The Best Places to Give Vitamin B12 Injections

Vitamin B12 injections are a great way to get B12 for those who don't get enough.
Image Credit: Christian Buch/iStock/GettyImages

Vitamin B-12 injections can be a helpful alternative to vitamin B-12 supplements for those who experience a deficiency but struggle to get enough of the vitamin through consumption of B-12 rich foods or from tablets and capsules.


Vitamin B-12 shots are usually administered as intramuscular injections, meaning the best B-12 injection sites are predominantly anywhere that muscle is abundant. Therefore, vitamin B-12 injection sites include the upper arms, buttocks and thigh area. They are usually given by a health care professional in a clinic or office.

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Read more: 4 Reasons Your B Vitamin Injections Might Not be Working


Vitamin B-12 Injections

Vitamin B-12 injections are most commonly used to treat vitamin B-12 deficiency anemia. This is when the body, for various reasons, is not receiving enough vitamin B-12.

The cause could be dietary choices (such as with vegans and vegetarians, because B-12 is mostly found in animal products) or issues with the intestines' ability to absorb vitamins. The deficiency results in abnormally large blood cells that don't function properly.


According to the National Health Service of the United Kingdom, symptoms of vitamin B-12 deficiency include extreme tiredness, breathlessness, headaches, pale skin and loss of appetite.

There are two types of vitamin B-12 injections, which come in the form of:

  • Hydroxocobalamin
  • Cyanocobalamin


Hydroxocobalamin is recommended more often than cyanocobalamin because it remains in the system for longer, so fewer injections are required over time.

How Are B-12 Shots Administered?

Administered intramuscularly, B-12 shots are absorbed slowly from the site of the injection into the body's natural stores. Initially, someone requiring B-12 shots receives them every two to three days for two weeks; following this, the shots are administered once every two to three months.


This is due to the slow absorption of vitamin B-12 injections over time, particularly hydroxocobalamin over cyanocobalamin. So once the body has stored up enough vitamin B-12, the injections can usually be reduced because the body will naturally hold enough.


Read more: What Is the Normal Intramuscular Dose of Vitamin B12

Vitamin B-12 Injection Sites

Vitamin B-12 shots can be administered in various sites on the body, and the location can vary based upon patient age, health and whether or not the B-12 shots will be self-administered.


Vitamin Injections advises the following as appropriate B-12 injection sites:

Upper arm: Recommended primarily for adolescents and young to middle-age adults, the deltoid muscle in the upper arm is an ideal location for vitamin B-12 injections. By adolescence, it is developed enough to have the necessary thickness intramuscular injections require. Should the muscle remain well developed into later adulthood, older adults can also have intramuscular injections administered here.


Thigh: Specifically, the muscle injected is known as the vastus lateralis muscle. The thigh is a strong muscle appropriate for vitamin B-12 injections, and it is most appropriate for newborns and infants because it is one of the most developed muscles in youth. The thigh can also be appropriate for adults because it's so easy to self-administer injections there. The needle is usually 2.5 centimeters in length and is inserted at a 90-degree angle.


Only self-administer medication of any type if you're advised to do so by a health care professional. Always consult your usual health care professional before beginning any new medications.

Outer hip: Also known as the ventrogluteal injection site, this spot is most appropriate for adults and for infants above the age of seven months. Located just above the hip joint, it's an ideal location for B-12 shots because it is free of the potential complications of other B-12 injection sites. These may arise from damage to major blood vessels or to nerves, but neither are worries when you inject in the outer hip.


Buttocks: The buttocks, or the dorsogluteal region, used to be a popular injection site but has recently become more of a last resort, because it's so close to the sciatic nerve and to some major blood vessels. In addition, because of the thick layer of adipose tissue — aka fatty tissue — in this region, the uptake of vitamin supplementation by the body is slower than you'll find in other B-12 injection sites.


Benefits of B-12 Shots

Vitamin B-12 injections are predominantly used to treat vitamin B12 deficiency. The most common of these is pernicious anemia, a condition in which the body cannot absorb vitamin B-12 sufficiently from diet or capsules because of a problem with the digestive system.

This can be counteracted by regular injections of either hydroxocobalamin or cyanocobalamin.


Hydroxocobalamin must not be administered to anyone who is pregnant or breastfeeding, because it can be potentially damaging to newborns. Always contact your health care professional before considering these injections.

Symptoms of deficiency are usually subtle and sometimes entirely imperceptible, but several have been attributed to a vitamin B-12 deficiency:

  • Weakness: A lack of strength when lifting or engaging in activities that usually would require no excessive exertion
  • Fatigue: Persistent tiredness
  • Tingling or numbness: Particularly in the hands and feet
  • Pale skin: A loss of color in the skin, which can also appear faintly yellow
  • Fast heartbeat: Inability to maintain a normal heartbeat despite resting
  • Shortness of breath
  • Bloating or gas
  • Constipation or diarrhea
  • Loss of appetite
  • Depression: Vitamin B-12 is linked with mental ability, so a sustained deficiency can ultimately have a detrimental effect on the brain
  • Dementia: A persistent lack of vitamin B-12 can, over time, damage mental agility and can potentially lead to dementia.

So, arguably, the greatest benefit of B-12 shots is offsetting of any of the above symptoms of vitamin B-12 deficiency. However, there are other potential benefits associated with an increased intake of B-12 through injection.

Thanks to its role in the health of the nervous system and red blood cell production, the overall health benefits of increased B-12 shouldn't be ignored even if you don't have a deficiency. The Mayo Clinic advises that increased levels of B-12 paired with higher intakes of vitamins B-6 and B-9 actually reduces the amount of homocysteine — which can contribute to heart disease — in the blood.

However, it is important to note that despite the benefits associated with vitamin B-12, there is no significant clinical evidence proving its role in specifically fighting heart disease.

Prescription B-12 Injections

Vitamin B-12 injections are usually provided by prescription as opposed to being store bought like the more conventional capsule supplements. This is because B-12 shots are usually only used in instances when the deficiency is so severe that you need to go beyond making dietary alterations.


If you recognize any of the listed symptoms in yourself, contact your health care professional and request advice on whether you have a vitamin B-12 deficiency.




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