Q&A: B12 Shots

Question: Dr. Kiskila, what is a B12 shot and what does it do?

Answer: B12 is a water-soluble B complex vitamin that aids in the production of red blood cells. It’s a vitamin that helps treat anemia, helps to prevent or treat low vitamin B12 levels, helps metabolize fat and carbohydrates, and synthesizes protein. Your body doesn’t naturally make B12, so you get it from eating animal byproducts, or supplementing. 

Question: Who would benefit from a B12 shot?  Who should not get one?

Answer: Anyone with low vitamin B12 levels or who are immunocompromised may benefit from B12 injections. You should not get a B12 injection if you are allergic to cyanocobalamin (vitamin B12).  Ask your doctor if you are pregnant, or plan to become pregnant, or if you are breastfeeding before having a B12 shot.

Question: How long do the effects of a B12 shot last?  How often should you get them?

Answer: It depends on your vitamin B12 level and how fast your body absorbs vitamin B12. Typically B12 injections are administered on a monthly basis (up to 30 days vs. taking a daily supplement), but talk to your doctor to see how often is right for you. People who take a B12 injection may feel like they have more energy or have a higher metabolism.

Question: What are the negative side effects of a B12 injection?

Answer:  Most people have no or very minimal side effects from B12 injections, but some adverse reactions may be dizziness, headache, upset stomach, nervousness, or diarrhea.

Question:  How is a B12 shot different from getting B12 through dietary intake?

Answer:  B12 shots are the preferred method of administration, since dietary intake (oral route) has variable absorption rates.