B12 shots are generally administered to correct or prevent a vitamin B12 deficiency, states WebMD. It is commonly used in people with pernicious anemia, a serious type of anemia seen mainly in older patients.
Vitamin B12 supplementation may be given for other conditions, such as memory loss, Alzheimer's disease, heart disease, diabetes, depression and asthma, states WebMD. It helps to boost the immune system, mood and energy levels.
Individuals with Leber's disease should not take B12 because it can lead to optic nerve damage and blindness, states Drugs.com. Doctors don't know if the injection will affect an unborn baby, but it will pass into breast milk. Pregnant or nursing women should consult a doctor before receiving the medication.
Vitamin B12 shots may be given at home and are injected under the skin or into the muscle, states Drugs.com. Patients should discard each syringe after use into a sharps disposable container. Contact a local pharmacist to learn how to properly dispose of needles in your area.
Some people may experience an allergic reaction to a vitamin B12 shot that requires medical attention. Symptoms might include hives, swelling of the facial area and difficulty breathing, advises Drugs.com. Patients should also contact a doctor if they experience numbness in the hands and feet, confusion, extreme thirst, muscle weakness or coughing up foamy mucus.