Vitamin B12 injections can help boost your body’s energy levels by preventing fatigue. It is also essential for the health of your skin, hair and nails. Its other benefits include boosting your brainpower by slowing down memory loss, alleviating anxiety and aiding sleep. Vitamin B12 injections are the most effective when taken at regular intervals. It’s recommended once weekly for 6 weeks, followed by one every 6 weeks.