Vitamin B12 shots can help with a number of health issues, including: Energy levels: B12 shots can increase energy levels and combat fatigue Brain function: B12 shots can improve concentration and mood Metabolism: B12 shots can speed up metabolism Sleep patterns: B12 shots can help improve sleep quality Immune system: B12 shots can boost the immune system Hair loss: B12 shots can help with hair growth or stop hair loss Weight loss: B12 shots can help with weight loss Vision: B12 shots can help with blurred vision and age-related macular degeneration Bones: B12 shots can promote healthy bones and prevent osteoporosis A doctor may recommend B12 injections if you have a vitamin B12 deficiency. Symptoms of a deficiency include: Depression Difficulty walking Dizziness Irritability Loss of appetite Numbness and/or tingling