Log in
Pernicious Anaemia Society
16,697 members β€’ 11,563 posts

Potassium and B12 injections

I have recently discovered I have a B12 deficiency and so I have been doing some research. I have heard people saying that the B12 injections caused them to have painful muscle spasms and this was seen as being an unwanted side effect of the injection. I have found that when you have the injections your blood cells start to repair rapidly. This process requires large amounts of potassium and when that potassium runs out you can get muscle pain and spasms. I just wanted to pass this on so that anyone experiencing this knows it is a sign you are getting better but need more potassium.

31 Replies
oldest β€’ newest

Peanuts with the skins on are good, i'll post again if i find any more info, good luck.xx

I would be grateful for any tips on self injecting as I havent a clue how to go about it. x


That is really helpful, thanks. I look forward to seeing the video.


Ideally you will get all the potassium you need from your diet but if you need more you can get it from LoSalt, available from some independent stores. This is 66% potassium chloride and 34 % sodium chloride.

In the USA you can get NoSalt.


Denise I use this too, have done for quite a while, it now seems to be available in a lot of the supermarkets, we used get it in M*rrisons when we lived in the south and buy it in T*sco here in the midlands, it is kept with all the other salts.



Thank you!

I hadn't thought about Morrisons. Our Tesco's only sell Saxa which isn't as good. Our Co-op's used to sell it until I started using it and then they stopped - typical!! 😁

1 like

I bought 350 g of 'Reduced Sodium Salt' for a quid in Sainsbury's. Same recipe as LoSalt.

Damn. I should have shopped around - only 90p in Tesco.


I havent researched/looked to buy B12 injections yet. Still trying to get my NHS doctor to help. But I feel this may be futile and I dont have the energy!

Thanks for the advice,

1 like

Hi Alison-Thomas. Just thought I'd let you know that taking too much potassium can be dangerous (as can low levels) so please take care and avoid simply adding potassium in tablet form, as this may cause problems.

As Deniseinmilden points out, potassium is best obtained from diet. If you suspect you're not getting enough from diet, then it's always best to ask a GP to check your potassium levels. My understanding is that this should be done routinely, especially if you're on B12 in high doses, but most GP's don't know this and don't do it. So it's worth asking, if you are concerned.

It's also worth saying that there many other vitamins and minerals (called co-factors) that are involved with the uptake and utilisation of B12 (i.e. Folate, magnesium, vitamin D etc) and taking large doses of B12 can also deplete iron. These (and others) are all important to the recovery process, so it's important to get the balance right. But this is not always an easy task!

Being too low (or too high) in any of the co-factors can make you feel very unwell - I'm still working to get this right, so I know how difficult it can be!

Many here recommend taking a good multi-vitamin and mineral tablet daily.

I expect you've already been reading about this, but if you want more information, there's lots on this site - just do a search for 'co-factors' and lots will pop up.

Good luck πŸ˜€


Thanks for the advice, I will now be aware of the co-factors issue. During my research I have found many people unaware of this and assume B12 isnt working because they feel worse.


Yes, know what you mean. I was one of those people until I came here!

Good luck πŸ˜€πŸ˜€


As foggyme

1 like

Thank you for this information, this has happened to me, not on a large scale. Comforting to know. We are healing.


Can anyone explain to me the link between B12 injections and the muscle spasms and muscle stiffness I am experiencing? I eat a daily banana for added potassium . I cannot believe how stiff my muscles have become over the last year even though I have been supple all my life and exercise regularly. It can't all be down to age as the onset has been so rapid . I have 8weekly injections and I feel these are sufficient. Just.



Hi Doityourself. I too have increasing joint stiffness and muscle spasms but I'm not sure that this is linked to the actual B12 injections. Like you, I have, prior to B12 deficiency, been fit and active.

But....I remained undiagnosed for quite some time and on diagnosis was undertreated for the first four years.

I have read somewhere (sorry, but just can't pull out of my brain where that was) that insufficient treatment for B12 deficiency can result in the eventual onset of stiffness and muscle spasms. For me, this was an ah ha moment: I think my stiffness may be related to undertreatment with B12 injections in the early stages of deficiency. (Reference reading was either in Patcholok, Hooper, or on the b12deficiency.info website - if I remember where, or I find it again, I'll PM you the details).

