Potential effects on reproductive health with chronic use are unstudied
doi: 10.3390/biomedicines12112632 105 PapademetrioDLTrabucchiACavaliereVRiccoRCostantinoSWagnerMLet al

It includes 1-5 intramuscular or subcutaneous injections of 1000 mcg crystalline cyanocobalamin daily, followed by oral doses of 1000-2000 mcg/day Parenteral administration should be reserved for those with significant neurological symptoms NICE guideline: Vitamin B 12 deficiency in over 16s: diagnosis and management: Malabsorption as the confirmed or suspected cause of vitamin B 12 deficiency: Offer replacement to people if: lifelong intramuscular vitamin B12 Autoimmune gastritis is the cause They have had a total gastrectomy They have had a complete terminal ileal resection If the person has a vitamin B 12 deficiency because of malabsorption that is not caused by autoimmune gastritis, or a total gastrectomy or complete terminal ileal resection (for example, malabsorption caused by coeliac disease, partial gastrectomy or some forms of bariatric surgery): Offer vitamin B 12 replacement and Consider intramuscular instead of

Acute injuries typically respond faster than chronic degenerative conditions
And the grey literature that biohackers treat as scientific authority, such as vendor blogs, wellness clinic testimonials, and podcast conversations between non-researchers, is not remotely equivalent to peer-reviewed evidence
Before departing, identify which day of the week works best for your trip itinerarychoosing a day when you'll be at your accommodation with access to refrigeration and a calm injection environment