No worries on overdosing B12. There is no upper level tolerable intake. At the moment I'm not sure if there's an uppter tolerable intake for other B vitamins since a lot of injectable vitamin b12 solutions contain other B vitamins such riboflavin, niacinmide, etc. If you want, I'll get back to you on that. Just be sure to drink plenty of water. Usually b12 is used for macrocytic anemia, which is treated with just a couple injects a month. Sometimes only once per month. That is why the box says 100mcg to 1000mcg once per month since b12 injections are used to treat macrocytic anemia.

The dosage and frequency of injections depends on what your trying to accomlish. If you're practicing injections for future AAS use, then ed injections are fine. I used to inject 1000mcg ed btw, but then again I was practicing injecting for AAS.

If you're just looking to increase your appetite and energy levels, I'd use it sparingly. Maybe up to a couple times a week. Since, for me anways, the appetite and energy effects dissipate pretty quickly, after a week or so. I'd use it Just when you're run down, or appetite is in the shitter.