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Pernicious Anaemia Society
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How long until muscle twitches resolve?

Hi, I'm newly diagnosed with low B12 (my result is 147, normal range 181-914). I have not been diagnosed with pernicious anemia, at least not yet--the cause of the low B12 remains to be found. I was tested because of tingling in my arms and legs and muscle twitches in my legs. I had 7 daily injections and have had one of 4 weekly injections. The tingling seems to have improved, but the twitches have not. They are small, brief and almost constant, and I now realize they are all over my body, not just in my legs. They're not painful. No one can see them, and when I'm active I don't really notice them. From what I've read, it may take some time for them to go away, or they may not go away at all. I'm just curious to know about others' experiences with muscle twitches, and whether they went away, how long it took, etc. I would also like to know how it can be determined that the twitches are related to B12 deficiency, and not another cause? I'm living in fear that the B12 diagnosis is a red herring and something more serious is going on, but I don't want to embark on an unnecessary round of visits with specialists and testing. I should also mention that my vitamin D is low, so I am taking vitamin D. Magnesium was normal at the time my B12 was tested. I would greatly appreciate input from others with similar experiences.

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you will have low iron levels too . Try taking a spoonfull of blackstrap molasses each day to bring your iron levels up too .


Beware of he woo-woo.

A teaspoon of blackcrap molasses contains less than half a mg of iron. It is useless, expensive gunk.


sorry but I don't think there is an answer to your question - people vary a lot when it comes to B12 and what is true for one person may not be true for another. Nerve damage heals very slowly and, unfortunately, if you were deficient for some time before you started treatment, some symptoms may be permanent.

However, having said that you are only a month into treatment - so it is still quite early days. Many people don't really notice much for months. Make sure that you have a full list of your symptoms and try to focus on what is improving.


I used to always get muscle twitches in my legs before starting B12. This happened especially after exercise. This increased initially when I started B12 and rather scarily started in my hands. It took almost 2 months for this to fully resolve from starting B12.

I now very rarely get muscle twitches at all.

It is difficult to say if B12 is the cause. My obsession with B12 means that I probably over attribute. It did cross my mind that I was developing something awful like Parkinson's disease but thankfully not.

I think sticking with B12 and keeping a symptom diary to try to establish what was getting worse or better and the overall trend was most useful in my case.

It is important to keep an open mind though and there have been a couple of posts here recently where people have reported thinking some symptoms were B12 deficiency related and they turned out to be caused by something else.

I know many people have had difficulty with GPs (including me) but keeping GP in the loop if symptoms don't improve with B12 may be a good idea.

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Thank you. I think your suggestion of a symptom diary is very helpful. I will start one right away. Thankfully, I feel like I have a very good doctor who is my ally and who respects my input. It also helps to hear that there is hope that some of these symptoms may yet resolve. I will try to be patient and not imagine other, scarier scenarios. Thank you for responding.

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I found muscle twitching could be caused by low potassium. B12 treatment can deplete potassium apparently.

The recommended dietary allowance of potassium is 4700mg per day. I found that just taking 2 x 99mg potassium tablets was enough to get rid of my twitching. More is not better with potassium. Anyone taking it as a supplement should keep their dosage to an absolute minimum.

Another nutrient which can cause twitching and muscle spasm if it is deficient is magnesium.


If the signs and symptoms described in the above link seem to fit your symptoms then you might want to consider a magnesium supplement. I take 300mg magnesium citrate per day, just before going to bed. (It can make people sleepy). There are loads of other magnesium supplements around :





Thank you. I've been eating a banana each day to help with potassium, and I do think it helps, but the twitches continue. I will talk with my doctor about a potassium supplement. My magnesium was normal at the time may B12 was tested, but if I understand correctly, the B12 treatment may lower my magnesium, so I will try to get a supplement. Thank you for responding.


B12 treatment does not lower magnesium (or potassium unless beginning treatment and in case of anaemia) but many patients with PA have low magnesium (because of gastritis). The thing is that blood values of magnesium are not very reliable. Muscle twitching can be low magnesium, so that's certainly worth trying. Potassium as well, but take only in supps after talking with your dr so it can be tested and monitored; but adding it more in your diet (more than one banana) won't hurt.


Thank you very much for that clarification! I will look for dietary sources of potassium and take a magnesium supplement. I will also talk with my doctor about potassium supplements.

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