Vitamin B Overdose – Symptoms, Dosage, Effects

Vitamin B

Vitamin B overdose levelsB Vitamins or also called Vitamin B Complex.  These mainly consist of eight B vitamins including four additional vitamins.
Vitamin B complex consists of:

  1. Thiamine (Vitamin B1)
  2. Riboflavin (Vitamin B2)
  3. Niacin (Vitamin B3)
  4. Panthotenic acid (Vitamin B5)
  5. Pyridoxine (Vitamin B6)
  6. Biotin (Vitamin B7)
  7. Folic acid (Vitamin B9)
  8. Cyanocobalamin (Vitamin B12)

Other B vitamins include:

  1. Niacinamide (Vitamin B4)
  2. Inositol (Vitamin B8)
  3. Para Amino Benzoic acid (Vitamin B10)
  4. Choline (Vitamin B11)

Among these, the most individually used B vitamins are Vitamins B1, B6, B2 and B12. The daily requirements for these vitamins can be taken from natural food sources such as green leafy vegetables, lean meats, organ meats and legumes.

In individuals with poor oral intake and unable to get much of the B vitamins in food, a dietary supplement may be taken. The lack of vitamin B in the body leads to deficiencies in the form of pernicious anemia, megaloblastic anemia and peripheral neuropathies.

Vitamin B should be taken as a dietary supplement following the prescription of a doctor. Vitamin B complex is water-soluble; thereby it is excreted through the urine. However, any excessive intake of such, higher than the upper tolerable limit may cause over dosage and health consequences.

Vitamin B Overdose Levels

The recommended intake of B vitamins is based on the table below. Any excessive intake beyond this limit may cause over dosage.

Age Group Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B6 Vitamin B9 Vitamin B12
Infants below 6 moths 0.2 mg 0.2 mg 2 mg 0.1 mg 65 mcg 0.2 mcg
Infants 6 to 12 months 0.3 mg 0.4 mg 4 mg 0.4 mg 80 mcg 0.4 mcg
Children 1 to 3 years 0.5 mg 0.5 mg 6 mg 0.5 mg 150 mcg 0.5 mcg
Children 3 to 8 years 0.6 mg 0.6 mg 8 mg 0.6 mg 200 mcg 0.7 mcg
9-13 years old 0.9 mg 0.9 mg 12 mg 1 mg 300 mcg 2 mcg
Above 14 years old and Adults (men and women) 1.2 mg 1.3 mg 14 mg 1.3 mg 400 mcg 2.4 mcg
Pregnant and Lactating Mothers 1.4 mg 1.6mg 18 mg 2 mg 600 mcg 2.8 mcg
Therapeutic Range 50 mg to 1,000 mg 50 mg to 500 mg 100 mg to 2,000 mg 100 mg to 2,000 mg 400 mcg to 20,000 mcg 100 mcg to 10,000 mcg
Over dosage Level or Tolerable Limit Above 1,000 mg Above 500 mg 10 mg to 35 mg 30 mg to 100 mg 400 mcg to 1,000 mcg Above 10,000 mcg

Vitamins B1, B2, B3, B6, B9 and B12 are the most common types of B vitamins that can cause over dosage. Other types of B vitamins are tolerated well by the body and are usually not given through oral supplementation. They occur naturally in foods.

Signs and Symptoms

Being water soluble vitamins, Vitamin B complex is not stored inside the cells; rather they are excreted in the urine. Because of this, the risk for over dosage is not likely. However, when normal individuals do not need high amounts of vitamin B exceeding the tolerable limit, they are usually at risk for developing over dosage. Over dosage from the B vitamins causes osmosis of water from the interstitial space to the intravascular space in order to dilute the large doses and promote excretion through the urine. Symptoms of Vitamin B over dosage include:

  1. Increased thirst
  2. Flushing of the skin
  3. Excessive urination
  4. Diarrhea

These symptoms are the compensatory mechanism of the body to eliminate the excessive vitamins through the bladder and bowels.

