Methylcobalamin vs Cyanocobalamin

For most people both correct a B12 deficiency equally well. Methylcobalamin is the active form and avoids the trace cyanide in cyanocobalamin, which is why it is often preferred; cyanocobalamin is cheaper and more stable. Choose methyl for the body-ready form, cyano for the cheapest proven option.

No. The amount is minute and the body clears it easily, and cyanocobalamin has a long safety record. Some people still prefer methylcobalamin simply to avoid it entirely.

The cheapest Methylcobalamin we track is $0.05 per serving; the cheapest Cyanocobalamin is $0.04 per serving — so Cyanocobalamin costs less per dose right now (August 2026).

For most people, cyanocobalamin and methylcobalamin are both absorbed well from supplements, and the dose you actually take matters more than the form. Some small studies suggest methylcobalamin may be retained a little longer in the body (cyanocobalamin tends to be cleared in urine more readily), but both reliably raise B12 levels. Cyanocobalamin is usually cheaper per dose, so it is often the better value for simply correcting a low B12 level. Anyone with a known absorption problem (such as pernicious anemia or after gastric surgery) should ask a clinician about higher doses or injections.

Some people with MTHFR gene variants prefer methylcobalamin, the already-methylated form, on the idea that their bodies handle synthetic B12 less efficiently. It is worth being clear that there is little solid evidence methylcobalamin is actually better for people with these variants, and many do perfectly well on cyanocobalamin (MTHFR mainly affects how the body processes folate, not B12). If you still want the methylated form, know that it usually costs more per dose, so comparing prices helps. Because this involves a genetic result, it is reasonable to discuss it with a clinician before building a routine around it.

The main practical downsides of methylcobalamin are that it is less stable than cyanocobalamin (more sensitive to light) and usually costs more per dose, so you are often paying a premium for the active form. Side effects are uncommon with either form but can include mild nausea, headache, or diarrhea. If your goal is simply raising a low B12 level, the cheaper cyanocobalamin often works just as well. Methylcobalamin's possible edge is mostly discussed for neurological support, where the evidence is still limited.

Most people have no reason to avoid cyanocobalamin. It is widely used, very stable, and the trace cyanide it contains is far too small to be harmful for healthy people. The usual reasons someone picks methylcobalamin instead are a preference for the ready-to-use form, possibly better retention, or specific situations such as impaired kidney function or certain rare conditions, where a clinician may suggest a different form. For routine supplementing on a budget, cyanocobalamin remains a cheap, effective option. Ask a healthcare provider if a specific medical situation applies to you.

The RDA for adults 19+ is 2.4 mcg daily; 2.6 mcg in pregnancy and 2.8 mcg during lactation. Adolescents 14-18 also need 2.4 mcg. Younger children need 0.9-1.8 mcg. Infants have an Adequate Intake of 0.4 mcg (0-6 months) and 0.5 mcg (7-12 months). — per the NIH Office of Dietary Supplements; general information, not medical advice.

The Food and Nutrition Board did not establish a Tolerable Upper Intake Level (UL) for vitamin B12 because of its low potential for toxicity. Even at large doses, vitamin B12 is generally considered safe because the body does not store excess amounts. — per the NIH Office of Dietary Supplements; general information, not medical advice.