Adverse reactions can be classified into different types based on their nature and onset. Immediate reactions occur within minutes to a few hours after administration and can include symptoms like anaphylaxis. Delayed reactions may take days or weeks to manifest and can include conditions such as serum sickness or certain types of autoimmune diseases. Adverse reactions can also be classified based on their severity: mild (nausea, headache), moderate (severe rash, high fever), and severe (organ failure, death).
