B12 loading dose jitters : I was given... - Pernicious Anaemi...

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B12 loading dose jitters

Moobear2 profile image

I was given the loading given the loading dose of b12 injections. After the first few I felt jittery. But after the last dose I felt unwell. I started getting chest pains, palpitations and feeling anxious which I didn’t suffer from before the shots. Is this normal? And how long did it take to disappear. I had the last loading dose 3 weeks ago and definitely feel the symptoms have Eased but not gone completely.

42 Replies

Yrs I felt more ill on loading doses.and afterShook up my whole nervous system.

Akso headaches abd tinnitus.

It does get better.

Hope it's helped other symptoms you had.

Waking up nerves ect .

How long unt your next b12 injection?

Moobear2 profile image
Moobear2 in reply to Nackapan

Thanks for the reply. I was told I would need it every 3 months for life. But I ended up in A and E with the palpitations chest pains. They took bloods which said I was over on my b12 and suggested I probably wouldn’t need any more so not sure as not been back to doctors

clivealive profile image
clivealiveForum Support in reply to Moobear2

It is not uncommon Moobear2 and your B12 levels will obviously off the scale and any excess will be excreted via your urine so don't worry.

The B12 is repairing the damage done to your nerve endings caused by your B12 deficiency so your brain is getting signals from places it had forgotten you had got.

Check with your doctor whether your folate level was checked before the B12 treatment started. It may be you need to supplement with folic acid but ask him first.

I am not a medically trained person but have had P.A. (one of the many causes of B12 deficiency) for nearly fifty years.

I wish you well.

Moobear2 profile image
Moobear2 in reply to clivealive

Thank you for the reply clivealive I know they checked iron levels as was also supplemented for that and again at A and E also said these was above normal levels.

They couldn’t work out how both had gone up so quickly as only just finished the loading dose and only been on iron for 3 weeks. Both levels was above average.

I will try. My GP haven’t been the best.

I’ve also lost a stone in weight since the b12 shots. Lost complete appetite but my GP basically told me to get on with it.

I will try to see if they will check folate levels. Thank you for the advise.

Nackapan profile image
Nackapan in reply to Moobear2

I ajso lost just under a stone in weight on loading doses. I was eating alot though as brought to me in bed. I put it all back on so once you are on your healing yiu will too.

I think the b12 speeds up your metobolism initially in the rapid increase of b12 in your system.

Hope you are dealing with any other symptoms going on.

Its goid your levels have raised.

Yiur body will be working g hard processing it all

Hope you start to improve soon

Moobear2 profile image
Moobear2 in reply to Nackapan

Thank you feel so much better knowing this isn’t just me. I went to the gp with my symptoms and basically said it was in my head.

Nackapan profile image
Nackapan in reply to Moobear2

Shouldn't go on numbers .Should ho on Symptoms

Hope your heart and you checked out in A and E and you are okay.

I also ended up in A and E with foul neurological symptoms snd unable to walk early on.

Had a brain CT scan and heart obs ect.

Before I knew about b12 deficiency.

Underestimated how ill you csn get!

They thought I was on recreational drugs as pupils dilated in a bright room!

B12 was later tested at Gps.

Hope you start to improve soon.

Moobear2 profile image
Moobear2 in reply to Nackapan

Yeah they did a ECG which was fine. My heart rate was just really high and my blood pressure was up. Other than that they couldn’t find anything wrong with me and sent me home. The first week I felt really unwell. But all my pre b12 symptoms went straight away. And gained the new ones of the jitters, chest pains and really strong palpitations.

Just don’t like the feeling of it.

I ended up in a and e as I thought I something was wrong with my heart.

Thank you.

Rocky profile image
Rocky in reply to Nackapan

That's interesting to read about your pupils being dilated, as they told me the same last year in A and E. I had to go in as both my legs went numb and I couldn't walk. They thought I had had a stroke and were going to do a CT scan. Eventually I saw one of the A and E Doctor's that understood b12 deficiency and neurological symptoms and he agreed to give me a b12 injection. I also had to go back for an MRI scan to check for damage to the myelin sheath and luckily I don't have any. I am now on 4 weekly b12 injections after arguing with another A and E Doctor about my diary of symptoms I had been keeping, and my symptoms kept coming back after 4 weeks

Sallyannl profile image
Sallyannl in reply to Rocky

I had Dilated pupils and paramedic insisted I was on drugs. Told him I had never seen a drug in my life 🤪😂

Rocky profile image
Rocky in reply to Sallyannl

It's unbelievable what they come out with. They didn't say that to me, they were just concerned that they were dilated

Nackapan profile image
Nackapan in reply to Rocky

That's good.You saw a good doctor.

