Rare side effects of B12 shots (require medical attention) Serious reactions to B-12 shots are uncommon, but its important to be aware of them: Allergic reaction, including rash, hives, dizziness, or trouble breathing Significant swelling, pain, or warmth that worsens at the injection site Palpitations or chest discomfort Signs of drug interactions, especially if you take multiple prescription medications If you experience symptoms that feel intense, progressive, or unusual, you should contact your provider right away
[18] Lactation studies demonstrate that maternal injections modestly elevate breast-milk B12 concentrations without adverse infant outcomes, supporting compatibility with breastfeeding while underscoring the need for maternal repletion to prevent neonatal deficiency
doi: 10.1126/science.1123965
Some might need injections every two weeks, while others might do fine with less frequent ones
Modification of cellular autophagy protein LC3 by poliovirus