The following reasons are common for not being able to take the hepatitis B vaccine: 1.They are hepatitis B carriers or currently have hepatitis B activity, and cannot take the hepatitis B vaccine. 2.They are allergic to certain components of the hepatitis B vaccine, and may induce serious allergic reactions after injection, so they should not take the hepatitis B vaccine for the time being. 3.If they have recently had allergic reactions, such as skin lesions, itching, eczema, etc., the vaccine should be postponed. 4. If you have recently had a cold or fever, or if you have a gastrointestinal infection such as diarrhea, or if you have other inflammatory diseases such as pneumonia or urethritis, it is also recommended that you do not inject hepatitis B vaccine temporarily.