Over time, you may not experience any side effects at all with the shots.
Every component ships with its lot-matched COA
doi: 10.1172/JCI118990 512 Cabral-MarquesOMarquesAGiilLMDe VitoRRademacherJGntherJet al
See what a recent study showed in our updated answer to the question: Which supplements help to improve energy and decrease fatigue
(There are several studies involving animals, but not human subjects.) What research does show is that people who are overweight tend to be low in vitamin B12
Observed effects in human trials Reported adverse events across the IV and oral trials included headache, fatigue, dizziness, nasopharyngitis, diarrhea, flatulence, increased appetite, nausea, and back pain