Vomiting after vaccination is a normal post-vaccination reaction. For many vaccines such as New Crown vaccine, flu vaccine, rabies vaccine, etc., the discomfort of vomiting may occur after vaccination, which usually does not require special treatment and can be recovered after a few days of rest. The cause of vomiting after vaccination is speculated to be nausea and vomiting due to excessive fear and nervousness about vaccination, which usually belongs to the category of dizziness and can be relieved by psychological counseling and other aids. It may also be caused by indigestion due to eating poorly digested food, resulting in vomiting, which happens to be after the vaccination, causing a false association between vaccination and vomiting. If there is a lack of rest after the vaccination, it is possible that the weakness and overexertion may cause a reflexive urge to vomit. Of course, it can also be a side effect of the vaccine, but it is not common. Slight dry vomiting, redness, itching and pain at the vaccination site are minor adverse reactions to the vaccine, which usually do not require treatment and will disappear on their own after a few days. However, if symptoms such as high fever, diarrhea and general weakness occur, you need to go to the hospital for treatment, which may indicate a serious vaccine reaction or the presence of a vaccine allergy. In case of vomiting after vaccination, patients are advised to eat less and more often, eat a light diet, keep warm and avoid getting cold, and drink warm water to relieve the vomiting symptoms. At the same time, it is recommended to regulate emotions, relax and get enough rest, which will usually improve in a few days.