Most medical documents indicate you might experience any of these: Mild diarrhea and/or upset stomach Difficulty breathing or swallowing Weight loss or weight gain Nervousness or restlessness Nausea or vomiting Headaches or migraines Paresthesias (tingling sensations) Rhinitis (chronic sneezing or a congested, drippy nose) Skin reactions, such as rash, itching, swelling, blisters, or pain at the site of injection Light joint pain Lightheadedness or dizziness Chest pain or discomfort Low blood potassium levels Irregular heartbeat Chills, night sweats, fever, or hot flushes General feeling of sickness However, people often fail to recognize that many side effects of vitamin B12 injections are consistent with B12 deficiency itself

The authors reported that intra-articular AOD-9604 injection in the rabbit osteoarthritis model produced macroscopic, histologic, and biomechanical evidence of cartilage preservation relative to untreated controls, with the combination of AOD-9604 plus hyaluronic acid yielding the most consistent chondroprotective effect [4]
Conditions affecting any stage of this absorption pathwayincluding pernicious anaemia (an autoimmune condition destroying intrinsic factor-producing cells), Crohn's disease, coeliac disease, or surgical removal of stomach or ileal tissuecan significantly impair B12 absorption despite its water-soluble properties
A deficiency in Vitamin B12 can lead to fatigue, weakness, and even neurological complications