Vitamin B12 and methylcobalamin are not recommended to be taken together, because methylcobalamin belongs to the endogenous vitamin B12, and taking them together belongs to the duplication of medication. 1. Vitamin B12: after entering the body can not directly participate in the body metabolism, need to be absorbed after combining with the internal factors, after entering the blood need to be transformed to be active, its main function is to promote protein biosynthesis, promote the development and maturation of red blood cells, increase the utilization rate of folic acid, and prevention of cardiovascular system diseases. 2. Methylcobalamin: It is an endogenous vitamin B12, a kind of vitamin B12. Compared with vitamin B12, methylcobalamin is more favorable to be absorbed by human body. Its main function is that it can improve neuron conduction and nourish peripheral nerves, which is suitable for the treatment of peripheral neuropathy. Since vitamin B12 and methylcobalamin have similar effects, it is not recommended to take them at the same time. And should be under the guidance of the doctor to choose the medication, and strictly follow the doctor’s instructions to take.