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Injection Site Reactions

Meaning

Injection Site Reactions are localized adverse physiological responses that manifest at the precise anatomical location where a therapeutic agent, such as a peptide, hormone, or vaccine, has been administered via subcutaneous or intramuscular injection. These reactions are a common clinical observation and are typically characterized by transient, non-severe symptoms including localized erythema, swelling, mild pain, pruritus, or palpable induration. They primarily represent the body’s local inflammatory or mild immunological response to the mechanical trauma of the needle or the chemical presence of the injected substance.