Side Effects of Vitamin B12 Supplements
It is basically safe to take vitamin B12 supplements orally at recommended doses. Injectable forms can help treat significant deficiencies. However, there are some possible side effects, such as nausea, vomiting, dizziness, headache, skin rash, itching, mild diarrhea, swelling, vein thrombosis, or even polycythemia vera, slow and rare growth of blood cancer. In some cases, you would experience allergic reactions after taking B12 supplements. This leads to symptoms like difficulty breathing and swallowing, and swelling of the throat, tongue, and face. [6]
