Vitamin B Overdose – Symptoms, Dosage, Effects, Causes, Diagnosis & Treatments

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.

21 comments on “Vitamin B Overdose – Symptoms, Dosage, Effects, Causes, Diagnosis & Treatments

  1. praveen kumar says:

    really a lot of important informations got with this article

  2. Timothy Spennicchia says:

    I am always taking vitamin B6 supplements for nerve support. Its really great. :.::,

    My own blog

    • M says:

      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.

  3. Dora Chaudoin says:

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

    • Laura says:

      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.

  4. Bruno Debreto says:

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

    • Michelle says:

      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.

      • Anonymous says:

        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

      • YI says:

        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.

  5. Carl Mannella says:

    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. ,

  6. bea says:

    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 :/

  7. leslie says:

    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

    • Bea says:

      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.

  8. Bob says:

    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.

  9. august says:

    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.

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  11. The red lobster tale says:

    […] After figuring out that the B1 MUST be the cause, I finally DID find some stuff online about overdoses of B vitamins, including B1, and an explanation of what is happening from […]

  12. brenda says:

    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.

  13. brenda says:

    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.

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