Specific symptoms related to the overuse of the B vitamins include:

Vitamin B1

  1. Skin rashes
  2. Allergic reactions
  3. Agitation
  4. Insomnia
  5. Heart palpitations

Vitamin B2

  1. Fatigue
  2. Vomiting
  3. Nausea
  4. Hypotension
  5. Dark-Yellowish urine

Vitamin B3

  1. Headache
  2. Skin rash
  3. Flushing
  4. Joint pains
  5. Nausea and vomiting
  6. Insomnia

Vitamin B6

  1. Numbness on the extremities
  2. Tingling sensation
  3. Muscle cramps
  4. Restlessness
  5. Fatigue
  6. Mood swings
  7. Insomnia

Vitamin B9

  1. Bloating
  2. Anorexia or decrease in appetite

Vitamin B12

  1. Unilateral tingling sensation
  2. Panic Attacks
  3. Insomnia
  4. Palpitations

Long-term Effects of Vitamin B Overdose

Over dosage of B vitamins also lead to complications or long-term effects. The complications also vary according to the specific B vitamins. These include:

Vitamin B1

Over dosage of Vitamin B1 produces a negative effect on the heart and brain. The most common long-term effect is hypertension and palpitations. Aside from these, the brain also is over stimulated leading to mood changes and agitation.

Vitamin B2

The primary complication of Vitamin B2 over dosage is anemia.

Vitamin B3

An overdose of this vitamin can result in hyperglycemia, hyperuricemia, jaundice, calcium loss and hyperacidity.

Vitamin B6

Excessive vitamin B6 in the body can yield hypertension, palpitations, mood problems and hypoglycemia.

Vitamin B9

Just like vitamin B2, the result of vitamin B9 excess is anemia. Both deficiency states and excessive levels of B9 can result to anemia.

Vitamin B12

Excessive levels of cyanocobalamin can cause hyperthyroidism.


Causes and risk factors for vitamin B overdose include:

Excessive Intake

The main cause of Vitamin B overdose is a high supplemental intake of the B vitamins. Over dosage does not usually result from dietary or food intake rich in Vitamin B complex.

Instead, the oral supplementation can yield such. Physicians prescribe the right amount of B vitamins to be taken according to the case of the patient. Normal individuals do not usually need supplements because B vitamins are readily available from food sources.

Kidney problems

The Vitamin B complex is excreted from the body through urine. Chronic renal failure may result in over dosage in people taking vitamin B supplements in large amounts because of the inability of the kidneys to adequately form urine and release toxins in the body.


Diagnosis begins with a complete medical history to assess any intake of Vitamin B pills. The medical history is also checked to determine any underlying diseases requiring Vitamin B supplementation such as pernicious anemia, megaloblastic anemia or peripheral neuropathies.

A serum test is usually done to determine the exact amount of the vitamins in the blood.


Treatment regimens for vitamin B overdose include measures to enhance the elimination from the body. Treatments include:

Discontinuing the Vitamin Supplementation

The initial step in any drug over dosage is stopping the intake of the drug. Patients should immediately consult a physician for symptoms to immediately stop the administration that would further intensify the condition when patients are not informed of an over dose.

Induce Vomiting

The emergency measure for ingestion of large amounts of Vitamin B is to induce vomiting as soon as possible to prevent the movement into the intestines and prevent absorption. Vomiting is induced using medications. Alternatives include warm water mixed with high amounts of sugar.

Increase Fluid Intake

Vitamin B is water soluble hence; they are eliminated in the urine. To enhance this, patients should take high amounts of fluids in a relative short period of time to flush the vitamins out of the body. Intravenous fluids may also be given to increase circulating blood volume and increase the glomerular filtration rate (the rate of blood flow to the kidneys and the production of urine).

Activated Charcoal Administration

Activated charcoal functions as a medium where the excessive toxins will adhere. Activated charcoal adsorbs (particles attach to the surface of the charcoal) the toxins to prevent absorption in the intestines.

