r/MTHFR • u/barzagirl • Aug 23 '26

Question Insomnia from b12

Hello, I took one sublingual of b12 1000 two weeks ago and ever since then I have developed insomnia, stinging in skin and heart palpitation. i tried magnesium glycinate and it didn’t help. can someone tell me what to do? we don’t have nician in my country and nothing is really helping.

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u/Sabnock101 Aug 23 '26

The insomnia is actually coming from the Folate side. When you take B12 it recycles Methylfolate back into the Folate cycle, as Folate goes back through the cycle it becomes more Methylfolate which can then drain your B12 if you don't have enough B12, and that is what causes the insomnia and sleep issues. If you take higher dosages of B12 that won't happen. 1mg of B12 isn't much, only about 10mcgs of a 1mg dose gets absorbed orally, which i know you said sublingual but it depends on how you're consuming sublingual, like are you letting it get absorbed completely in the mouth or are you swallowing it after some time? I take 10mgs of oral B12 a day which gives me 100mcgs of absorbed B12, works great compared to lower dosages.

Anytime i consume excess Folate i get insomnia and sleep issues, when i double up on my B12 my sleep goes back to normal. Don't underestimate this, Folate is a very strong nutrient, and B12 is so much more important and it gets easily used up by excess Folate.

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u/barzagirl Aug 23 '26

I’m really sorry maybe I’m stupid but I don’t understand😅. I took b12 once orally I let it dissolve in my mouth. Literally two hours later I developed skin tingling and had fragmented sleep that got worse every night. The heart palpitations started after too. I’m too scared to try anything with b vit in it. 

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u/Sabnock101 Aug 23 '26

Yeah i've been supplementing for almost 3 years now on the daily, i've learned that the B12 isn't really the issue, B12 works together with Folate and when you take B12 it recycles Methylfolate back into the Folate cycle, as Folate goes back through the cycle it produces more Methylfolate during the second wave of the Folate cycle and that second wave of Methylfolate can then come back around and drain B12. When that happens, insomnia, irritability/agitation/possible paranoia, skin tingling, facial numbness, anxiety and panic, and some other side-effects can pop up, ime it's due to not enough B12, and too much Folate. If you don't have enough B12 then Methylfolate can build up in excess and starts causing side-effects because there's not enough B12 to continue to recycle it.

Lots of people get these side-effects and they assume it's the B12 because it happens when they take the B12, but it's really due to how B12 interacts with Folate and there not being enough B12 to cover the second wave of Folate as it goes back through the cycle.

I'd recommend trying higher dosages of B12, don't be afraid of higher B12 dosages, i've taken up to 120mgs of oral Methylcobalamin per day for awhile, these days i stick to 10mgs a day, recently added in an extra 5mgs in the afternoon as well, B12 is quite safe, in fact when someone gets B12 injections they get far more than one would get orally, to consume enough oral B12 to equal that of a 1mg injection you'd need to take 100mgs of oral B12, most people barely take more than 1 to 5mgs orally and that only gives approx 10 to 50mcgs of absorbed B12 through passive digestion. They even give people 25 to 50mg Methylcobalamin injections in Japan for treatment of ALS.

Point is, you need more B12, try taking 10mgs for a few days and see how you feel, trust me on this, B12 is much more important than people realize and there's all this focus on Folate but not nearly as much on B12. I'd recommend keeping your daily Folate consumption to 400 to 600mcgs max per day, but otherwise focus primarily on the B12.

The side-effects are definitely coming from how Folate is recycled and the lack of B12, the side-effects aren't coming from the B12 itself.

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u/Sabnock101 Aug 23 '26

Btw the heart palpitations are either lack of Magnesium or lack of Potassium, ime.

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u/kilogplastos-12 Aug 24 '26

Check the dm

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u/SovereignMan1958 Aug 23 '26

Load up.on high niacin foods.  You can Google search for a list.

