Hepatitis B immunoglobulin is still useful if you didn’t get it within 12 hours. The effective time of immunoglobulin vaccination for hepatitis B patients is as follows: 1. After accidental exposure, vaccination within 12 to 24 hours can generally avoid hepatitis B virus infection. 2. After accidental exposure, vaccination within 48 hours can still effectively reduce the chance of hepatitis B virus infection. 3. If vaccination is not given within 72 hours of exposure, vaccination can be given 3 days or 1 week after exposure to reduce the chance of hepatitis B virus infection. Hepatitis B immunoglobulin is used to prevent hepatitis B. The more common adverse reactions are transient headache, panic and nausea, etc. Hepatitis B immunoglobulin is contraindicated in people who are allergic to it, and should not be used if precipitates are found. In addition, the application of hepatitis B immunoglobulin has certain risks, patients need to get the guidance of specialists, not unauthorized application.