Methylcobalamin is methylcobalamin tablets and b12 is vitamin B12 tablets. Both can usually be taken at the same time and there is no conflict. Vitamin B12 tablets should be avoided in combination with chloramphenicol and should not be taken at the same time as vitamin C. Also p-aminosalicylic acid, phenobarbital, and cholestyramine are not suitable for use with vitamin B12. Methylcobalamin tablets are not included here, and there are no drugs that cannot be used together with methylcobalamin tablets for the time being. Mecobalamin tablets are generally used to treat peripheral neuropathy. Common adverse reactions include nausea, vomiting, diarrhea, and occasionally skin rash. Occasionally, skin rashes are seen, which can be relieved after stopping the drug. Vitamin B12 tablets are suitable for megaloblastic anemia. It may show side effects such as low blood potassium and high uric acid. When side effects are obvious after taking both, immediate medical attention is required. Vitamin B12 tablets have no obvious contraindications, but it should be noted that people who are allergic to the two drugs are prohibited from taking them, and you need to consult with a physician before taking any medication and follow the doctor’s instructions.