Since the B vitamins are already attached to the charcoal, it is then eliminated through the stool. Sometimes, a gastric lavage is done to evacuate the activated charcoal with the toxins from the stomach.

Gastric Lavage

Gastric lavage involves the instillation of normal saline solution through a tube from the nose going to the stomach. The fluid washes off the surface of the gastric mucosa. The fluid is then aspirated again and another instillation is made to make sure that the stomach is clear with the toxins.

To prevent Vitamin B overdose, it is important to adhere to the prescription of the doctor.

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51 thoughts on “Vitamin B Overdose – Symptoms, Dosage, Effects

  • 30/09/2012 at 11:14 pm

    really a lot of important informations got with this article

    • 16/03/2014 at 8:43 pm

      Some people are susceptible to B6 overload, which actually interferes with nerve function to cause numbness in hands and feet, cold hands and feet, loss of coordination and balance, etc. It can take months to overcome this (B6 is stored by the body, and only very slowly eliminated by the liver). In some cases, the nerve damage can be permanent.

      • 23/07/2015 at 6:22 pm

        I am one who took B6 for a couple of months and suffered severe overdose. All of the symptoms including chest and stomach discomfort. They say it takes at least 6 months to 3 years for the symptoms to go away (if they do go away). I do not recommend taking any vitamin unless you know you are deficient. I was taking a B complex and had NO idea that B6 could do this to the body. I look forward to the day without nerve pain or discomfort.

        • 31/07/2015 at 2:06 pm

          Yes, Jill. This happened to me also. I’m slowly getting better but it’s awful. The tingling, burning, pinching, itchy feelings (mainly on my feet) have been enough to drive me crazy. Coupled with this is the fact that I am a RN — so I know these symptoms can be attributed to other conditions. It’s been a walk through hell. I only took some of the “Emergen—C” effervescent drink for 2 weeks and it did this to me. My family doctor was not aware that short term high doses of B6 could cause neuropathy. It was only after I saw a neurologist that I was made aware this was even the cause. From what I’ve heard, many neurologists are not even aware! Also, as an FYI: In the UK (and possibly many other countries) no one can get any dose over 15 mg per day without a prescription!!! In the USA, we have MASSIVE amounts of B Vitamins in all kinds of supplements, protein drinks, energy drinks and cold and flu preparations! Not too mention adding it to MANY foods such as cereal, nuts, and potato chips of all kinds!!! Check the labels, it’s frightening. Good luck to you. I hope this neuropathy is reversible too! These people that praise this pointless poison are ignorant. They think it gives them energy and that’s BS. It’s the placebo effect. The risk outweighs the benefit – by a long shot!

          • 16/06/2016 at 4:45 am

            Iam suffering from b complex injection which I took on 24/7/2015 all the overdose ‘s symptoms happened to me from that date till now my brain is active so I can’t sleep four hours and I feel with discomfort all the time and general pain , can’t concentrat , anxiety, swing mood panic attack and many things I can’t discribe but the weired is a lot of doctors don’t know about the side effect they think that it will absorb in water and come out by ruin which is traditional thoughts but few doctors know that it has rare side effect ( from overdose)and it will take from one year to 18 months so the nerve will heal and recover and back to normal really it awful so Iam suffering till now and Iam waiting to recover from it. But I want to advise all people u have to test vaitamin b in the blood before taking it if u have deficiency take it but if u don’t have don’t take it at all and all the people think that b give u energy yes it gives u a lot of energy but when increases it will make u crazy from its symptoms

          • 16/06/2016 at 5:01 am

            Iam suffering from b complex injection which I took on 24/7/2015 all the overdose ‘s symptoms happened to me from that date till now my brain is active so I can’t sleep four hours and I feel with discomfort all the time and general pain , can’t concentrat , anxiety, swing mood panic attack and many things I can’t discribe but the weired is a lot of doctors don’t know about the side effect they think that it will be absorbed in water and come out by ruin which is traditional thoughts but few doctors know that it has rare side effect ( from overdose)and it will take from one year to 18 months so the nerve will heal and recover and back to normal really it awful so Iam suffering till now and Iam waiting to recover from it. But I want to advise all people u have to test vaitamin b in the blood before taking it if u have deficiency take it but if u don’t have don’t take it at all and all the people think that b give u energy yes it gives u a lot of energy but when increases it will make u crazy from its symptoms