Now self injecting with B12 but only time will tell whether lack of B12 is the cause or if it's possible to reverse this nasty symptom.

But this is only me.

Stifness and muscle pain can have other causes so it might be something that's worth discussing with your GP, especially if they're getting worse.

But I do wonder...when you say 'just' getting enough B12 on the eight weekly regime...are you sure?

I thought I was but it appears I was having enough to keep me alive - just - but not enough for my body to heal, hence it was slowly getting worse (the stiffness and other symptoms dodging in).

Could it be that you need more B12, so that your body can heal properly? Just a thought πŸ˜€.

If you think that's the case, I have to say that unless you're very lucky in having a GP who knows something about B12 deficiency, you may have to think about adding the extra yourself (sublinguals, patches, drops or self-injecting). Lots of people here to help if that's the route you decide to take.

Hope you find a solution...know how horrid it is to feel like a 100 year old...on a good day!


ThAnks that was helpful,you described me exactly. I was undiagnosed for many many years and count was 72 before I was diagnosed. Then injections only every 12 weeks. I managed to get 6 weekly by travelling to Germany and receiving treatment there but only able to get 8 weekly here now. If you find reference let me know, would be very grateful. English gps attitude to p.a is hideous. In Germany they asked me how often I thought I needed injections!

Hope you feeling well atm.


Thanks for sharing this. I am currently not being believed by my doctor and feel dreadful. I dont know what to do in order to be believed. Currently looking into private treatment.

1 like

Hope you find some thing. Let us all know how you get on, maybe useful to others.


Oh dear Alison-Thomas...I know just what you mean about not being believed...as do most people here, so you're not alone in that!

I've also tried the private route, but with little luck! In fact it felt worse, as I simply paid a lot of money to be told 'B12 is for people in wheelchairs...and you walked in here unaided!' Unbelievable!

But some people do manage to find consultants who are knowledgeable in all things B12, so I really hope that you manage to become one of them.

Also - you're doing the right thing by seeking to become your own expert. Being here and doing lots of learning has helped me to realise that is is not me, I'm not mad, its my body that is bad!

B12 deficiency is a tough road to follow but please don't lose heart, keep at it, and post away anytime you need some help or a little perk.

Very best wishes and good luck πŸ˜€


Hi Doityourself. Heartily agree with you about the attitude of English GP's to PA! It really does beggar belief!

Been looking for that reference...but it's still managing to escape me! I know I have it somewhere...it will pop up eventually. When it does, I'll PM you the details...made a note so I can't forget.

Take care xx

1 like

Hi Foggyme,

Like you and doityourself, I am experiencing increasing muscle pain and stiffness after almost a year after diagnosis of PA and monthly jabs.

My B12 was 134 at diagnosis. I was given four weekly loading doses before I was supposed to go to monthly jabs, but while waiting for that first monthly jab, I went downhill so fast that I went back to weekly jabs for a few more weeks.

You mention that under-treatment in the early stages of treatment may be the cause of the pain and stiffness and I was wondering if you'd increased your treatment to counteract that. Are you doing weekly jabs? If so, has it helped? I self inject and despite my doctor saying my pain and stiffness is not B12 related (?!) I'm thinking about going back to weekly jabs again to see if it helps.

My pain is at its worst two or three days following a jab. I was unaware that potassium levels could be affected by high doses of B12, and that that might be a factor too. Argh! No matter how much I read up on this, I always have more to learn.

Aside from the pain and stiffness another big symptom for me is what I've come to think of as 'missing words'. I'm usually OK writing, but I have trouble remembering even simple words and concepts when in conversation.

Anyhow... any insight from your experience (or anyone else's) would be greatly appreciated. Thanks!

1 like

Hi Sweetmaddie. Really sorry that you're struggling...it's awful what this nasty little thing does to us, isn't it!

There have been several,posts recently from people struggling in the same way and B12 deficiency / PA is so complex that it's quite difficult to sort out what's going on!

Yes, I did increase the frequency of injections, up to every other day because of the neurological symptoms, and whilst this has effected minor improvements, the major symptoms are still present (muscle stiffness, pain, weakness, etc.). Been doing this for three months now.

I've been working on co-factors and as far as I am able to tell, the only one that's low now is serum ferritin and serum iron (supplementing for these, so that's not the problem).