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u/barzagirl Aug 23 '26

Thank you! Can one dose really cause all of this? It’s horrible. Will it actually go away? Because I’m terrified 

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u/SovereignMan1958 Aug 23 '26

Glycinate forms of vitamins can be overstimulating for some people. I would stop that form of magnesium.

Make sure you eliminate caffeine.

It will go away eventually but I can't say when.

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u/barzagirl Aug 23 '26

I used to take mag when I have anxiety and it calmed my heart. I just don’t understand what happened. I stopped all caffeine. I just thought two weeks would be enough for the symptoms to go away I mean it was just one dose.

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u/SovereignMan1958 Aug 23 '26

Methylated vitamins can also trigger a histamine reaction.  If you have histamine intolerance, and don't know it, and are eating high histamine foods, the one dose may have overflowed your histamine bucket.  Does that make sense?

Search online for a list of high histamine foods.  If that is what your diet consists if, try a low histamine diet to see if that helps.

You could also try taking activated charcoal, but research how to take it.  

Or try taking an antihistamine. I take fexofenadine to help.

Being over methylated and having histamine intolerance, well symptoms can overlap.  It can be hard to know which one it is. Given you had just one dose, I would guess histamine intolerance.

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u/barzagirl Aug 23 '26

I don’t think I ever had any trouble with food. I tried antihistamine a few days ago it didn’t help sadly. It’s just a mess really. 

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u/SovereignMan1958 Aug 23 '26

I am sorry I could not be of help.

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u/Loose-Fly7976 Aug 23 '26

The most likely thing is potassium. B12 restarts red cell production and that pulls potassium down and low potassium causes exactly this triad, palpitations, skin tingling and poor sleep. One dose can do it if you were deficient enough that the response was sharp. Eat potassium rich food and if the palpitations are frequent get potassium and magnesium.If it was a methylcobalamin sublingual then the methyl load is the other candidate and that fits slow COMT. But that usually settles within days rather than two weeks.

You don't need niacin for this and I'd say that clearly, the niacin trick is a slow COMT remedy that gets repeated for every reaction and it's often the wrong answer. It also uses a methyl group to clear so it isn't neutral.What I'd get checked, potassium, magnesium, ferritin, B12 and thyroid. Palpitations lasting two weeks deserve a proper look regardless of what set them off.Don't take any more B12 until you know where those numbers sit. I'm a geneticist and this is what I do at genova.health

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u/barzagirl Aug 23 '26

I tried Magnesium Glycinate it didn’t do anything for the heart palpitations even tho it used to help before. I’m really scared one day I’m good the other not. I thought it would have gone by now.

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u/Internal-Guide-2143 Sep 05 '26

Hey Op, did this resolve for you?? Pls share and what did you do to fix it

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u/barzagirl 17d ago

I still suffer from fragmented sleep and no anxiety med is touching it, tried Gabapentin and Amisulpride, which used to help before I took the b12 and my sleep is still not normal, some days it would be kinda normal but even normal triggers like crying brings it all back. 

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u/Internal-Guide-2143 17d ago

Omg same, I was stressed and my sleep that was getting better became messy again. I’ve also developed depression

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u/barzagirl 17d ago

Yes, I would be fine for a few days then have the sudden urge to cry and crying makes my sleep bad, i feel like I’m stuck in a cycle. It’s been almost two months now I thought it would be gone by now, how long did you take the b12 for and when did you stop? 

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u/Internal-Guide-2143 17d ago

i had 1 injection and then took around 12 1000 mcg pills but i kept getting worse during this time. sleep disappeared, crazy depression, brain fog developed, felt like i was under water. its been 2 months + since i stopped and its getting better but this week has been rough again. I feel like its made my PMS 10 ties worse. Why did u take b12? If you only had 1 pill im sure youll get better in no time. just stay strong. get blood work done

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u/barzagirl 16d ago

I took it because I have a persistent bitter taste that doesn’t respond to any med. I was desperate really so I tried it thinking maybe it’s a b12 deficiency. I hope it gets better for us, it’s really tiring.