Red rash after vaccination is an allergic reaction triggered by vaccine, which is mainly categorized into two major types: rapid-type and non-rapid-type, and can be treated with medication and observation.
Rapid-onset: IgE-mediated type I allergic reaction, the rash often appears within minutes to 24 hours after vaccination, if there are no other accompanying symptoms can be left untreated, and most of them can subside within a week. If accompanied by itching, oral antihistamines (e.g., loratadine) can be taken to relieve it. If symptoms such as dyspnea, angioedema and abdominal pain occur, go to the hospital immediately.
Non-rapid type: Including type II, III and IV allergic reactions, the rash usually appears a few hours to a few days after vaccination, and the rash can last for 2~3 weeks, which is usually self-limiting and does not require treatment, and does not affect future revaccination.
It is recommended to go to the hospital, if necessary, to complete the relevant examinations to detect the allergic components in order to avoid the risk of treatment, the above drugs need to be used in accordance with medical advice.