Hi, I am a new member and was just checking the site when I came across your situation. I had low levels of B-12 several years ago. It takes 5 years for you to deplete your B-12 storage levels, so it will probably take you a while to get them back up. I took 1000 mcg daily disolved under my tongue. At the same time I went to chiro and had accupunture. I would say it took me about 5 months to start feeling like myself again. My husband said he noticed an immediate change when I started taking the B-12. I hope this helps.