Still feeling tired even after good sleep? It might be more than just stress it could be Vitamin B12 deficiency., In Part 2, Dr. Pydi Satish, Consultant General Physician, explains the signs, causes, B12 Injection When Is It Worth It and What Can You Feel After One Dose? LondonMassage4U Feeling worse after B12 Injection: Answering concerns. La Vie Med Spa B12 Lipotropic Injections for Weight Loss Burn Fat, Boost Energy, Lower Cholesterol, Doctor Supervised RWLC How Long Does It Take Vitamin B12 Injections to Work? Feeling exhausted no matter how much you sleep? Vitamin B12 deficiency is more common than people think affecting up to 15% of people. Treatment may include oral supplements or B12 injections. Save