Vitamin B12 injections are most commonly prescribed to prevent a deficiency or treat a B12 deficiency in people who have an impaired ability to absorb this crucial nutrient. The injection contains about 500 times more vitamin B12 than the recommended daily dose. Injecting B12 allows the vitamin to be delivered directly to the bloodstream so that it is easily absorbed by the body.
Vitamin B12 plays a key role in the normal functioning of the brain and nervous system, and in the formation of healthy blood cells. Although most people get enough Vitamin B12 from a healthy diet, some individuals have difficulty absorbing this essential nutrient. An ongoing B12 deficiency can damage the nervous system, and even less severe cases still result in a range of unpleasant symptoms including tiredness, weakness, constipation, loss of appetite, weight loss, problems with balance, depression, poor memory, and soreness of the mouth or tongue.