  • 26/11/2012 at 8:57 am

    We always need vitamin-B complex everyday to increase our vigor and energy. ^

    • 21/09/2013 at 2:34 pm

      Just be careful with the percentage of the B complex. I had a B 100 and overdosed severely on it several times not realizing what was happening and thought it was just allergies. Some bottles are extremely high.

  • 26/11/2012 at 9:00 am

    Vitamin-B12 is very essential for nerve health, i always take large amounts of it. `

    • 24/07/2013 at 1:24 am

      Please be careful!! My doctor did not check my blood levels before administering 3 months of mega doses of B12. As a result, I lost my memory, my kidneys are compromised, and my hands and feet feel like they are asleep ALL the time. I am still suffering over this.

      • 10/12/2013 at 4:48 pm

        Hi Michelle .my daughter could not store b12 and was put on injections she now is overdosed .and showed 1800 mg how long have you been suffering. The doctor said 6 months

        • 09/04/2016 at 8:55 pm

          I think I am overdosed too on b12. Please I would like to talk to you about what happened. How long till ur daughter felt better? Help!

      • 04/06/2014 at 9:37 am

        Hi, Michelle, Are you still suffering that? Is there any numbness in your hands and feet? I think I have the same symptom. I am not sure it is overdose.

  • 26/11/2012 at 9:08 am

    Vitamin B6 is necessary for the health of the brain neurotransmitters. It also helps in the production of serotonin which is the feel good hormone. ,

  • 14/02/2013 at 12:29 pm

    I live in the uk, i was given vit b complex and was taking multi vits. I didnt realise til afterwards that the rda in the multi vits was 100pc on all,it b vits. I began to itch, tingle and orange urine. My gp and pharmacist said it cant he iverdose as its water soluble. Please help, im worried :/

  • 21/02/2013 at 2:42 pm

    I have taken an overdose of B6 and lost sensations in my legs. Not taking B6 anymore, worried as to when I will get my feeings in legs back and if at all? I took nearly 100mg daily for a month, stopped 2 weeks ago. Pls help/advise

    • 25/02/2013 at 2:21 am

      Hi Leslie, did it happen straight after taking the supplement or a while after? Did you get any other symptoms? Go see your gp, but I warn you some GPS don’t know about vit b overdose. Try speaking to a pharmacist or email me I have a really good book about b6 overdose.

  • 24/07/2013 at 3:27 pm

    Hi Bea,
    What is the name and author of the book that you have on B6 overdose? I was taking a B-Complex with 50 mg of B6 (as P5P) for about 5 months. Started having numbness and tingling in toes soon after but took a while to link it to the B6. I stopped taking B6 about 3 weeks ago and the burning, pain and twitching are still spreading.

  • 12/09/2013 at 2:44 am

    I’ve read everything my daughter has to much b 12in her body.we checke
    d everything on the internet. Because people don’t have enough in b12
    in their system normally, food Packers put extra b12 in all the food.
    to counteract b12 take patassium,no more than 4000 a day. Don’t believe me
    check it out yourself . Happy sailing hope it work.

  • 25/10/2013 at 6:58 am

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  • 20/06/2014 at 8:37 pm

    I have neuropathy; espec. in my feet. I heard of big doses of B complex so I started 3 days ago. Since then, I noticed my feet didn’t tingle anymore and they did 24/7 previously. But then I started thinking about overdoses, so I’m glad I found this site. Think I will take one every other day for a while. Feet still “hurt” but dont tingle.

  • 24/07/2014 at 4:24 pm

    Tingling in hands and feet are first signs of neuropathy. Like I said, no tingling on the B complex but still have pain that seems to be marching up my legs. In my calves even b4 I started B’s.. B’s are supposed to help but I am being careful about how much I take.

