According to Dr Aravinda, high doses of vitamin B12 used to treat deficiency can cause: Headache Nausea and vomiting Diarrhoea Fatigue or weakness Tingling sensation in hands and feet Dr Aravinda further commented that possible interactions with other drugs include Aminosalicylic acid
But itll take longer for you to feel the effects, even if the B12 shots are already working
Clinical Knowledge Summary
And since having too much B12 isnt harmful (the body simply excretes the excess), its easier and cheaper to just get a shot (B12 injectables cost $14 apiece if bought online or $20 to $70 at a spa or doctors office)
Researchers who dont verify sourcing risk introducing batch-to-batch inconsistency into their work, which can undermine reproducibility a foundational requirement in scientific research
Many people report feeling more energised and focused within a few days, although results can vary depending on individual needs