Patient's question:
It's time for the child to get the hepatitis B vaccine. We went there on time. When we came home that evening and prepared to apply a warm compress, we noticed redness and swelling on her arm. There was some mild swelling, and the child also mentioned that it was a bit itchy and red. What could be the reason for redness and swelling on the arm after the child receives the hepatitis B vaccine?Doctor's answer:
Children may experience low fever, redness, swelling, and hard lumps at the injection site after vaccination, which is normal and typically occurs within 24 hours of vaccination. Severe reactions at the injection site can cause nearby lymph nodes and lymphatic vessels to become inflamed. The size of the swollen lump at the injection site is classified as mild, moderate, or severe. Mild lumps are less than 2.5 cm in diameter, moderate lumps are between 2.5 and 5 cm, and those larger than 5 cm are considered severe reactions, which can last for several hours or days.If the local redness and swelling are severe, warm compresses can be applied (heat should not be applied after BCG vaccination). Apply warm compresses once in the morning and once in the evening, each lasting about 5 minutes. It is also important to change underwear frequently to avoid infection if the area breaks open. If local infection occurs, gentian violet ointment can be applied. These symptoms usually disappear within a day with warm compresses or on their own.
For example, with the measles vaccine, most recipients will not have any special reactions. Some may experience localized swelling and pain for 1-2 days. Approximately 5% of children may develop a rash 1-2 weeks after vaccination, and 5-10% may develop a fever 4-10 days after vaccination, ranging from mild (37-37.5°C) to moderate (37.6-38.5°C). A fever above 39°C is considered severe. Additionally, some children may experience symptoms such as headache, dizziness, weakness, chills, nausea, vomiting, abdominal pain, or diarrhea. These reactions usually subside within 24 hours and rarely last more than 3 days.
If the fever is severe, fever-reducing medication can be taken. Once the temperature returns to normal, other symptoms should also resolve on their own. However, if the high fever persists or other abnormal symptoms occur, seek medical attention promptly.