    • 02/05/2015 at 1:28 am

      Hi Brenda,
      I have peripheral neuropathy and am taking big doses of B complex but still have pain in my legs and
      Can you let me know if cutting down on the dosage has helped your symptoms?
      And, if you can, tell me how much you are taking.
      I would very much appreciate your reply.
      Thank you.

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  • 11/05/2015 at 7:11 pm

    Can you give me references for the information you cite on this page? I have never seen this information before and would like to read any literature you might have on this topic.Also please list the credentials of the person who provided this information.

  • 31/05/2015 at 2:13 pm

    I was asked about how much B complex I was taking. First, Nature Made (W’mart) Super B Complex:
    Thiamine 100 mg
    Ribof. 20 mg
    Niacin 25 mg
    B6 2mg
    Folic acid 400 mcg
    Vit b12 15mcg
    Biotin 30 mcg
    Parth acid 5.5 mg
    They stopped the tingling immediately. Then I read about over dose. Went to see local Vitamin expert and she encouraged me to stop taking some of this and some of that supplement and take a complete choice of what women ove 50 need. This does the trick too and the Neuropathy doesnt seem to be getting worse. It is BLUEBONNET Age-less Choice whole food based multiple for Women over 50.
    Check it out if you are over 50.

  • 31/05/2015 at 2:15 pm

    Forgot to say that cutting down to every other day DID keep my feet from tingling.
    I WILL say that my hands tingle some at nite when they are in a certain position. Could be my circulation too I guess.

  • 25/08/2015 at 5:49 pm

    I took an overdose of Vitamin B Complex unknowingly for the past 4 days and developed a severe headache, stomachache, loss of appetite and frequent urinating. Am really worried. However I have been taking a lot of water for the past two days and discontinued the intake.

  • 25/09/2015 at 3:56 am

    Hi I received an overdose adverse reaction to shot of b12 and now have adrenaline and insomnia for a month and a half with increased blood pressure and heart rate. Does anyone know if these symptoms get better or do I have to live the rest of my life not sleeping? I’m usually big sleeper this is a nightmare from a vitamin.

    • 05/11/2016 at 2:36 am

      I too am experiencing the same thing. Have your symptoms gotten better? Have you tried Niacin?

  • 26/09/2015 at 10:08 am

    “Excessive levels of cyanocobalamin can cause hyperthyroidism.”

    I really would like to see the medical research that supports what you have written above.

  • 02/11/2015 at 2:10 am

    There is now a support group for B6 toxicity on Facebook. Please search Facebook for B6 Toxicity.

  • 13/11/2015 at 11:07 pm

    I wish I could go back in time! Like most, I believed B vitamins were water soluble and extra would be excreted. Apparently not!

    Finally, after four+ years of foot numbness, I get tested and find out I am over lab range for B1, B2, B6, and Folate. Yes, I’ve been supplementing like crazy since year 2000!

    10/2015 lab results:

    B1: 216 nmol/IL (78-185)
    B2: 41.9 nmol/IL (6.2-39.0)
    *B6: 46.6 ng/mL (2.1-21.7)
    B12: 1092 pg/mL (200-1100)
    Folate : 24 ng/mL (3-17)

    No wonder for the feet numbness, plus muscle weakness, etc. Let’s see if I ever recover. I realize the results could be a lot wirse. Thankful they are not and now I know.

    There is a B6 toxicity Facebook group :

    Best wishes, everyone.

  • 13/11/2015 at 11:09 pm

    Apparently, B6 is stored in muscle…

    B6 Stored in Muscles: We have proof that B6 is stored in the muscles. Translated this means that B6 is not water soluble (you urinate it out) as everyone has told you all your life. This information is important to toxicity. If it’s stored then we can get toxic at lower levels of supplementation or diet.

    B6 In Muscles Doesn’t Get Replaced Quickly: We also have proof that the B6 that is stored in the muscles does not get accessed when your blood supply is low. This means this stored B6 is STUCK in your muscles until YOU do something to pull it out.

