syringe needle for vitamin b12 injections Red Liquid in a Disposable with a and in a Glass Ampoule on a White Background. Stock Image B12 Injections for Energy: Benefits

If you bought it from a UK supplier then it's much more likely that your they have had them stored at room temperature for days/weeks/months

Phase 2 trials used subcutaneous 1 mg/day

doi:10.1038/s41586-020-2639-4

These may include but are not limited to: Redness and/or swelling to the treated area Temporary heaviness or tenderness in the arm Excess supplementation is possible if not clinically required, which is why medical consultation and monitoring are essential

5-mTHF is demethylated to complete the folate cycle by donating a carbon into the methionine cycle through the methylation of homocysteine (hCYS) by methionine synthase and its cofactor vitamin B12 (B12)