Following replies from others here (I.e. Gambit62 and ndodge ), I'm now going to try altering the B12 regime to smaller doses, injected more frequently (this apparently works for some people with functional B12 deficiency - others do better or really high doses - but it's really difficult to know what is going to suit you, without trying!).

If this doesn't bring improvements, I'll then try nasal drops (Gambit62 - who had similar problems - recently wrote in a post that she didn't start to improve until she started using the nose drops). Just goes to show, different things work for different people.

I found the reference to stiffness and muscle pain in undertreated B12 deficiency....it's in the pinned posts to the right on the home screen (sorry, foggy so can't remember precisely which one - but it's there if you want to have a search). It's related to something called Subacute Combined Spinal Cord Compression. This is a later complication of under treated B12 deficiency and something that not many GP's will be aware of. It's likely to be accompanied by other neurological deficits though, and it's worth remembering that muscle stiffness and pain can be caused by many other things.

Interestingly, I've just had a positive antinuclear antibodies (ANA) blood test result, so it looks like something autoimmune may be going on. My GP has (eventually) referred me to both a rheumatologist and an endocrinologist for further investigations, so perhaps that will throw some light on the matter.

I've also recently had a head and spine MRI and am awaiting the results of those.

I note that your GP says that the stiffness etc. Is not related the B12 deficiency? Well, all I can say to that is...how does he know? It's is a recognised symptom! Also, has he offered another medical explanation? Is he undertaking further tests? Have you been referred to a rheumatologist?

I also note what you say about finding words....I also get that (lovely, isn't it!). This is a neurological symptom...do you get any other neuro symptoms (i.e pins and needles, numbness, balance problems, ringing in the ears etc.). If so, your GP should refer you to a neurologist for further investigations (at least to rule out any other conditions).

Your B12 level at diagnosis (as far as I can tell without the reference ranges) looks very low.

Not sure if you know this but it's worth mentioning that if you have any neurological symptoms when you were diagnosed, the B12 regime (according to all guidelines) is six loading doses of 1mg B12 and then 1mg injections every other day until no further improvement (for some people this takes many months). Your GP may not know this! The information about this regime can be found is something called the British National Formulary (BNF), the doctors' prescribing 'bible'. Your GP will have a copy on his desk. He would have to read further than normal to find it - it's the second item down!

If you didn't have this regime and as you do appear to have neurological symptoms, it might be worth going back and asking him to put you on this Evie. Might also be worth going armed with evidence and guidelines, since many GP's do not know about this and are often reluctant to offer it to sufferers (I know mine was).

Oop...and while I remember...potassium...it can be dangerous to take too much potassium so please try and get this from potassium rich food, rather than supplements. Certainly, if you think you need to supplement, then this should be monitored by your GP (he should be checking potassium levels anyway, since you are having B12 injections). Sorry...been here a while and have to go but you can find info on potassium rich foods on the Internet...some also us lo-salt.

Hope you manage to find something that works for you and improves your health, very soon.

When I have more answers from various appointments and tests, and if I discover any more information that might be useful, I'll post an update.

Good luck and take very good care x


The idea of loading shots is to get lots of B12 in to your system very quickly so healing can start from there.

How long it takes for specific symptoms to dissipate will depend on what exactly is causing those symptoms. B12 is used by a lot of systems in the body which includes the nervous system and the system that creates healthy blood cells. It is also used by the processes that release energy in your muscles. Muscles will respond quickly but the nerves and replacement of deformed blood cells with healthy ones will be much slower.

Many people experience greater problems with pain etc when they start supplementing - signals suddenly start coming through much stronger and it takes the brain a little while to recover.

B12 is also used by the immune system - so not having enough leads to higher rates of infection but also means that some of the responses that we associate with being unwell (which are actually the immune system fighting the infection) - like runny nose, rashes - can also seem to go into overdrive for a while.

as Foggyme says potassium is something that needs to be closely monitored if you have significant anaemia but isn't something I would recommend supplementing without medical supervision. If your levels are or might be low your GP needs to know about this. It is a particular factor during the early phases of treatment and mentioned as something to monitor in cases of severe anaemia in NICE guidelines.


