Vitamin B12 shots are injections that a doctor may prescribe to treat a vitamin B12 deficiency. They may be useful for those with gastrointestinal issues, older adults, and vegans and vegetarians.
A deficiency in vitamin B12 can lead to various health problems, ranging from fatigue to permanent neurological changes.
If a person has low vitamin B12 levels due to a health condition, a doctor may recommend oral supplementation or injections of the vitamin.
Injections are usually for people with bodies that have problems absorbing vitamin B12 and those who have undergone gastric surgery. This is because shots enable the body to absorb vitamin B12 without it having to go through the digestive system.
This article addresses the importance of maintaining adequate vitamin B12 levels and outlines the benefits and risks associated with vitamin B12 shots.
Vitamin B12 is an essential water-soluble vitamin that plays a role in many bodily functions, including:
- DNA production
- red blood cells
- nerve cells
Without vitamin B12, a person may start to feel tired and weak due to megaloblastic anemia.
Vitamin B12 is present in
- meat
- fish
- eggs
- dairy products
- nutritional yeast
- some fortified foods
In animal-based foods, vitamin B12 binds to the protein molecules. During digestion, stomach acid causes it to separate from the protein, and a substance called intrinsic factor enables the bloodstream to absorb it.
Some people’s bodies do not produce enough stomach acid or intrinsic factor if they have a condition known as autoimmune atrophic gastritis. These people may need vitamin B12 shots to reduce their risk of deficiency, which can lead to pernicious anemia.
Other people who may needs shots include those who have had gastrointestinal surgery if their digestive system cannot absorb vitamin B12 efficiently.
The table below contains the
| Group | Amount |
| 0–6 months | 0.4 micrograms (mcg) |
| 7–12 months | 0.5 mcg |
| 1–3 years | 0.9 mcg |
| 4–8 years | 1.2 mcg |
| 9–13 years | 1.8 mcg |
| 14+ years | 2.4 mcg |
| Pregnant people | 2.6 mcg |
| People who breastfeed | 2.8 mcg |
However, a doctor can advise on an individual’s specific needs.
Vitamin B12 shots are a form of supplementation that contains a synthetic version of vitamin B12, or cyanocobalamin.
A doctor will inject the shot into the muscle. If they inject it into a vein, the body may lose a high proportion as the person passes urine.
Cyanocobalamin is available in liquid, tablet, and capsule form. Certain foods, such as cereals, may be fortified with the synthetic form of vitamin B12.
Vitamin B12 shots are only available by prescription following a clinical diagnosis of low levels. However, low levels
That said, some people have a higher risk of deficiency and may benefit from vitamin B12 shots or tablets.
People with symptoms of vitamin B12 deficiency
Anyone who has signs and symptoms of a vitamin B12 deficiency or pernicious anemia should consult a doctor.
Signs and symptoms include:
- difficulty thinking and remembering
- fatigue
- heart palpitations
- pale skin
- weight loss
- infertility
- numbness and tingling in the hands and feet
- dementia
- mood changes
- a sore tongue
- low appetite
- constipation
Vitamin B12 deficiency risk factors
The following risk factors can increase the chance of developing vitamin B12 deficiency:
- high alcohol consumption
- older age
- pernicious anemia
- atrophic gastritis, which refers to inflammation in the stomach
- Helicobacter pylori infection
- celiac disease
- Crohn’s disease
- a history of gastrointestinal surgery
- following a plant-based diet
- pancreatic insufficiency
- AIDS
- some hereditary conditions that affect vitamin B12 absorption
People with gastrointestinal issues
Conditions that affect the gastrointestinal tract may affect vitamin B12 release or absorption.
- pernicious anemia, which can lead to gastric atrophy, or damage to the stomach
- fish tapeworm infestation
- bowel or pancreatic cancer
- folic acid deficiency
- overgrowth of bacteria in the small intestine
- celiac disease
- Crohn’s disease
Individuals who have undergone gastrointestinal surgery, including weight loss surgery, may have fewer of the cells necessary to secrete stomach acid and intrinsic factor. This can also affect vitamin B12 absorption.
Older adults
The scientists found that older adults have a higher risk of conditions linked to reduced stomach acid production, including gastric atrophy. Low stomach acid also enables certain bacteria to grow, and these can use up vitamin B12 stores.
Vegetarians and vegans
Vitamin B12 mainly occurs in animal foods, so people who follow a plant-based diet have a higher risk of vitamin B12 deficiency.
Vegetarian or vegan people who are pregnant may
In rare cases, a doctor may recommend injections, but
A doctor may recommend vitamin B12 shots for people who are at risk of a deficiency or its complications.
Vitamin B12 shots may help reduce the risk of the following conditions:
- heart disease
- stroke
- neurological disorders
- problems with thinking and memory
- vision loss
- infertility
- neural tube defects in children born to those with a vitamin B12 deficiency
There is no upper limit for the intake of vitamin B12 because the risk of toxicity or overdose is low. However, vitamin B12 shots may have other side effects.
If a person experiences the following, or if these issues persist or worsen, they should seek medical advice:
- pain, redness, or itching at the site of the injection
- mild diarrhea
- a swelling sensation in the body
- temporary itching of the skin
There may also be a risk of:
- anaphylaxis
- pulmonary edema
- congestive heart failure
- peripheral vascular thrombosis, which involves blood clots
- polycythemia vera, which is a type of blood cancer
If anyone experiences difficulty breathing, hives, and swelling, they need emergency medical help. They may be experiencing anaphylaxis, which is a severe allergic reaction.
Drug interactions
Vitamin B12
Some commonly prescribed medications that may interact with vitamin B12 include:
- H2 receptor antagonists
- metformin
- proton pump inhibitors
Allergies and medical conditions
Those who have allergies or medical conditions should always inform a doctor before receiving a vitamin B12 shot.
Vitamin B12 shots may not be suitable for people with a history of:
- sensitivity to vitamin B12
- Leber’s disease, which affects the optic nerve
- kidney problems
- hypokalemia, or low potassium levels
- deficiencies in other nutrients, particularly folic acid and iron
Most people get enough vitamin B12 from their diet, but some people have a deficiency. This can be due to having low levels of intrinsic factor in the digestive system, having a digestive condition, or following a plant-based diet.
The
If dietary sources are insufficient, however, a doctor may recommend supplementation through pills or injections, depending on the cause of the deficiency.