Skip to content

    Find a Vitamin or Supplement

    VITAMIN B12

    Other Names:

    B-12, B12, B Complex Vitamin, Bedumil, Cobalamin, Cobalamine, Cobamin, Cobamine, Complexe Vitaminique B, Cyanocobalamin, Cyanocobalamine, Cyanocobalaminum, Cycobemin, Hydroxocobalamin, Hydroxocobalamine, Hydroxocobalaminum, Hydroxocobemine, Hydr...
    See All Names

    VITAMIN B12 Overview
    VITAMIN B12 Uses
    VITAMIN B12 Side Effects
    VITAMIN B12 Interactions
    VITAMIN B12 Dosing
    VITAMIN B12 Overview Information

    Vitamin B12 is an essential vitamin. This means that the body requires vitamin B12 to work properly. Vitamin B12 can be found in foods such as meat, fish, and dairy products. It can also be made in a laboratory. It is often taken in combination with other B vitamins.

    Vitamin B12 is taken by mouth to treat and prevent vitamin B12 deficiency, a condition in which vitamin B12 levels in the blood are too low. It is also taken by mouth to treat pernicious anemia, a serious type of anemia that is due to vitamin B12 deficiency and is found mostly in older people.

    Vitamin B12 is also taken by mouth for memory loss, Alzheimer's disease, to slow aging, and to boost mood, energy, concentration, mental function, and the immune system. It is also used for heart disease, clogged arteries and decreasing the risk of re-clogging arteries after surgery, high triglyceride levels, lowering high homocysteine levels (which may contribute to heart disease), male infertility, diabetes, diabetic nerve damage, nerve damage in the hands or feet, sleep disorders, depression, mental disorders, schizophrenia, weak bones (osteoporosis), swollen tendons, AIDS, inflammatory bowel disease, diarrhea, asthma, allergies, a skin disease called vitiligo, and skin infections.

    Some people use vitamin B12 by mouth for amyotrophic lateral sclerosis (Lou Gehrig's disease), multiple sclerosis, preventing the eye disease age-related macular degeneration (AMD), a condition in which the body products too much thyroid hormone, Lyme disease and gum disease. It is also used by mouth for respiratory tract infections, maintaining fertility, ringing in the ears, bleeding, liver and kidney disease, canker sores, preventing fractures, preventing stroke, preventing blood clots, and for protection against the poisons and allergens in tobacco smoke. It is also taken by mouth to prevent cancer, including breast cancer, cervical cancer, colorectal cancer, and lung cancer.

    Vitamin B12 is applied to the skin either alone or in combination with avocado oil for psoriasis and eczema. Also, a vitamin B12 nasal gel is applied for pernicious anemia and preventing and treating vitamin B12 deficiency.

    Vitamin B12 is injected into the body for pernicious anemia, to prevent and treat vitamin B12 deficiency, and to prevent and treat a nervous system disorder called myelopathy, which can occur in people who are vitamin B12 deficient. It is also used for tremors, to treat Imerslund-Grasbeck disease, cyanide poisoning, nerve damage caused by shingles, diabetic nerve damage, tiredness or fatigue, chronic fatigue syndrome, hepatitis C, a condition in which the body products too much thyroid hormone, bleeding, cancer, psoriasis, and liver and kidney disease. It is also injected in the body to prevent arteries from re-clogging after surgery.

    How does it work?

    Vitamin B12 is required for the proper function and development of the brain, nerves, blood cells, and many other parts of the body.

    VITAMIN B12 Uses & Effectiveness What is this?

    Effective for:

    • Inherited Vitamin B12 deficiency (Imerslund-Grasbeck disease). Injecting vitamin B12 as a shot for 10 days followed by monthly injections for the remainder of life is effective for treating people with an inherited disease that results in poor absorption of vitamin B12.
    • Pernicious anemia. Injecting vitamin B12 as a shot, as well as taking through the nose or by mouth, is effective for treating low red blood cell counts caused by poor absorption of vitamin B12.
    • Vitamin B12 deficiency. Taking vitamin B12 by mouth, through the nose, or as a shot is effective for treating vitamin B12 deficiency. Injecting vitamin B12 into the muscle is better than taking it by mouth if vitamin B12 deficiency is severe or nerve damage is present.

    Likely Effective for:

    • Cyanide poisoning. Administering hydroxocobalamin (Cyanokit), a natural form of vitamin B12, as a shot for a total dose of up to 10 grams is likely an effective treatment for cyanide poisoning. Treatment of cyanide poising with hydroxocobalamin (Cyanokit) has been approved by the U.S. Food and Drug Administration (FDA).
    • High level of homocysteine in the blood (Hyperhomocysteinemia). Taking vitamin B12 by mouth, along with folic acid and sometimes pyridoxine (vitamin B6), can lower blood levels of homocysteine.

