Vitamin B1 and methylcobalamin take the same generally does not exist drug conflict, but after taking the side effects, depending on the two drugs themselves, and at the same time with no great relationship. Vitamin B1 and methylcobalamin can be taken at the same time, there is no interaction between the two, and there will be no drug conflict, if there are side effects, generally have no relationship with the simultaneous taking, mainly depends on the two drugs themselves side effects. When taking vitamin B1, it is important to know that those who are allergic to the ingredients of the drug need to be prohibited, and pregnant and breastfeeding women need to use with caution. Prolonged use may cause unusual reactions, such as dizziness, headache, fatigue, etc., which will be relieved on their own after prompt cessation of use. When taking methylcobalamin, it is forbidden to use it if you are allergic to the components of the drug, and children should take it under supervision. The drug may cause loss of appetite, nausea, vomiting, etc. In mild cases, no special treatment is needed, while in severe cases, the drug should be discontinued promptly. If you need to take vitamin B1 and methylcobalamin together at the same time, you should be under the guidance of a medical professional, and should not mix and match the medication on your own.