what happens after taking b12 injection Vitamin Vitamin B12 Injections in Oakland,

Symptoms may include: Shortness of breath Red, flushed skin Headaches Rapid weight gain, polycythemia (increased red cell mass), hypokalemia, CHF, pulmonary edema, and vascular thrombosis are mostly observed in therapeutic contexts where vitamin B12 is administered aggressively or over extended periods

I have had about 3 ECGs in my life because of this, all okay but sometimes I wonder if I have had a heart attack and just survived it

Yes, split dosing is a valid approach, particularly for doses at the higher end of the range (450-500mcg daily)

You might also feel numbness or tingling in the hands and feet , have trouble walking, or notice changes in thinking