The most commonly reported side effects are mild and tend to resolve within the first week of use
Brasch, Andrew McCaddon, John H.H
In addition, poor mood and concentration, irritability, depressive symptoms, inability to sleep normally, nausea, vomiting, diarrhea, and even numbness and tingling in your hands and feet can be signs of a Vitamin B12 deficiency
B12[8] deficiency, profound and marginal, is more common than many understand and often poorly managed, and can exacerbate or contribute to increased intestinal permeability, which in turn can trigger or worsen autoimmune responses, creating a complex cycle of interaction between these elements[9]
PubMed laboratory research record [PMID: 6792265] PubMed record related to this compound for laboratory literature review