but I was started in 5,000 mcg methylcobalamin sublingual daily for months, along with 1000 mcg methylfolate.

I had full body swelling, flu-like symptoms, joint aches, muscle aches, migraines, cystic acne, burning skin, confusion, mood swings, anger, paranoia, fatigue, a great deal of palpitations, tetany, spasms, diarrhea, high inflammation...

I can't say exactly why I had all the problems. I don't necessarily buy the detox explanation.

I have since found that I had hypokalemia initially, hence the palpitations, tremors, spasms.

I had small intestinal bacterial overgrowth, and I do wonder whether the bacteria was taking the b12 for itself, or being fed by excess b12.

I was also probably hypothyroid. I also had problems regulating blood sugar, which got worse. I had lowered adrenal function and have celiac.

I'm not entirely sure if these factored in but suspect they are relevant.

I stopped b12, thinking I was overdosed, and became deficient to the point of neurological damage. 

Started on shots this time, and tolerated them better. I had deep joint aches after shots but those only lasted days. I still get a rash. Other than that no problems. The one major change I had made was diet.

EDIT- somehow I thought this was on my newsfeed but it's 2 years ago. Leaving it anyway!

Pinkpeony in reply to Clutter

Thanks Clutter. I had a look at the POSSIBLE side effects of these jabs,and there is a pretty comprehensive list.

I guess I am one of the unlucky ones.

Last one tomorrow T G .


Clutter in reply to Pinkpeony

PP, you may get more advice from the HU PAS forum re side effects etc.

I had such awful reactions to the 6 B12 loading shots back in 2012, that I haven't dared have the 3 monthly maintenance shots. (I wrote about my reactions in detail on this forum a while back but don't know how to retrieve the posts). It's taken 2 years for my B12 levels to drop back to the deficient levels they had been, and some of the neurological problems are recurring so I really do need to find a way that is safe for me to raise the levels again.

My GP said that she hadn't heard of any adverse reactions to B12 injections and has suggested that I take pills instead. Unfortunately these didn't work before and I doubt whether they will ever work as I have pernicious anaemia. It is frustrating as, having experienced the same problem as you, 2 years on I still have no answers. The only positive thing that happened as a result of the B12 injections was that after 2 months of having them, practically ALL of my neurological problems (loss of sensation in fingers and toes, numb palms of hand, persistent muscle tics, loss of balance, constant sensation of vibration, carpal-tunnel syndrome) went and have only started to creep back slowly in the last few weeks. I'm wondering now whether the severe pain the B12 injections provoked was actually the nerves starting to feel things again as they repaired?

Pinkpeony in reply to lemurtail

Sorry you have had so much bother with b12.I was hoping that maybe tablets would be better, but obviously not.

Is it just one injection you get after 3months?

I feel stupid when the nurse asks brightly ' are you feeling better' ?and I have to say, no not really!

The doc said I would feel like a new woman or not as the case may be.

Pity, I think my hubby was hoping for the former lol.

My best wishes to you


Hidden in reply to lemurtail

Hi Lemurtail, I realise it's been a while since you wrote this post but all your nerve pain symptoms are the same as mine which I've had for the last 3 yrs my hands have suffered the most, I've had CT surgery on both, thumb joint replacements on both & 2 nerve release ops on cervical spine the last one in Dec, disk removed & a cage fitted, & still have pain & stiffness? I've now got hypothyroidism, low iron which I've had for years, low Vit d & b12 is bottom 200 ng/l and like you have even more pain & what feels like strangulation of the vains & tendons, when ever I take supplements. Can you let me know how you are now? & if anything helped? Wishing you well. 

lemurtail in reply to Hidden

Sorry for taking a while to reply. I'm feeling surprisingly well these days in spite of my thyroid blood test results suggesting that I should be barely able to function! In my case  the B12 injections proved to be the turning point. I'm now back on them again as I started to get certain easy-to-ignore (as they weren't particularly troublesome) symptoms back again. These were an irritating eye tic and a sensation that the ground was vibrating. Blood tests showed that my B12 levels had dropped again over the years I'd been too wary of going back for regular shots, after my initial woes. Fortunately, this time I had none of the disturbing side-effect reactions that I'd suffered the first time. Within the week, the minor tics and vibrations went away and have stayed away. Clearly the B12 injections ARE beneficial in protecting my nervous system. I wonder whether the pain I'd experienced with the first loading shots was my nerve damage starting to repair itself. I now have full sensation returned to my hands, fingers and toes. The mysterious carpal tunnel issues also vanished. :-(

