Safety and side effects

When taken at recommended doses, vitamin B-12 supplements are generally considered safe. The recommended daily amount of vitamin B-12 for adults is 2.4 mcg and 10 to 12 mcg for older adults.

Taking doses of vitamin B-12 might cause:

• Headache.
• Nausea.
• Diarrhea.
• Weakness.
• Tingling sensation in hands and feet.

Having vitamin B-12 levels that are too high may raise the risk of getting cancer or breaking a hip.