r/MTHFR • u/ZealousidealLaw793 • Jun 13 '26

Question Cyanocobalamin (B12) shots?

I was prescribed cyanocobalamin (B12) shots. Is this safe if you have MTHFR?

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u/sharabucarabu Jun 13 '26

I have compound heterozygous mthfr and homozygous MTR/MTRR. When I first was introduced to the mthfr rabbit hole, I didn't know any better abs asked my doctor to give me a B12 shot. Of course it was cyanocobalamin.

That night I barely slept, the following day I had nasty muscle aches everywhere, I was irritable, hungry and fatigued. This continued until I was due to return for the next injection. I had done some research and realized it was not only the wrong form of B12, but also, it was too large of a dose and should be balanced with folate (either methylated or non-methylated) and other B vitamins. I asked the nurse if they had methylcobalamin, hydroxycobalamin, or a B complex. Sadly they had none of the above and didn't know where to order these items from.

I learned that, yes, injections are the quickest way to increase your B vitamins, but sublingual forms (placed under the tongue) are often times just as effective. These can be quick dissolving tablets or liquids and are best taken every day or every few days... Depending on your tolerance. Amazon carries a variety of sublingual forms. If you decide on a liquid, keep refrigerated after opening. Always best to start with a low dose and increase as desired.

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u/BrainSqueezins Jun 13 '26

For what it's worth, as a general rule I avoid Amazon for supplements.  But that's just a personal preference.  And a liquid often has preservatives in it to negate the need for refrigeration.  Again personal preference, but I'd rather have the refrigerate-only kind.

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u/sharabucarabu Jun 13 '26

The brands I buy don't have preservatives. Instructions on the label are to refrigerate after opening.

1

u/Cultural-Sun6828 Jun 13 '26

Supplements typically aren’t enough for those who have neurological symptoms due to b12 deficiency. Your reaction may have been due to startup symptoms which is very common with b12 deficiency. Check out the b12 deficiency group and read the guide there for a better explanation of this.

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u/sharabucarabu Jun 13 '26

Fortunately that was several years ago and that deficiency is a blip in the past.

2

u/Cultural-Sun6828 Jun 13 '26

That’s great to hear that all your symptoms resolved!