Currently, the hepatitis B vaccine is relatively safe and effective, and allergic reactions are less likely to occur. Allergic reactions caused by hepatitis B vaccination are generally manifested as rash, itchy skin, local redness, swelling and pain, fever, etc. More serious cases may result in anaphylaxis. Local reaction 1. redness, swelling and pain: mild redness, swelling and pain at the injection site, which can generally dissipate on its own after 2-3 days; 2. hard nodes: hard nodes can generally be absorbed on their own after 1-2 months; 3. local sterile suppuration: pus is usually extracted repeatedly with a syringe, and in serious cases, the wound is widened and cleared, and the patient can go to surgery for help. Systemic reactions: 1. papules: red papules appear on the body after vaccination, which usually dissipate gradually; 2. fever: transient febrile reactions may occur within 72 hours after vaccination, which generally last 1-3 days and can be relieved by themselves; 3. discomfort: weakness, dizziness, nausea, vomiting, etc., which are generally not particularly serious and usually do not require special treatment and can gradually return to normal; 4. anaphylaxis 4) Anaphylactic shock: Serious cases may occur within 1 hour after vaccination and should be sent to the emergency room quickly. In addition, it is generally recommended to stay for at least 30 minutes after vaccination and leave only after determining that there are no obvious abnormalities. There is no need to worry about the above-mentioned symptoms, as they can be treated properly and promptly.