It is not necessary to use vitamin B12 again when taking methylcobalamin for herpetic neuralgia as both medications have the same composition. Methylcobalamin tablets are endogenous vitamin B12, methylcobalamin and vitamin B12 compared to the neuron conduction has a good improvement effect, can be used for the treatment of vitamin B12 deficiency caused by megaloblastic anemia, can also be used for the treatment of peripheral neuropathy. Therefore, when taking methylcobalamin tablets, do not need to take vitamin B12, these two drugs at the same time belong to the duplication of drugs, resulting in overdose, leading to adverse drug reactions, and is not conducive to the recovery of the disease. Methylcobalamin tablets occasional adverse reactions are rash, headache, feverish feeling, etc.; allergic to the ingredients of the drug is prohibited, pregnant and lactating women should be cautious. If there is a need for medication, it is recommended to use the drug under the guidance of a doctor, do not abuse the drug on your own, so as not to cause adverse reactions.