delayed toxic response

A delayed toxic response is a reaction to a substance that takes more than a few days to develop after exposure. This contrasts with immediate toxic responses, which occur within a few days. The timing of a toxic response depends on factors like how quickly the substance is absorbed, transformed, distributed, and excreted, as well as how fast it acts at its target site.1

Delayed hypersensitivity, also known as Type IV hypersensitivity, is a cell-mediated immune reaction primarily involving T cells rather than antibodies. This type of reaction is characterized by its delayed onset, typically appearing 18 to 24 hours after exposure to an antigen, and can persist for some time. A common example is contact hypersensitivity, such as that caused by poison ivy, where a chemical interacts with skin proteins, leading to inflammation and dermatitis.2