Update: B12 shots have recently become unavailable online due to regulations. Until now. I partnered up with Oxford Biosciences to give you the best vitamin B12 supplement.
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Vitamin B12 is great. It helps form red blood cells. It is crucial to the synthesis and repair of DNA and the myelin sheath, a layer safeguarding our nerves. It also aids optimizing our homocysteine levels, decreasing our risk of blood clotting and heart attack. But can we actually have too much B12?
That’s what this post is about.
Can too much vitamin B12 hurt you? Can it not? Is vitamin B12 toxicity a scary possibility, or can we just continue injecting ourselves with huge doses with no mercy? Here’s everything you need to know about vitamin B12 overdose.
Vitamin B12 Overdose Symptoms & Side Effects
Can you take too much B12?
Short answer: No.
Certain vitamins can harm you when taken in excess, specifically fat-soluble vitamins like A and K which will build up in your fat stores. Vitamin B12, however, is water soluble and will be flushed out in your urine if taken in excess. Therefore, there are no vitamin B12 overdose symptoms.
The recommended daily dose is very low, about 2-3µg, yet many supplements deliver hundreds or thousands of µg per dose. This is no mistake. There’s a reason no upper limit for B12 has been set by The Food and Nutrition Board.
Consider this:
B12 (the methylcobalamin form) has been used in ultra-high doses (25 to 50 thousands of µg doses!) to prolong survival of ALS patients and aid patients with peripheral neuropathy and chronic axonal degeneration. It is also used in huge amounts to detoxify cyanide poisonings.
We’re talking here about 25,000 or 50,000µg doses. That’s more than 10,000 times higher than the recommended daily limit, yet it still causes no excess vitamin B12 toxicity symptoms.
Summary: Can You Have Too Much B12?
Can you overdose on B12?
No.
No matter if you inject yourself or consume a ton of vitamin B12 foods every day, any vitamin B12 excess will be excreted in your urine. My point?
Don’t worry, and enjoy the benefits of B12.
This article is part of a larger guide: Vitamin B12.
Thank you for the information sir. But can you take too much vitamin b12 — not because of toxicity — but because of excess b12 wasted through the urine? Supplements aren’t cheap where I come from, and I’m afraid to taking too much b12 vitamin doses and getting the same effectiveness as if I took smaller doses. Your advice appreciated.
Yes, absolutely. While vit B12 toxicity is no issue, you can get wasteful with your supplementation. That’s why I recommend smaller, more frequent doses instead of large weekly doses (for example, daily 1,000mcg instead of weekly 10,000mcg doses, especially with injections — which are already less wasteful than any other form of B12). This will help you get less excess of vitamin B12 in your urine.
Someone at my hosptal has a rare condition of too much b12. They are trying to figure out why. Any answers
I read in the Mayo Clinic web site that B12 is stored in the body and can cause symptoms when too high.
High doses of vitamin B-12, might cause:
Dizziness
Headache
Anxiety
Nausea
Vomiting
Hey Renee,
I hope you will read this :) I just read your reply about someone lying in the hospital with a rare condition of havin too high levels of B12? Do you know the name of that condition? 2,5 years ago I had a B12 “intoxication”: 1 week after taking quick-melt tablets I collapsed and had about 40 symptoms. Before that week I felt alive and healthy for about 95% and after that 1 week of B12 tablets (high dosis tablets) I felt scarcely alive. For 1,5 years I was afraid I would die from that condition. I’m still not sure what happened and why that high dosis of B12 cause these extremes symptoms for me. Thanks.
Hello, I’m also interested to find out more about this condition. I had a severe reaction a little over a year ago. Broke out in a rash that got worse over the days and severe itching and pain. Long story short after visits to my general doctor then dermatologist, no one could figure out what was causing this. It got so bad I ended up in the ER. I asked about B vitamins but was told not possible to have this kind of reaction. It wasn’t until I stopped taking my B vitamin supplement did the rash start to clear up. A year and a half later and I still notice sensitives when having energy drinks or if I try to take a multivitamin
Currently my 3 year old has been very sick,we wanted to make sure she was not low on her B12 but to our surprise she has 1,200 which is high,we are very scared now
What if I’m pregnant? Can you overdose on vitamin b12 if your’e pregnant? thanks!!!!! Please answer fast.
There are no side effects of too much b12 whatsoever. You should be more worried about not having enough B12 — rather than too much — when pregnant. It is extremely important for the development of your child.
