Your doctor may prescribe vitamin B12 injections if you have low levels of B12 in your blood, a condition known as vitamin B12 deficiency. B12 deficiency can result if you don't eat enough of certain foods, particularly meat, poultry and seafood, or if you have an inability to absorb vitamin B12 from food. If your B12 absorption is impaired, you will need to receive injections more frequently than you will if your deficiency is a result of an inadequate diet. According to the Office of Dietary Supplements vitamin B12 is vital to the reaction that creates new DNA in your body. This function is particularly important in keeping your red blood cells healthy. With inadequate vitamin B12, your red blood cells can form incorrectly, leading to a condition known as megaloblastic anemia in which your red blood cells are swollen and ineffective. In addition to its role in DNA synthesis, vitamin B12 is necessary for the proper function of your nervous system. The daily recommended intake of vitamin B12 for adults is 2.4 mcg, and you can meet this need through supplementation or by eating a variety of animal products, including milk, meat and seafood.
Vitamin B12 deficiency occurs in 1.5 to 15 percent of the general public. According to a 2008 article in the journal "Blood," it may take 2 to 5 years for clinical symptoms of vitamin B12 deficiency to appear in people with malabsorption disorders such as pernicious anemia or sprue. If you don't eat meat, as in the case of a vegan diet, it may take more than 10 years before signs of deficiency appear. Deficiency is slow to develop because your body is able to store a large amount of vitamin B12 in the liver and other tissues. Symptoms of vitamin B12 deficiency include shakiness, inability to control bodily actions and neurological changes including psychosis or changes in mood. Doctors typically administer injections of vitamin B12 in doses of 1000 mcg. This amount of vitamin B12 corrects the physiological consequences of deficiency and also helps build up body stores of the vitamin. Of this 1000 mcg dose, your body retains approximately 150 mcg or roughly 15 percent. You retain a higher percentage of smaller doses, but the overall amount of vitamin B12 obtained from smaller doses is still less than that stored from a 1000-mcg injection.
Owing to your body's ability to store large amounts of vitamin B12, injections may be infrequent once your deficiency is resolved. If you cannot absorb vitamin B12 from food, Dr. Ralph Caramel, author of a 2008 article on vitamin B12 in the journal "Blood," suggests an initial injection cycle of 8 to 10 administrations over the first two to three months, then injections once a month thereafter. If you have low vitamin B12 levels that are due to improper intake, you will need fewer injections, provided you begin to eat foods rich in vitamin B12 more often. Always consult with your doctor or pharmacist regarding how often you should be receiving vitamin B12 injections. According to the Office of Dietary Supplements, overdosing on vitamin B12 is difficult and no known adverse health effects are associated with high vitamin B12 intakes from either food or supplements. Vitamin B12 can interact with certain medications, however. Check with your doctor or pharmacist about possible interactions these injections may have with other medications you are taking.
Though very rare, allergic reactions to vitamin B12 injections have occurred, and switching to an oral preparation of vitamin B12 may help prevent the reaction or reduce its severity. How to Take Vitamin B-12 at Night How Fast Will B-12 Work? Why Are the B12 Injections Not Working? Are There Advantages of Sublingual Vitamin B12? Does Sublingual B12 Really Work? Vitamin B12 by Subcutaneous Injection What Is the Normal Intramuscular Dose of Vitamin B12? Can You Get Vitamin B12 Anemia If You Had Your Gallbladder Removed? The Best Way to Take Vitamin B12 Supplements The Best Places to Give Vitamin B12 Injections How to Give B12 IM Injections Sublingual Vitamin B12 vs. Injectable B12 How is a B12 Injection Given? What Is Sublingual B12? Alcohol's Effects on B-12 Absorption Taking Vitamins With Food Vs. When Will I Feel Better With B12? The Best-Absorbed B12 Supplement How to Test for Vitamin and Mineral Deficiencies
Taking B6 & B12 to Lose WeightThe below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.Recommended dietary amounts (RDAs) are 2.4 micrograms daily for ages 14 years and older, 2.6 micrograms daily for pregnant females, and 2.8 micrograms daily for breastfeeding females. Those over 50 years of age should meet the RDA by eating foods reinforced with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 micrograms daily has been used to maintain vitamin B12 levels in older people. A doctor and a pharmacist should be consulted for use in other indications. For canker sores, sublingual (under the tongue) vitamin B12 has been given daily for six months.
For claudication, a total daily dose of 1.5 milligrams of vitamin B12 was taken by mouth in divided doses of 0.5 miligrams three times daily for six months. For vitamin B12 deficiency, 125-2,000 micrograms of cyanocobalamin has been taken by mouth daily for up to 2.5 years or longer. Five hundred micrograms of sublingual (under the tongue) vitamin B12 has been used daily for up to four weeks. The following doses have been given intravenously (through the veins): 1,000 micrograms of intramuscular cobalamin once daily for 10 days (after 10 days, the dose was changed to once weekly for four weeks, followed by once monthly for life); 1,000 micrograms of intramuscular cyanocobalamin given on days 1, 3, 7, 10, 14, 21, 30, 60, and 90 of treatment. For vitamin B12 deficiency caused by long-term PPI therapy, cyanocobalamin nasal spray has been used for eight weeks. The exact dosage is unclear. One study tested intranasal vitamin B12 replacement therapy (500 micrograms weekly). For prevention of anemia, the following doses have been taken by mouth: 2-10 micrograms of vitamin B12 daily combined with iron and/or folic acid for up to 16 weeks;
100 micrograms of vitamin B12 every other week plus daily folic acid and/or iron for up to 12 weeks. For mental performance, the following doses have been taken by mouth: 0.05-1 milligram vitamin B12 taken daily for four weeks to 5.4 years; 10 micrograms or 50 micrograms of cyanocobalamin daily for one month; and one milligram of cyanocobalamin weekly for four weeks. One 1,000 microgram vitamin B12 injection has been used daily for five days, followed by one 1,000 microgram injection monthly for five months. Additionally, 1000 microgram injections have been used weekly for four weeks or monthly for six months. For cyanide poisoning, an intravenous (IV) infusion of five grams of hydroxocobalamin (up to 20 grams) has been used. For depression, one milligram of cyanocobalamin, through intramuscular injections, was used weekly for four weeks. For hereditary sideroblastic anemia, 100 micrograms of intramuscular vitamin B12 has been used monthly, with or without daily folic acid, for up to four months.