Thank you Foggyme and Gambit62 for your very thorough and thoughtful replies. I'm in the US and seems the loading dose protocol here is unfortunately less aggressive. I self inject and am comfortable adjusting my dosing frequency if I choose to do so. I need to read up on Gambit 62 and ndodge's smaller dose/more frequent experiences as well as the nasal B12. Both good possibilities for me to try.

I feel I've gotten as far with my GP as I can but I've found some thoughtful support from a nurse practitioner in another office and through her I've gotten a referral to a rheumatologist who I will see at the end of September. She's also referred me to an infectious disease specialist, which may sound a little out of the norm, but I've been living in the Caribbean for most of the past five years so ruling out the possibility of parasites (some of which can severely deplete a body's B12) is a worthwhile step for me.

I haven't had an ANA done, which I will discuss with the rheumatologist. Maddeningly, my insurance company denied my GP's request for a head/neck MRI. I'll be interested to know what you find out from your MRIs.

I'm cautious about supplementing and am bumping up my potassium only through food. I'm a really healthy eater but in addition to my monthly B12 jabs I take a daily B complex. I just added in a balanced magnesium/calcium/zinc supplement and will give it a month or two (or three?) and see if I notice anything good/bad.

My B12 test last month (after a year of treatment) was 590. Oddly, when I had it checked in January it was higher, about 700. Is it expected for the level to fluctuate when the treatment is steady? I suppose my body uses more or less at different times. Must read up on that too. So much to learn.

Thank you both....

1 like

Hi Sweetmaddie. Sounds like you're really getting a handle on all this πŸ˜€. The nurse practitioner sounds excellent!

Parasites....now that sounds interesting....but not as interesting as living in the Caribbean for five years. How marvellous.

And yes, you're right about the B12 levels fluctuating....depends on where you are in the injection cycle, how much exercise / activity you have been doing, infection, medication, stress....and a whole host of other things.

Good luck with the referrals...hope they turn up something that will help.

Will let you know MRI results, when I get them.

Take very good care xx


I was finally correctly diagnosed with Pernicious Anemia in 1994. I had been going to Dr.'s a long time getting sicker and sicker and they kept missing it. By the time I was diagnosed I was in full blown Megaloblastic Anemia, all my levels were so low the Dr. told me I was within weeks of expiring! It took a long time to come back and the nerve damage had already been done. I give myself the injections IM. I have not had a problem with potassium issues and I get a yearly physical with very through blood work. My mother had P.A. I didn't know it was genetic, but apparently it is. I got tired of sticking a needle in my thighs and I tried the B12 nasal gel (RX) but it was like shooting jello up your nose, so I went back to the needle. So if anyone is thinking of the nasal gel, you might really want to rethink that one. I do have muscle & joint pain but that is from Fibromyalgia. I agree with the others about too much potassium, just be careful. I'm so glad I found this site. When I was diagnosed there was virtually no info out there. Good Luck to everyone dealing with this.


A potassium tip is coconut water. A 250ml glass contains 20-25% RDA of potassium (regular B12 injections may require a little more). I found adding in a couple of glasses of coconut water a day easier to manage than 2-3 extra bananas.


Brilliant tip Booksellercate....many thanks.....I love coconut water πŸ˜†πŸ˜†


Many thanks for all replies. I am in England and I think I will just diagnose and treat myself from now on. I simply dont have the energy to waste fighting a battle that I know i will never win. The NHS doctors are not in the business of diagnosing and curing people. They just treat symptoms by prescribing medication, sales men for drug companies. They dont care what the cause is. Thanks to forums like this we can support each other on our journey.

Best Wishes and good luck all xx


So how would you make sure you get enough potassium, are there any supplements that one can take to ensure adequate potassium intake ?


The best way is a balanced diet.

Unless you are recovering from macrocytic anaemia (or you've recently lost a lot of weight) you shouldn't need extra potassium.

1 like

Hi camillahealth.

I agree with fbirder...the best way to get enough potassium is through eating foods that are rich in potassium (bananas for one - lots of ideas on the internet too).

Potassium is very finely balanced in the body and too much can be as bad as too little (over supplementation can cause cardiac arrhythmia and heart attack)... so taking potassium supplements should only be done under direct medical supervision.

If you're worried about your potassium levels, you could always ask your GP to check your levels and take it from there.



You may also like...