They sent me o my way undiagnosed saying I'd had a panic attack.

Wax pleased I hot the Ct scan though.

Thsg was because of a fall i got it though.

Rocky profile image
Rocky in reply to Nackapan

I only got to see someone as I was taken in by ambulance. I have found that since being on 4 weekly injections my eyesight has been so much better. I wear contact lenses and glasses anyway, but was finding my vision going blurry before my injection was due. I don't have to wear my reading glasses for my laptop anymore. I wish you well too

Nackapan profile image
Nackapan in reply to Rocky

Oh I did see 3 doctors I'm a and e but nor one as well informed as you saw. I. Back to my usual prescription but unable to use a laptop yet or read a boom. Pattern glare?

Hopefully will get there

Prompt treatment makes Al the difference

Rocky profile image
Rocky in reply to Nackapan

I did see 4 other A and E Doctor's too on that day, but was very lucky to have got the one that knew about B12, the others didn't know what they were talking about, or understood the neurological damage we can suffer. I wish you well with your recovery

Nackapan profile image
Nackapan in reply to Rocky

Goodness 4! they must've been puzzled. Yes at least yiu saw the one with the knowledge abd gif promot treatment 👍I wrote to PAls after once I knew I was deficient for their awareness, / training.

Reply took it as a complaint which actually it wasn't . Hey ho

Rocky profile image
Rocky in reply to Nackapan

I know they don't like it when we try to suggest they have training which I also suggested to my surgery. I have been on b12 injections for pernicious anemia since 2012 and my GP kept ignoring my symptoms and refused to increase me from 8 weeks. I only got listened to after being in A and E and the Doctor there writing to my GP to say I needed 4 weekly injections

Nackapan profile image
Nackapan in reply to Rocky

Mine only eventually put me back on loading after a neurologist wrote to them!! Lots of gps disagreeing in the same practice. But no other diagnosis !

Nackapan profile image
Nackapan in reply to Rocky

Interesting . I had 2 brain mris too at later dates. Reassuring not alone, but my goodness.

I wonder why pupils dilated.

To date never explained.

Om still light sensitive dk sti going on I expect.

Sedn 3 levtjs if optometry. Eyes healthy.

So must be signaling/ nerves

I'm 3 yesrs on now.

After trying a few frequencies am prescribed 2 weekly

Last yesr bought my own supplies too.

Got concernex about access to thr surgery.

After buying my own the Gp turned round the decision not to allow me to inject sc at hone.

A battle and long story

I wish yih well.

If you are jittery it sounds like your magnesium is low.

Curious about your iron levels - get them to monitor those closely.

While they are testing for that get them to test for



folate (happens automatically with B12 here)

Vitamin D

You will need all these for your extra B12 to work optimally and may easily become deficient if they are used faster than normal.

Unless you are already under weight don't worry too much about the lack of appetite, it can be that you were instinctively craving food to try to get the nutrients/B12 you needed and now you have them/it in plentiful supply your body is feeling satisfied.

Once all yours levels are good and stable you will feel better.

Yes my main symptoms are jitters. I feel anxious which I didn’t before b12. And very aware of my heart/ palpitations. All since the loading dose. I went back to gp only a telephone call and asked if I could have a blood test to check what else is going on as feel odd. Told me o couldn’t have till two months after the loading dose and got to wait.

Just don’t like the feeling of the palpitations.

Thank you for the reply.

Sallyannl profile image
Sallyannl in reply to Moobear2

Try eating banana s , good for potassium and magnesium. I swear by them and always eat one before injection.It's horrible feeling and I ended up in hospital, it will subside. Best wishes

Moobear2 profile image
Moobear2 in reply to Sallyannl

Funny you should say that as I have a banana and orange juice for breakfast and my symptoms seem better for a few hours afterwards. Thank you

Sallyannl profile image
Sallyannl in reply to Moobear2


Nuts are good too if you aren't allergic to them. Try looking up "sources of...." online to see what you will like.

Food is much more magical than anyone gives it credit for!

Dark chocolate too !