    Possibly Effective for:

    • An eye disease called age-related macular degeneration (AMD). Some research shows that taking vitamin B12 with other B vitamins, including folic acid and vitamin B6, might help prevent an eye disease called age-related macular degeneration. But the effects of vitamin B12 alone on AMD are not clear.
    • Nerve damage from shingles. Some research shows that injecting vitamin B12 in the form of methylcobalamin under the skin six times weekly for 4 weeks reduces pain more than taking vitamin B12 by mouth or injecting lidocaine under the skin in people with nerve damage from shingles. Other research shows that it reduces pain and the need for painkillers. Adding thiamine to the treatment also seems to reduce itching.

    Possibly Ineffective for:

    • Cancer. Research suggests that taking vitamin B12 in the form of cyanocobalamin along with folate and vitamin B6, with or without eicosapentanoic acid (EPA) plus docosahexaenoic acid (DHA) does not reduce the risk of developing cancer in older adults with heart disease. Some research actually suggests that taking vitamin B12 and folic acid daily for 2 years might increase the risk of cancer in older people.
    • Sleep disorders. Taking vitamin B12 by mouth does not seem to help people with sleep disorders.
    • Mental function. Taking vitamin B12, alone or in combination with folic acid and vitamin B6, does not seem to improve memory, language, or the ability to organize and plan in elderly people.
    • Fractures. Taking vitamin B12 and folic acid, with or without vitamin B6 daily for 2-3 years does not seem to reduce the risk of fractures in older people with osteoporosis.
    • Stroke. Research suggests that people who consume more vitamin B12 in their diet or those who take vitamin B12 supplements do not have a reduced risk of stroke or stroke reoccurrence.

    Insufficient Evidence for:

    • Alzheimer's disease. Some early research suggests that higher vitamin B12 intake does not prevent Alzheimer's disease. However, other early research shows that taking vitamin B12 along with vitamin B6 and folic acid for 2 years might slow brain changes that are linked with mental decline and Alzheimer's disease.
    • Preventing re-blockage of blood vessels after heart artery dilation (balloon angioplasty). Research is inconsistent about the benefits of taking folic acid plus vitamin B6 and vitamin B12 following angioplasty. Some research suggests that it might decrease the risk of re-blockage of the blood vessels after balloon angioplasty. However, it does not seem to benefit people who had a tube (coronary stent) placed in the arteries.
    • Clogged arteries. Early research shows that taking vitamin B12, aged garlic extract, folic acid, vitamin B6, and L-arginine daily for 12 months slows the progression of clogged arteries and improves blood vessel function in people at risk for clogged arteries. The effect of vitamin B12 alone is not clear.
    • Eczema (atopic dermatitis). Early research shows that applying a vitamin B12 cream (Regividerm) to the affected area twice daily helps treat eczema.
    • Breast cancer. There is no evidence that dietary vitamin B12 alone reduces the risk of breast cancer. However, vitamin B12 may reduce the risk of breast cancer when taken with folate, vitamin B6, and methionine.
    • Canker sores. Early research shows that taking vitamin B12 1000 mcg under the tongue (sublingually) might help reduce the number of canker sore outbreaks, the duration of outbreaks, and pain caused by the canker sores.
    • Cervical cancer. Early research suggests that different forms of vitamin B12 taken together with a thiamine derivative (benfotiamine) and vitamin B6 might improve some symptoms of nerve pain associated with diabetes.
    • Colon and rectal cancer. Some population research suggests that people who consume more vitamin B12 in their diet have a lower risk of developing colon or rectal cancer. But early research shows that taking vitamin B12 with folic acid and vitamin B6 daily for up to 7.3 years does not reduce the risk of developing colorectal cancer in women.
    • Nerve damage caused by diabetes. Early research suggests that different forms of vitamin B12 taken together with a thiamine derivative (benfotiamine) and vitamin B6 might improve some symptoms of nerve damage associated with diabetes. Taking a specific medical food containing specific forms of vitamin B12, folic acid, and vitamin B6 also seems to have beneficial effects. Taking vitamin B12 alone by mouth or injected into the vein might help reduce pain but does not improve motor or sensory nerve function in people with nerve damage caused by diabetes.
    • Diarrhea. Early research suggests that taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk of diarrhea in children.
    • Fatigue. There is some evidence that receiving shots containing 5 mg of vitamin B12 in the form of hydroxocobalamin twice weekly might improve general well-being and happiness in people with fatigue.
    • Hepatitis C. Early research shows that giving an injection of vitamin B12 in the form of cyanocobalamin every 4 weeks along with standard care can improve hepatitis C treatment.
    • High triglyceride levels. Some evidence suggest that taking 7.5 mcg of vitamin B12 together with 5 grams of fish oil might be more effective then fish oil alone when used daily to reduce total cholesterol and triglyceride levels.
    • Lower respiratory tract infections. Early research suggests that taking twice the recommended daily allowance of vitamin B12, with or without folic acid, does not reduce the risk for lower respiratory tract infections in children.
    • Lung cancer. Early evidence suggests that there is no relationship between levels of vitamin B12 in the blood and the risk of lung cancer.
    • Nerve damage in the hands and feet (peripheral neuropathy). Early research shows that taking a specific product containing vitamin B12 (Keltican) daily for 60 days reduces pain by 44% and reduces the need for painkillers by over 75% in people with nerve damage in parts of the body such as the hands and feed.
    • Psoriasis. Early research shows that a specific cream containing vitamin B12 and avocado oil (Regividerm, Regeneratio Pharma AG) reduces symptoms of psoriasis as effectively as standard care and causes less irritation.
    • Schizophrenia. Early research shows that taking vitamin B12 with folic acid daily for 16 weeks can improve symptoms of schizophrenia related to abnormal emotions and behavior. But the treatment only seems to benefit some patients.
    • Shaky-leg syndrome. There are some reports that one form of vitamin B12 (cyanocobalamin) can help reduce tremors due to shaky-leg syndrome.
    • Blood clots in the veins. Population research suggests that having low levels of vitamin B12 might be linked to an increased risk for blood clots in the veins. But research evaluating the use of vitamin B12 to prevent blood clots in the veins is unclear.
    • Allergies.
    • Aging.
    • Chronic fatigue syndrome (CFS).
    • Diabetes.
    • Heart disease.
    • Lyme disease.
    • Immune system problems.
    • Memory problems.
    • Multiple sclerosis.
    • Other conditions.
    More evidence is needed to rate the effectiveness of vitamin B12 for these uses.


