The most common side effects are mild and include injection site reactions (redness, slight swelling, or tenderness), mild headaches during the initial days of use, and occasional dizziness or lightheadedness
this compound remains investigational
For individuals with a B12 deficiency, injections may help restore energy levels and improve overall well-being, which could indirectly support more active behavior and possibly weight management
The lower end showed measurable effects on fat metabolism but slower results
Vitamin B12 shots may not be suitable for people with a history of: sensitivity to vitamin B12 Lebers disease, which affects the optic nerve kidney problems hypokalemia (low potassium levels) deficiencies in other nutrients, particularly folic acid and iron Vitamin B12 injections typically begin to work straight away
Theoretical and route-specific risks FDA's 2024 review specifically flagged that no published human exposure data exists for the subcutaneous, transdermal, or intranasal routes that compounding pharmacies have offered
