It is possible to experience flushing when taking methylcobalamin, possibly due to a drug allergy. Methylcobalamin is a derivative of vitamin B12, which belongs to coenzyme B12, and it is easier to enter the nerves, and it has a good transmissibility to the nerve tissues, and it can play a good role in nourishing the nerves. Methylcobalamin usually does not cause flushing, but some patients are prone to allergic reactions after taking it, which can cause skin rashes, redness and swelling of the face, and may show facial flushing. Mecobalamin itself contains the metal element cobalt, and long-term use can lead to side effects such as decreased appetite, nausea, vomiting, acid reflux, bloating, abdominal pain, diarrhea, and heartburn. These side effects need to be stopped in time to avoid harm to the body. The use of methylcobalamin must be under the guidance of a professional doctor, do not blindly use or increase or decrease the dosage by yourself. At the same time, any discomfort after taking methylcobalamin, you need to go to the hospital for examination in a timely manner, listen to professional doctor’s advice to deal with.