Have an easy, safe pregnancy.
Hi,
I recently contracted shingles and decided to take high doses of Vitamin B12 sublingual and also an injection. Following this input of Vitamin B12, I have experienced severe numbness and muscle cramps in both legs, I am a fit runner and only mid 40’s. This has led me to believe that Vit B12 caused these leg symptoms…any comments appreciated.
Rob
Rob I have read that these symptoms were normal after a deficiency because it’s related to the nerves starting to heal. Just continue treatment and after a few weeks it will get better. See it like that: you had a problem but you weren’t feeling it, the body starts to correct the problem and as nerves are involved you suddenly just feel it more while it is getting better
Hi, just wondered if your symptoms have gone? I’m also experiencing numbness after b12 injections and no one is taking me seriously when I mention about side effects. No one replies or updates on here
Had to much b12. Stiff all over, numbing in hands and feet haven’t had a shot in 4 months. Feel like I’ve been ran over.
I too experienced this and much more. It is indeed possible to overdose on b12.
I started a new supplement with a high content of Vitamin B12 a week before having blood work done for a neurologist appt. At the appointment I was told to stop taking immediately because it was causing Neuropathy in my right leg, feet and hands. This can cause a disconnect between the brain and the feet.
Have you had skin itching and burning symptoms randomly on your body as well.
I started taking high amounts of B12(6,000 iu) because my naturopath suggested it and I ended up with Neuropathy!!!! Numbness tingling burning pain in feet!!!!!!! The specialist doctor said to go off the B12because it has caused nerve damage!!!!!! It will never go away!!!!!! My life is pure hell so people pay attention, too many vitamins is not good
Hi, I accidently took a double dose of B12 vitamin pills, because I’m used to taking a lower dose. The next day my face and neck broke out in hives and has remained for 2 days. I looked this up, and this appears to be a side effect people experience.
I feel like it’s a discomfort worth noting, so people will be careful. Thanks.
A lot of the comments seem to share similar experiences and symptoms associated from what is believed to be a toxic level of B12. Unfortunately, I can’t answer your queries directly, and I am not a Dr., but let me suggest regardless, it isn’t possible within the scope of this commentary to provide the answers you seek. The fact is, without more details, comparison and contrast of different cases, etc. , it isn’t even plausible to provide an educated guess on a conversational level. However, even with a casual look at some of the info provided two things certainly stand out: vitamin B12 is water soluble and therefore unlikely to cause any lasting negative effects (or positive for that matter, which is why it is necessary to repeat one’s dose on a fairly regular schedule), and second, many of the negative side effects described by others in this section bear a strong resemblance to symptoms of allergic reaction, which ultimately can be attributed to any number of variables present at the time of B12 ingestion. For example, let’s say the B12 consumption in question was not delivered by injection but instead in the form of a tablet which will also contain any other number of ingredients for fillers, binders, colouring, etc., and which some may be sensitive to. If B12 is ingested in a multivitamin form instead, the list of potential sources for a reaction becomes quite formidable. In fact, the B3 vitamin, Niacin, is well known to cause some similar complaints mentioned here when taken in doses not much higher than what is normally provided in most multivitamin or complete B complex formulas. I hope this gives some insight into the problematic nature of pinpointing cause and effect within the constraints of this environment and without much broader and more detailed data, but perhaps offers some additional points to ponder while continuing the quest for answers. Best wishes for good health!
I had a hemicolectomy I 1984 and take B-12 shots. The slow melt tabs or any vitamin 12 pill in mouth are useless . Vitamin 12 destroyed before it reaches blood stream. Must take with needle. If taking as a part of a diet routine they put a bunch of other stuff in it. This caused my 100 pound sister to have many undue symptoms. She asked them and then they said. It was a diet enhancer including B-12 and homer things like honey?, etc.
I am betting all of you got sick from slo-melts and shots DID not have pure Vitamin .B-12. But a mixture of untested and unneeded items that were useless and you were allergic too.
My doctors said No B-12 by mouth!!!!
Is methylcobalamin better than cyanocobalamin?
Yes, if you’re interested why read my article on methylcobalamin vs cyanocobalamin.
Please help I TOOK 1000 mcg for 10 days and I’m numb all over ..fatigue anxiety ..even my neck injury doesn’t hurt ..I think NERVE DAMAGE
Hi Emily,
Have your symptoms gone ? I’m experiencing the same
I disagree. I just discovered I am homozygous MTHFR and my doctor had my increasing my Methylcobolamin by 1000mcg every week. When I got to 400mcg, I had terrible headaches, my head felt like a balloon blowing up, and I developed hives, anxiety, and nausea. Yes, B12 can have side effects.