    VITAMIN B12 Side Effects & Safety

    Vitamin B12 is LIKELY SAFE for most people when taken by mouth, applied to the skin, taken through the nose, administered as a shot, or injected into the vein (by IV). Vitamin B12 is considered safe, even in large doses.

    Mild itching has been reported in one person who used a specific avocado oil plus vitamin B12 cream for psoriasis.

    Special Precautions & Warnings:

    Pregnancy and breast-feeding: Vitamin B12 is LIKELY SAFE for pregnant or breast-feeding women when taken by mouth in the amounts recommended. The recommended amount for pregnant women is 2.6 mcg per day. Breast-feeding women should take no more than 2.8 mcg per day. Don't take larger amounts. The safety of larger amounts is unknown.

    Post-surgical stent placement: Avoid using a combination of vitamin B12, folate, and vitamin B6 after receiving a coronary stent. This combination may increase the risk of blood vessel narrowing.

    Allergy or sensitivity to cobalt or cobalamin: Do not use vitamin B12 if you have this condition.

    Leber's disease, a hereditary eye disease: Do not take vitamin B12 if you have this disease. It can seriously harm the optic nerve, which might lead to blindness.

    Abnormal red blood cells (megaloblastic anemia): Megaloblastic anemia is sometimes corrected by treatment with vitamin B12. However, this can have very serious side effects. Don't attempt vitamin B12 therapy without close supervision by your healthcare provider.

    High numbers of red blood cells (polycythemia vera): The treatment of vitamin B12 deficiency can unmask the symptoms of polycythemia vera.

    VITAMIN B12 Interactions What is this?

    Major Interaction Do not take this combination

    • Chloramphenicol interacts with VITAMIN B12

      Vitamin B12 is important for producing new blood cells. Chloramphenicol might decrease new blood cells. Taking chloramphenicol for a long time might decrease the effects of vitamin B12 on new blood cells. But most people only take chloramphenicol for a short time so this interaction isn't a big problem.