  • 27/02/2016 at 5:00 am

    Has anyone experienced neuropathy in their tounge? I’ve been troubled with a burning sensation for well over a year and finally visited my GP, blood tests indicated vit b toxicity. Just wondering if it’s a common issue.

  • 29/02/2016 at 6:14 pm

    So sorry to hear this. No, I have not. Wonder how much you’ve been taking. I take a multivitamin one day and B Complex the next day.

  • 01/03/2016 at 12:27 pm

    And don’t drink energy drinks that contain B vitamins!!! It is WAAY too easy to get hooked on the caffiene+B zip those things provide at first, and end up really sick, dizzy, fatigued, befuddled from a vit amin B overdose. Switch to tea or coffee if you must have a boost, drink more water than you do tea or coffee, totally ditch all energy drinks, and exercise daily, even if it’s just a quick walk around the block. To help get rid of built up B vitamins, eat plenty of celery, bananas and (boiled/baked) potatoes. And if you feel like it’s not just a minor illness or a one-time thing, if it’s an ongoing issue, then talk to your doctor.

  • 09/04/2016 at 8:39 pm

    Please any information on too many b vitamins. I had about 10 b12 injections in the last 5 weeks, as I tested very deficient. 1000mcg a shot. Plus about 5 b complex pills a day. After 3 weeks I started to feel normal for a few days, so I thought great, I’ll continue this treatment. I started getting worse, I figured it was just my body levelling out, it’ll go away. Got worse and worse before I realized the shots were making me feel worse. Everybody told me bit bs are wAter soluble, u can’t overdose. But now I’m not so sure. How long before the b12 injections get out of my system?
    Please please any info….

    • 22/11/2016 at 9:18 am

      Hi Sarah,
      Did you ever got more information on the B12 overdose? I am going through the same thing, started about 3 months ago, read I need to drink lots of water and avoid meats, but I’m still very weak, unable to work.
      Does anyone know what else I could do to help get rid of the excess B12? Or what helps with the symptoms? I’m constantly having diarrhea, nausea, and extreme weakness, feel like passing out often, very desperate here, anybody knows anything on this that can help? Desperate for help here. Thanks!

  • 10/08/2016 at 11:37 pm

    My tongue, right arm & hand, right lower leg and right toes are all numb. I was told I had a stroke, but it was never verified medically. I also was having nail bad splitting on both hands and, thinking it was a vitamin problem started taking vitamin B complex. I also drink a lot of V8 and Propel. It was right after starting the B complex that the neuropathy started so I did some research. Then my heart doctor told me I had B vitamin toxicity. Now I think THAT is the problem rather than a stroke. I stopped taking the B complex and have cut back on the V8 and Propel and am drinking a lot more water, but haven’t noticed any change yet. It has been about a month.

  • 31/08/2016 at 11:14 pm

    I had three tablets of b complex , I have a chest pain and breathing problems , I m very scared what will happen after

  • 03/09/2016 at 10:38 pm

    Be extremely careful when supplementing B2 (riboflavin). The supplements come in high doses (over 100mg, mine was 250mg) and that is an absurd dose unless you have extremely serious deficiency. I cut my 250 in half and still had serious side effects. Excess B2 will cause liver damage, damage to your eyes, fatigue and disruption of serotonin processing. You will know if you are taking too much because your urine will become unmistakably neon yellow. If that’s the case, stop. If you must take it, start with 2mg. Be careful, this could induce cataracts in the eyes, as well.

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  • 16/12/2016 at 10:49 pm

    really great information..thanks

  • 26/12/2016 at 10:39 pm

    I started taking Vitamin B and D as I was having symptoms that fot the deficiency disorder and lab tests comfirmed that both vitamin levels were way to low. They started me on Vitamin B3 and Viatmin D (1,000 units each 4 times a day)… I am on day 6 and im nauseated, severe diarrhea, muscles and joints feel as if on fire and hurts to walk, headache and also legs swelling… Any advice on what to do would be great!!

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