I WAS DIAGNOSED IN 2014 WITH CLL. SINCE THEN M Y b12 IS VERY HIGH AT 1200. IS THIS BECAUSE OF THE CLL? I THIS NORMAL?
Possibly you are not absorbing the B12. Or you may need a different form. Just a thought.
What is CLL?
I have been taking 2000mcg of vit b12 pills a day for sciatic nerve pain and 300 mcg of vitb 6.
It has helped this pain ( doctor recomended. Bur for a week or so head pain, pressure and numbness, prickling on my face.
Any thoughts?
B6 is neurotoxic. 300mcg is a massive gigantic dose of B6. At this point any issues you have have a high chance of being vitamin b6 toxicity.
Check the other ingredients in the B12 supplements especially the liquid drops. Some of them have preservatives, potassium sorbate, food colorings, etc., that may be causing reactions if you have sensitivities.
Ina e been having B12 shots for many years and wonder if my itching on my arms and legs is caused by too much B12?
I’m in big trouble after taking B12 supplements for years. My levels are off the scale and yet I am healthy in other respects.
This has caused severe itching. I have left off B12 for a month now and still not improved.
Hot skin and face and irritated eyes Having to use anti itch creams cold showers and ice packs to get through the day.
Drinking heaps of water and eating less dairy and having green leafy veggies to help my body along with this nightmare.
Hi Lyn
Has your itching improved since your last post.
Was taking a supplement with high b12 but only for several months. Have had facial and body itching since. Quit taking several days ago and hoping symptoms go away.
im a compound hetero for mthfr. my b12 levels are 4x the normal range. i was taking cyanocobalamin for years not knowing that it was actually bad for me. i have switched my b12 to hydroxy (since finding out about mthfr) since i also have vdr and comt mutations. how can i detox b12 so i can start using the good kind efficiently?
Niacin
I’ve been taking methyl b complex and ended up with severe diarrhoea and optic neuritis. I had some unrelated health problems but was basically fine before I started taking it but apparently my liver needed ‘support’ according to a nutritionist. I’m pretty certain it’s the vitamin b complex as I had diarrhoea every day for a month while taking it and within 2 days of stopping it had completely gone back to normal, and my eye is getting better.
I think it’s dangerous to state there are absolutely no side effects from overdosing on a vitamin when the possibility of nerve damage and other symptoms from b vitamins are widely discussed on the internet and clearly many people have experienced them. At the very least, this article should advise people to confirm they have a deficiency before taking it.
I agree with you. After taking 2000 mcgs of b12 daily for 2 years I developed neuropathy in my feet, tingling and burning. My b12 level is 1200. I am going to stop taking it and hope the symptoms are reversed. I have been tested for everything else including diabetes and it comes up negative.
If you have a high b12 test and took a supplement is the test valid?
Hi! How much µicrograms are 2500 IU?
Can you overdose on B12 if it’s not Methylcobalamin you’re taking?
We need to trust our inner sense and honor it if something feels like too much.
It is possible for anything to be done to excess. Anything. Even water.
Hi! I occasionally get migraines and used to break out in oral herpes maybe a few times a year. The herpes hasn’t really happened in a year and a half, and the migraines have been fairly mild. This week, though, I’ve drastically increased my supplementation of B-Complex (the B12 is 50000 times the daily value). I’ve had migraines like never before (full vision loss rather than partial, cotton mouth, nausea, dizziness), a herpes outbreak (just the sores but none of the normal systemic symptoms, high anxiety, nausea all week, super sensitivity to natural energy drinks, fatigue, hand numbness while asleep, sore throat, and jaw pain. I eat keto and do intermittent fasting (haven’t done IF this week). My husband and I are trying to conceive so it’s worrying us. We’re natural minded, and every doctor just wants to load me up on pills. I stopped the B-Complex yesterday.
I have been taking Vitamin B-12 for a while now. The first times were because my Blood Platelet reading was low and it perked it right up.
It also helps to stimulate your brain among other positive results. Recently
I started taking a new multi-vitamin 1,000 mcg and when I checked the B-12 content it was 41,667% of my daily serving requirement. I had also been taking a B-12 pill 100 mcg (1667% of my daily serving requirement.
