Yeah B-12 injections work much better than capsules in my opinion...second best would be the sublingual B12 tablets (Methylcolbamin )sp?
Make sure you drink a full 1.5 litres or so of water right after for better absorption, to avoid dehydration or any other side effects.
I get them every other month or so alternated with IV vitamin therapy suited to my biochemistry. Started doing it just before the pandemic hit for health reasons and haven't stopped.
I use the ones by nature made but any should work. When you first start using them, take them after you wake up. If I took them too late in the day that energy boost kept me up half the night. B vitamins are water soluble so anything you can't use at the time, the body will excrete. Having sustained release helps space that out.
I'm working a split shift now so I just bought a whole food b vitamin that I'm trying out. It's not time released and the dosage is 2 pills, so I take one at the beginning of each shift. It doesn't have the noticeable effect of the time released, but the daily allowance may be lower also.
Been suffering from being lethargic for a while even with exercises and eating good but after taking Vit B12 wifey's advice, the situation improved. Used to doze off during meetings but I notice I don't do that any more. Anyone experienced that?