Are B12 Shots Safe? Royal Palm Beach Medical Group Can Allergy Shots Give You a Headache? Sahara West Signs You May Have a B12 Deficiency Vitamin B12 deficiency can cause symptoms like headaches, fatigue, depressive mood, gastrointestinal issues, and more. While vegetarians are at a higher risk of vitamin B12 deficiency, it can affect non vegetarians too. Check B12 Injections for Energy: Benefits and How It Works AZ IV Medics