Moobear2 profile image
Moobear2 in reply to Sallyannl

Thank you 😊

Thank you 😊

Kaheena100 profile image
Kaheena100 in reply to Moobear2

Try taking a few nuts or seeds with your banana for a little good oil and protein 💐

Moobear2 profile image
Moobear2 in reply to Kaheena100

Thank you 😊

This is an extract from the link in Villiangiriblues post of today.

Some patients respond so well to B-12 that they become hyperactive-nervous and excitable-but this too can usually be resolved by reducing the dose. Because of this excitatory effect, I recommend that B-12 be administered in the morning, so that it will not interfere with sleep

Nackapan profile image
Nackapan in reply to Budsa

Yes its always a mistake fir ne if injected afternoon or evening. I do it as early as possible.

Thank you all for the reply’s. I’ve had no advice of my gp other than get on with it.

Nice to know others are going through similar things.

Makes me worry less 😊

I had my last loading dose on 2 October. So far, the positives outweigh the negatives.On the positive side I feel less tired, I do get occasional palpitations but these are rare.

The nurse who administered my final dose noticed that I was 70 years old and had not had my shingles jab whereupon she gave me my shot there and then. Hats off to her for being proactive. I gather from older friends that one used to be called in for the shingles shot at age 70 but this practice seems to have lapsed.

That’s good you feel better. Mine are not as bad as the first week after loading dose.

I felt like I was having a heart attack and im


Im moving into my 4th week now.

Symptoms definitely eased but wasn’t expecting to feel that way I felt after the loading dose.

Lauren355 profile image
Lauren355 in reply to Moobear2


Am feeling very similar to you, have just had my 10th loading dose and don’t feel great. Have had palpitations and dizziness (amongst other symptoms) since my 7th dose, also heightened anxiety which I’ve never suffered with before! It’s awful isn’t it?!

Was scared I was having a heart attack too and am 35!

My gp is going to do a ecg and also mentioned running some urgent blood tests just to check everything, am not due my my b12 blood test until December but would rather get one early to see!

Hope you feel better soon :)

Moobear2 profile image
Moobear2 in reply to Lauren355

It’s the worst isn’t it. Im suppose to be in work. Never take time off. But with the palpitations and anxiety can’t cope with going in.

I’ve not suffered with either before the b12 loading dose.

It’s put me off having anymore as feel like it hasn’t agreed with me.

Glad your gp is helping. Mine said I can’t have bloods until two months after loading dose.

Let me know what they say.

Hope you feel better soon too 😊

Lauren355 profile image
Lauren355 in reply to Moobear2

Me too, was working from home and now just been signed off for a couple of weeks as can’t concentrate etc!

I’m not having anymore until December now apparently and that’s when gp wanted to check my b12. I’ve complained for the last few weeks though as feeling worse I think that’s why they said they will have another look- will let you know!

I’ve heard it can sometimes get worse before it gets better so 🤞🏻We get there soon!

Moobear2 profile image
Moobear2 in reply to Lauren355

It is hard to concentrate isn’t it and Hard not to think about it. Hope you get some answers.

Hopefully 🙏

Unlike you I have taken drugs - years ago in my Uni days. I too had the symptoms you described. It is the same effect as when you take amphetamines. Amphetamines are stimulants. One of the side effects is elevated heart rate and blood pressure and they also can cause dilated pupils. Which is why one doctor asked if you were on drugs. Personally I liked the effect. I felt energised and content and was upset when it went away. Based on my experience with amphetamines I think you will find that your jitters are extra energy that you are probably not used to experiencing and will subside if you use that engergy i .e go for a walk or give the house a good clean. A lot of people on this forum also got a similar effect with loading doses. I don't know why it happens but I believe it is a good sign that the B12 is restoring energy levels in the body. It will go away once your body acclimatises.

Moobear2 profile image
Moobear2 in reply to charks

Oh wow really. Yes it’s not a feeling that i like the feeling off. I’ve literally sat on sofa since I felt like this as thought my heart had problems so maybe ive made it worse.

I stopped going into work.

Maybe like you said I should use that energy up.

Better get the hoover out.

Thanks 😊

This happened to me and I told my GP to give me one injection weekly which he agreed to instead of the 6 in 2 weeks and that solved the problem. I carried on with one injection per week for 3-4 months and things really improved.

I started self injecting after that every 2 weeks as my GP retired and new GP refused injections as it happens with a lot of us on this forum…..common problem.

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