Vitamin B12 has a low potential for toxicity. The body excretes excess amounts in the urine, making it relatively safe even at high intakes. Unlike fat-soluble vitamins, water-soluble vitamins like B12 do not accumulate to toxic levels under normal circumstances. There is no established tolerable upper intake level for B12 due to its low toxicity. However, some reports suggest that extremely high doses might lead to minor side effects such as acne or rosacea, though these are rare.
