Vitamin B12 shot side effects Most people tolerate vitamin B12 injections well, but possible side effects include: Mild: soreness or redness at injection site, mild diarrhea, nausea, headache, itching Rare but serious: allergic reactions (rash, swelling, difficulty breathing), low potassium (hypokalemia), dizziness or heart rate changes Get emergency medical help if you have signs of an allergic reaction to Vitamin B12: hives
See the AAAaAI review, a related PubMed case series and an FDA pharmacovigilance memo for more detail
Many patients who receive Vitamin B12 + MIC injections report feeling more alert and motivated, often noticing a reduction in sluggishness or brain fog
According to the World Health Organization, 39% of adults worldwide are overweight, and the most effective approach combines multiple strategies