Whether or not a daily vitamin B tablet is harmful to the body depends on whether or not the body is deficient in this micronutrient. If the body lacks vitamin B, there will be ulcers on the corners of the mouth and itchy skin, etc. Supplementation of vitamin B tablets under the guidance of a doctor will not cause harm to the body, but rather improve the physical discomfort caused by the lack of vitamins. But when the body lacks vitamins, if you take vitamin B tablets indiscriminately, it will lead to the accumulation of vitamin B in the body, affecting the normal metabolism of the body, which will lead to the crowd to diarrhea, nausea, vomiting, itchy skin and other symptoms. So when you want to supplement B vitamins or other vitamins, you need to go to the local hospital for a trace element examination to find out if you are deficient before supplementing.