Vitamin B12 injections are used to treat pernicious anemia, which is caused by vitamin B12 deficiency, according to Drugs.com. Vitamin B12 is a water-soluble B-complex vitamin that is necessary for the production of red blood cells, DNA synthesis and the maintenance of healthy nerve cells. Dietary sources of vitamin B12 include animal products such as eggs, fish, shell fish, poultry and meat. Vitamin B12 is not found in plants.
Pernicious Anemia
Pernicious anemia is a lack of enough healthy red blood cells caused by a deficiency of vitamin B12, according to the National Heart Lung and Blood Institute. Deficiency of vitamin B12 is mainly caused by problems with absorption of the vitamin because of lack of intrinsic factor, a protein found in the stomach that enables the body to absorb vitamin B12 from food and supplements. Patients who have parts of their stomach and intestines removed are at high risk for pernicious anemia because the sources of intrinsic factor are removed during surgery. Vegetarians also are at high risk for pernicious anemia because vitamin B12 is found naturally only in animal products such as meat, fish, poultry and shellfish.
Symptoms of Pernicious Anemia
Classic symptoms of pernicious anemia include fatigue and shortness of breath because the body does not have enough red blood cells to oxygenate the tissues, according to the National Heart, Lung and Blood Institute. Other symptoms of pernicious anemia include smooth tongue, rapid heart rate, tingling and numbness in hands and feet, bleeding gums, diarrhea, loss of appetite, mood changes, unsteady gait and sore mouth.
Administration of Vitamin B12 Injections
Pernicious anemia is treated with vitamin B12 injections, according to the National Heart, Lung and Blood Institute. B12 is administered as a deep intramuscular injection so that the vitamin is absorbed directly into the blood stream. Oral forms of B12 supplements are not recommended for the treatment of pernicious anemia because of problems with absorption caused by lack of intrinsic factor. B12 injections for severe anemia are administered daily at the doctor's office. Patients who show improvement in symptoms might receive monthly injections.
Side Effects of B12 Injections
Patients receiving vitamin B12 injections might experience side effects such as pain, redness and swelling at the injection site. Patients who notice unusual warmness and foul discharge at injection site should consult the doctor, as this is a sign of infection. Others might experience adverse symptoms such as blood clots, hives, problems breathing and sudden weight gain. Patients who notice these adverse symptoms should seek immediate medical attention because these are the symptoms of problems with the cardiovascular system caused by vitamin B12.
Complications of Pernicious Anemia
Patients who fail to receive treatments for pernicious anemia eventually develop neurological damage and neurological defects of the brain and spine, according to the National Heart Lung and Blood Institute. Untreated pernicious anemia also can cause damage to vital organs such as the heart, kidneys and brain because of the lack of flow of oxygenated blood to these organs.
