giving a b12 injection How to self-inject intramuscular vitamin - Overview Treating Severe Vitamin B12 Deficiency

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John DiBella Published: November 3, 2025 Fact-checked by Dr

There are some nerves running through the shoulder and there is always a slight chance a needle may hit a nerve if the injection location is incorrect

People with symptoms of vitamin B12 deficiency It is a good idea for anyone with the following signs and symptoms of a vitamin B12 deficiency or pernicious anemia to consult a doctor: People with gastrointestinal issues Conditions that affect the gastrointestinal tract may affect vitamin B12 release or absorption, including: 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 diabetes thyroid disease Crohns disease celiac disease chronic pancreatitis People who have undergone gastrointestinal surgery, including weight loss, may have fewer cells necessary to secrete stomach acid and intrinsic factor

This is particularly true for those following a vegetarian or vegan diet