Injections are generally for people with systems and bodies that have problems absorbing vitamin B12 and those who have undergone gastric surgery
For instance, homocysteine is one of the secondary tests for vitamin B12 deficiency
Monitor levels
Likewise, injecting too early can increase the risk of side effects, like feeling or being sick, constipation or diarrhoea, which may cause you to question your treatment and increase the chances of you stopping
Sikiric P, Seiwerth S, Rucman R, Turkovic B, Rokotov DS, Brcic L, Sever M
occasional reports of mild headache, transient jitteriness, or injection-site reactions