    VITAMIN B12 Dosing

    The following doses have been studied in scientific research:

    ADULTS:

    BY MOUTH:

    • The typical general supplemental dose of vitamin B12 is 1-25 mcg per day: The recommended dietary allowances (RDAs) of vitamin B12 are: 1.8 mcg; older children and adults, 2.4 mcg; pregnant women, 2.6 mcg; and breast-feeding women, 2.8 mcg. Because 10% to 30% of older people do not absorb food-bound vitamin B12 efficiently, those over 50 years should meet the RDA by eating foods fortified with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 mcg per day has been used to maintain vitamin B12 levels in older people.
    • For vitamin B12 deficiency or pernicious anemia: cyanocobalamin doses of 300-10,000 mcg (microgram) daily have been used. However, some evidence suggests that the most effective oral dose is between 647-1032 mcg/day.
    • For high blood levels of homocysteine: vitamin B12 400-500 mcg in combination with 0.54-5 mg folic acid and 16.5 mg pyridoxine has been used.
    • For preventing age-related macular degeneration (AMD): vitamin B12 1 mg, folic acid 2.5 mg, and pyridoxine 50 mg daily has been used for 7.3 years.
    APPLIED TO THE SKIN:
    • For atopic dermatitis (eczema): a specific vitamin B12 0.07% cream (Regividerm) applied twice daily has been used.
    • For psoriasis: a specific cream (Regividerm, Regeneratio Pharma AG, Wuppertal, Germany) containing avocado oil plus vitamin B12 0.7 mg/gram applied for 12 weeks twice daily has been used.
    AS AN INJECTION:
    • For pernicious anemia: The FDA-approved dose of vitamin B12 for pernicious anemia is 100 mcg IM/SC once daily for 6-7 days. Then the dose may be given on alternate days for 7 doses followed by every 3-4 days for around 3 weeks. Thereafter, 100 mcg IM/SC should be given monthly for life.
    • For vitamin B12 deficiency: The usual dose is 30 mcg IM/SC daily for 5-10 days. For maintenance therapy, 100-200 mcg once monthly is commonly used. Both cyanocobalamin and hydroxocobalamin forms are used.
    • For a hereditary condition that causes vitamin B12 malabsorption (Imerslund-Grasbeck disease): vitamin B12 in the form of hydroxocobalamin has been injected into the muscle at a dose of 1 mg daily for 10 days followed by once monthly for the remainder of the person's life.
    • For cyanide poisoning: Hydroxocobalamin (Cyanokit) has been given intravenously (by IV) for a total dose of up to 10 grams.
    USED IN THE NOSE:
    • For pernicious anemia and vitamin B12 deficiency: Doses of 500 mcg of vitamin B12 have been injected into one nostril weekly.
    APPLIED UNDER THE SKIN:
    • For nerve damage from shingles: As an injection under the skin, 1000 mcg of vitamin B12, with or without 100 mg of thiamine, has been given six times weekly for 4 weeks.
    CHILDREN:

    BY MOUTH:
    • The recommended dietary allowances (RDAs) of vitamin B12 are: Infants 0-6 months, 0.4 mcg; infants 7-12 months, 0.5 mcg; children 1-3 years, 0.9 mcg; children 4-8 years, 1.2 mcg; children 9-13 years, and 1.8 mcg; older children.
    AS AN INJECTION:
    • For pernicious anemia: Vitamin B12 doses of 30-50 mcg IM/SC once daily for 2 or more weeks, up to a total dose of 1000-5000 mcg IM/SC, followed by 100 mcg IM/SC once every 4 weeks has been used.
    • For vitamin B12 deficiency: Vitamin B12 doses of 100 mcg IM/SC once daily for 10-15 days, followed by 60-100 mcg IM/SC once or twice weekly has been used for several months.

    See 131 Reviews for this Treatment - OR -

    Review this Treatment

    Learn about User Reviews and read IMPORTANT information about user generated content

    Conditions of Use and Important Information: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

    This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version. © Therapeutic Research Faculty 2009.

    Search for a Vitamin or Supplement

    Ex. Ginseng, Vitamin C, Depression

    Today on WebMD

    vitamin rich groceries
    Do you know your vitamin ABCs?
    St Johns wart
    Ease hot flashes and other symptoms.
     
    clams
    Are you getting enough?
    Take your medication
    Wonder pill or overkill?
     
    fruits and vegetables
    Video
    !!69X75_Vitamins_Supplements.jpg
    Article
     
    Woman sleeping
    Article
    Woman staring into space with coffee
    Article
     
    IMPORTANT: About This Section and Other User-Generated Content on WebMD

    The opinions expressed in WebMD User-generated content areas like communities, reviews, ratings, or blogs are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. User-generated content areas are not reviewed by a WebMD physician or any member of the WebMD editorial staff for accuracy, balance, objectivity, or any other reason except for compliance with our Terms and Conditions. Some of these opinions may contain information about treatment or uses of drug products that have not been approved by the U.S. Food and Drug Administration. WebMD does not endorse any specific product, service, or treatment.

    Do not consider WebMD User-generated content as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of something you have read on WebMD. You should always speak with your doctor before you start, stop, or change any prescribed part of your care plan or treatment. WebMD understands that reading individual, real-life experiences can be a helpful resource but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified health care provider. If you think you may have a medical emergency, call your doctor or dial 911 immediately.