Gold Member Badge


  • You're all caught up!

The Side Effects of Too Much Vitamin B12

author image Megan Smith
I am a fast and efficient writer that would love to write articles for your company. Thank you for your consideration!
The Side Effects of Too Much Vitamin B12
A patient speaking to a doctor in office. Photo Credit: Plush Studios/Blend Images/Getty Images

Vitamin B12 is a vitamin that is essential to human life. It is found naturally in foods like fish, meat and dairy products. It can also be taken as a supplement, either injected, in caplet form or as a gel that is absorbed through the nose or mouth. The recommended dosage of for adults is 2.4 micrograms of vitamin B12 per day. Before taking supplements, discuss their use with your doctor to avoid potential risks and side effects.

Video of the Day

Cardiovascular Effects

When vitamin B12 is injected into the body, side effects can occur in the cardiovascular system, which carries blood to and from the heart. Serious side effects including congestive heart failure; peripheral vascular thrombosis, when a clot forms in a blood vessel; or pulmonary edema, when air sacs form in the lungs. These conditions may occur in patients who take more than the recommended dosage of the nutrient intravenously. Symptoms of these conditions include shortness of breath, pain in the arms or legs, and numbness in the arms.

Dermatological Effects

If you put too much vitamin B12 in your nasal cavity for absorption or inject it into the body, you may have dermatological side effects. Mild to severe acne may occur especially on the face, and folliculitis may occur. If you are experiencing more acne than usual, lower your dose; if the acne derives from the supplement, it should clear up within 10 days. Supplemental vitamin B12 has also been associated with severe rosacea flareups, as well as milder symptoms, like itchy skin or light rashes on the body and face.

Other Effects

Other side effects due to taking too much vitamin B12 include headache, dizziness, diarrhea, indigestion, upset stomach, vomiting, nausea, back pain, swelling, arthritis, anxiety, nervousness and lack of coordination. Report any of these side effects to your doctor.

Risk of Contaminants

A vitamin B12 supplement does contain the essential vitamin necessary for your body, but it also may contain other additives, including iodine and sorbitol, that your body may have a reaction to. Too much iodine can cause a number of reactions, including digestive upset and a burning sensation in your mouth, while sortbitol can cause allergic reactions, dry mouth and blood in your stool. Report any of these side effects to your doctor.

LiveStrong Calorie Tracker
Lose Weight. Feel Great! Change your life with MyPlate by LIVESTRONG.COM
  • Gain 2 pounds per week
  • Gain 1.5 pounds per week
  • Gain 1 pound per week
  • Gain 0.5 pound per week
  • Maintain my current weight
  • Lose 0.5 pound per week
  • Lose 1 pound per week
  • Lose 1.5 pounds per week
  • Lose 2 pounds per week
  • Female
  • Male
ft. in.



Demand Media