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Methylcobalamin is the form most people reach for in a sublingual or spray. These are the questions our team asks before recommending it.

A good fit if

• You want a sublingual, spray or drop rather than a tablet to swallow
• You're vegan or vegetarian and want the coenzyme form of B12
• You've had gastric bypass surgery and need an oral option that matched injections in a trial
• Your practitioner has suggested this form specifically, alongside your usual care

Check with us first if

• You're on metformin long-term. It lowers B12 the longer you take it, and the risk rises with years of use.
• You take a high-dose folate or folic acid supplement. Large folate doses can make your blood test look normal while nerve damage carries on.
• You use nitrous oxide, medically or recreationally. It inactivates B12, and a normal blood test won't pick it up.
• You take a proton pump inhibitor or another reflux medicine long-term.
• You're pregnant or breastfeeding. Talk to your doctor before starting, especially in the first trimester.
• You take any prescription medicine at all. Check with your doctor, pharmacist or our naturopaths first.

Reference values. The NHMRC recommended daily intake for vitamin B12 is 2.4 µg a day for adults, rising to 2.6 µg in pregnancy and 2.8 µg while breastfeeding. Those figures are for the vitamin as a whole, not this form specifically. You'll find the full table by age on our vitamin B12 page.

Typical supplemental range. Australian sublinguals, sprays and drops commonly contain 500 to 1,000 µg of methylcobalamin, and some sublinguals go up to 5,000 µg. The trials used 1,000 µg a day, swallowed or taken under the tongue, in people who were low in B12, had trouble absorbing it or were managing diabetes.

Upper level. The NHMRC hasn't set an upper limit for vitamin B12 in any form. In its own words: "There are insufficient data to allow setting of a UL." Australian rules set no dose cap for mecobalamin either, only the condition that it's for oral use.

Worth knowing. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Meat, fish and shellfish: the main dietary sources; the B12 in food is a mix of forms your body converts, including into methylcobalamin
• Liver: the most concentrated source, though only about 11% of its B12 is actually absorbed
• Eggs and trout: 24 to 40% of the B12 present is absorbed
• Mutton and chicken: more than 60% of the B12 present is absorbed, the highest rate measured
• Milk and dairy: about 30% of adult intake and 50% of children's intake comes from here

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• You're sensitive to cobalt or vitamin B12. Allergic reactions, including anaphylaxis, have been reported with cobalamin treatment.
• You've taken metformin long term. It lowers B12 the longer you take it, and the risk rises with years of use.
• You take high-dose folate or folic acid as well. It can correct blood-count changes while nerve damage carries on unnoticed.
• You use nitrous oxide, medically or recreationally. It knocks out B12, and a normal blood test won't pick it up.
• You've used proton pump inhibitors or reflux medicine long term.
• You're pregnant or breastfeeding. Talk to your doctor first, especially in the first trimester.
• You have ongoing nerve symptoms like numbness, tingling, unsteadiness or memory changes. These need a diagnosis, not a supplement.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.