You should not take cyanocobalamin-based products if you: Have a known cobalt allergy Have Lebers hereditary optic neuropathy , as B12 can worsen vision in this condition Discuss nasal B12 with your clinician first if you have: Severe megaloblastic anemia Polycythemia vera or other bone marrow disorders Low iron or folate Kidney disease Are undergoing chemotherapy or using bone marrowsuppressing drugs Are pregnant or breastfeeding Possible Side Effects Most side effects reported with B12 nasal products are mild and temporary: Slight nasal irritation, burning, or dryness Runny or stuffy nose, sneezing, or sore throat Mild headache Nausea or a brief metallic taste Tingling or pins and needles sensations, especially early on as nerves recover Serious reactions are rare but require immediate medical care: Rash, hives, or intense itching Swelling of the face, lips, tongue, or throat Trouble breathing or swallowing Fever, chills, or signs of infection that dont match a simple cold If anything feels out of proportion or youre unsure, stop the product and speak with your healthcare provider or seek urgent care

Some people feel the effects within 2472 hours, while others may see benefits over time
1 StatPearls
Youll need the treatment regularly to maintain the results and the results might not be as significant as you're expecting
Tracking progress helps maintain motivation and identifies problems early
Clinics like Balanced Aesthetics + Wellness use Methyl B12 injections as part of their holistic anti-aging and wellness programs