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No tolerable upper intake level (UL) has been set for vitamin B12. The National Academies found too little data to set one for vitamin B12. Health Canada, which uses the same values, adds that this "does not mean that there is no potential for adverse effects resulting from high intakes." That doesn’t make any amount safe for everyone: talk to your doctor about high doses.
Take several supplements? Add them all up in the Supplement Checker: it shows your vitamin B12 total next to the nutrients that do have a limit.
How much Vitamin B12 you need
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | 0.4 mcg* | 0.4 mcg* | – | – |
| 7-12 months | 0.5 mcg* | 0.5 mcg* | – | – |
| 1-3 years | 0.9 mcg | 0.9 mcg | – | – |
| 4-8 years | 1.2 mcg | 1.2 mcg | – | – |
| 9-13 years | 1.8 mcg | 1.8 mcg | – | – |
| 14-18 years | 2.4 mcg | 2.4 mcg | 2.6 mcg | 2.8 mcg |
| 19-30 years | 2.4 mcg | 2.4 mcg | 2.6 mcg | 2.8 mcg |
| 31-50 years | 2.4 mcg | 2.4 mcg | 2.6 mcg | 2.8 mcg |
| 51-70 years | 2.4 mcg | 2.4 mcg | – | – |
| 71+ years | 2.4 mcg | 2.4 mcg | – | – |
* Adequate Intake (AI): the amount set when there isn’t enough evidence for an RDA.
What counts toward the Vitamin B12 limit
No upper limit (UL) has been set for vitamin B12.
What happens with too much Vitamin B12
The National Academies' 1998 DRI report says "No adverse effects have been associated with excess B12 intake from food or supplements in healthy individuals", but the evidence was not sufficient to set a UL. Health Canada's DRI table adds that the lack of a UL "does not mean that there is no potential for adverse effects resulting from high intakes."
Sources: Health Canada, Dietary Reference Intakes tables (the joint U.S.-Canada values); National Academies, Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998); National Academies, Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998). Limits checked November 8, 2026. More from the NIH: Office of Dietary Supplements Vitamin B12 fact sheet.
If you think you or a child took too much of a supplement, call Poison Control at 1-800-222-1222 (U.S., free, 24 hours) or use poison.org. In an emergency, call 911.
General information, not medical advice. Your doctor may recommend a different amount, for example to treat a deficiency. Talk to your doctor or pharmacist before you start, stop or change a supplement, especially if you are pregnant, nursing, take medication or have a medical condition.