Generally, vitamin B12 is considered safe, even at high doses, because it is a water-soluble vitamin and excess amounts are usually excreted in the urine. There is no established upper intake level for B12 due to its low potential for toxicity. However, in rare cases, some individuals may experience mild side effects such as skin rashes, diarrhea, or headaches. It is important to consult with a healthcare provider before starting any supplementation, especially if there are underlying health conditions.
