Experiencing itchy, red welts after your peptide injections? You're not alone, and the peptide itself usually isn't the problem. The real culprits? Histamine release, mast cell activation, gut imbalances, hormonal shifts, or Vitamin B12 Allergies Are Rare But Real. Here's Why. And the Food Babe Weighs In. American Council on Science and Health Common & Rare Side Effects of Vitamin B12 Injections HELP! I think I developed fungal acne from B12 injections : r Fungalacne