Live attenuated encephalitis B vaccine can be abbreviated as encephalitis B. Live attenuated encephalitis B vaccine stimulates the body’s immune system to produce antibodies against the encephalitis B virus, thus effectively preventing epidemic encephalitis B. Usually, people with normal immune systems are less likely to have adverse reactions to live attenuated encephalitis B vaccine. Common adverse reactions include fever, local symptoms, allergic reactions, neurological symptoms, digestive symptoms, etc. 1. Fever: It usually occurs a few hours to 24 hours after vaccination and is usually low fever, which can subside on its own without special treatment. If the symptoms persist or worsen, other diseases may occur and prompt medical attention is needed. 2. Local symptoms: There may be slight local redness, swelling, hard nodules, itching or pain at the injection site. Generally keep the area clean and dry, avoid scratching, it can subside on its own. If the symptoms are not relieved, or are accompanied by swollen lymph nodes in the vicinity, it is necessary to go to the hospital and be treated with topical or oral medication under the guidance of a doctor; 3. Allergic reaction: a local or generalized rash may appear in multiple parts of the body, manifesting as allergic urticaria or red papules with itching. Generally, it is necessary to visit a hospital and apply anti-allergic drugs under the guidance of a doctor; 4. Neurological symptoms: such as dizziness, weakness, headache, chills, etc.; 5. Digestive system symptoms: such as nausea, diarrhea, abdominal pain, indigestion, vomiting, etc. If the above-mentioned adverse reactions occur after vaccination, the symptoms are mild and mostly resolve on their own without special treatment. Those with serious symptoms should go to the hospital for treatment in time.