Headache After B12 Shot: 3 Effective Strategies to Feel Better Nutritional Supplements for Your Headache Relief: Beverly Hills Migraine and Pain Management Institute: Chronic Pain Physician Headache Specialists Common & Rare Side Effects of Vitamin B12 Injections Fun Fact Friday! Ever wondered Why is my B12 injection red? All B12s are cobalamins they have a cobalt atom at the center of a special ring shaped molecule called Signs You May Have a B12 Deficiency