Different handling for methyl vs cyano?

[Dopey-Grumpy-Sleepy]

I take cyanocobalamin that a doctor prescribes. It doesn't sting. I take methylcobalamin from a US supplier (made in Hong Kong) and it stings like a -- ! I know there is alcohol in the methylcobalamin. Is that because it doesn't hold up/travel as well as cyanocobalamin? I'm looking into getting methylcobalamin from a different source, but I'm wondering if all methylcobalamin is going to sting. It definitely doesn't make injection day any more pleasant!!!

[Gambit62 Administrator]

there are a large number of preservatives that can be used as stabilisers in injectable products like B12 - some people can react to them - trying a different brand with different preservatives may help

[fbirder]

Most methylcobalamin preparations contain benzyl alcohol as a preservative - empowerpharmacy.com/drugs/m... because it is less stabe than cyanocobalamin. That's also why it should be stored in refrigerator once it is in solution.

I guess that benzyl alcohol is one of the reasons why methylcobalamin injections aren't common in the EU. Because benzyl alcohol is harmful if swallowed or inhaled - echa.europa.eu/substance-in...