However, the operations you have had, seem to relate to arthiritic and bone inflammation issues - something of which I have no personal experience. I don't know if this is relevant but one of my friends has PA and ankylosing spondylitis (inherited from her mother). She's had to have a couple of her lumbar vertebrae fused surgically as the bone had eroded so badly. She says that her B12 injections help alleviate the exhaustion she has from the pain she's in. The painkillers she's on, and the heavy-duty antacids to counteract the severe heartburn caused by the painkillers, mean that she is unable to absorb nutrients properly. Her GP prescibed the B12 injections for her because of this. Ironically, she now has osteoporosis because of her vitamin and mineral absorbtion issues - and the osteoporosis is worsening her arthiritic problems. Vicious circle! :-(

It could be that your body is reacting to one or other of the filler ingredients in the supplements you tried. The ones I have reactions to are lactose, maize starch and aspartame - not that my GP believes me! Alas, you have to search far to find supplements and pills which are free from these.

Good luck

I was told that with pernicious anaemia, I'd have to have a B12 injection every 3 months just to keep my levels up, and this regime would be for life. My mother has the same conditions - hypothyroidism and pernicious anaemia - and she has no problems at all with the injections. She actually IS much better, and instantly so, as a result of them, However, she starts to get ill again about 3 weeks before she's due her shot. Makes me wonder whether the treatment regime should be adapted for people so that they can have less-frequent or more-frequent shots depending on their individual response.

I think that it takes several weeks after the initial loading doses before someone can expect to see a benefit as it takes a while for the new blood cells to develop. Whether the experience of feeling worse before this happens is a common experience, I cannot say.


Gosh, it would put you off somewhat, to having any more shots.

But you don,t really have an option, do you, it is the only way to get your B12 deficiency corrected.

I have heard that you can get pain after the shots and that it is just the body wakening up again.

Can you try a different B12, perhaps Methylcobalamin, that is, if you have used Hydroxocobalamin, last time and vice versa.

Perhaps it was also, because you were so, deficient.

You could try asking your GP,if possible to give you half the dose, so doing it more slowly over an extended period of time.

All the best.

Pinkpeony in reply to Hidden

Hi manukia.

This is the first time that I am on b12 and I wouldn't have known if the good folks on here said to ask the doc for some blood tests.

I was completely out of the range so it's no wonder I felt so unwell.

The jabs are hydroxocobalamin. Will see doc at weekend to find out what happens next.

Thank you for your post

Best Wishes pp

Hidden in reply to Pinkpeony

I to, only found out about B12 deficiency from this forum, I have already recommended

the forum to several others.

I self inject tomorrow, for the first time, so I am quite nervous.

I hope you get to the bottom of this soon.

Take care


PP - how are your other vital minerals, especially irons & Vit D3?

My colleague's mum (who has PA) had to delay her injections until she could get her Vit D level up enough, as the doc said they just wouldn't work.

Just a thought. J :D

Pinkpeony in reply to Spareribs

Hi Sparerib. I was given ferrous fumarate as my ferritin was very low. I have no readings for vit d but have been taking fultium 800 as prescribed by Endo.

As I said in the previous post, Thank goodness I found this site.It's a pity I hadn't found it before my last appointment with the Endo.

Cheers pp

Spareribs in reply to Pinkpeony

First - it is important that you get your calcium tested as VitD affects this (Vit D supplementing not recommended if high calcium levels).

I test first, then supplement Vit D (Sept to April) I find 4000iu a day suits me (biocare drops) - your fultium is 800iu. I suspect your Endo would not have prescribed it without a test first, please ask them for Calcium & Vit D results. Also folk with low B12 have digestion problems inc absorbing pills.

I buy my private VitD test here (NHS lab) - I'm ringing tomorrow as I am aching again!

A previous post may help...

Cheers too! J :D

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