Both of these contain cyanide. I also started taking arm of B-12 (no cyanide) and it has2500 mcg (104,170% of my daily serving requirement) to replace my first version. Now my Blood Platelet count has dropped over 40 points below the bottom of the norm.
How much b12 is too much if I’m pregnant?
I have weakness of my limbs, sometimes painful in the night , numbness and almost lose of balance whilst walking for a while.I have diabetes for 10 yrs now,pls can I take the bit b 12 you’re talking about?? Felly
What is that letter that looks like a typo that follows the dosage amount in this vitamin story?
A microgram is a metric unit of mass equal to one millionth (1×10?6) of a gram. The unit symbol is ?g according to the International System of Units. The exception is found in the antiquated and almost obsolete system of Imperial measurement , such as stubbornly remains in use in the United States, where the recommended symbol when communicating medical information is mcg.
Obviously, I am replying using an English (U.S.) keyboard rather than an English (UK) version, or rather than the true typos appearing in my response you would see the same symbol that appears in the article. Hrumph!
What happens if i took 6 of them on one sit ?
Seriously Ray? Now why would u want to go and do a thing like that? It would be just wasteful Ray. Such a sad and unnecessary waste.
Hi, my son is diagnosed with mitochondriopathy and we were advised to have 300 mg of b12 per day.. Yes its mg not mcg. Can you recommend a brand where i can buy preferrably not the injectable type. Thanks!
Here to tell you first hand there ARE ill effects of taking too much B12. Too much can cause high blood pressure. I naturally run B12 deficient but am able to supplement just fine without injection and I felt GREAT after doing it. BUT there DOES come a point where the deficiency has been corrected and it’s time to come down to a maintenance dose. I’ve currently noticed headaches, dizziness and at the recent doc visit high blood pressure for the first time EVER. My Normal b12 is about 30-1800 mine is currently 3162. WAY too high. Skipped my b12 pill today and it’s the first day without headaches, surprise surprise. Never going to stop taking it completely but it IS a vitamin people need to be careful with.
I had broken out in a rash that started on my elbows and then my knees. Around this time, I was getting a lot of headaches Dermatologist initially told me I might have psoriasis and took a biopsy which was inconclusive. Showed inflammation with could mean psoriasis or eczema. It eventually all healed after a couple of weeks, but then round 2 started. It really took off all over my arms and legs. Most of the spots originated at night when sleeping. It seemed like heat, or the friction from moving or where my arms and legs were folded would break out. These areas itched like crazy to the point where I wanted to rip my skin off. For 2-3 weeks I was only sleeping a couple of hours at night. I was going crazy. During this time I had seen my primary doctor and dermatologist each twice. My primary doctor finally referred me to an allergist/immunologist. The night before going, my pulse was racing in the 120-130’s and I felt like I had a fever even though my temperature was normal. I almost went to the ER. When she finally saw me, she looked at me like I was dying. She ordered a lot of blood work that all came back normal (thank goodness). Up until this point it had been going on for about 2 months and I was becoming desperate to find a cause. She finally ordered a scratch test and a patch test. The morning I was scheduled to start all the allergy testing I woke up, and my symptoms just all stopped. Today I got the preliminary results which showed I’m allergic/sensitive to Cobalt.
They gave me a couple of sheets describing things that might exacerbate the reaction. One of them that stood out was vitamin B12 (as cyanocobalamin). Up until I started with all these symptoms, I was taking pre-workout drink, post-workout drink and vitamins. When I tallied this up, I was taking upwards of 1000-1500% of the daily recommended value. I have been doing this for about 6-8 years. I can’t be sure that this was causing my symptoms, but it is by far the one thing that stood out. The only other thing and maybe its in combination, is stress. I have had way too much of it in my life around the time this all started. Mom has pancreatic cancer, work two jobs and take call, etc, etc. I started exploring vitamin B12 reactions and came across this site. At the beginning of this post it goes on to say that you can’t be allergic or sensitive to vitamin B12, and that is just not true if you are allergic/sensitive to Cobalt. Only Vitamin B12 in natural form (methylcobalamin) is recommended. My findings are only preliminary, but I wanted to share in case this helps someone. I know how we can become desperate to find answers, and small snippets can sometimes become pieces of a puzzle we are trying to solve. I would start with Cobalt sensitivity/allergy for anyone trying to find a reaction to B12.
My mother is of age 72 and has very high B 12 i.e 1235. Is it harmful for her.
She has also high Rumathoid Arthritis. Is that is of high B12.