What describes an allergic reaction generated by repeated exposure to a chemical or substance?

The term that best describes an allergic reaction generated by repeated exposure to a chemical or substance is sensitization. This process involves the immune system becoming increasingly sensitive to a particular substance after initial exposures. Once sensitization occurs, subsequent contacts with that substance can trigger an allergic response, leading to symptoms such as redness, itching, and inflammation.

This concept is essential in the field of cosmetology, as many products contain chemicals that could lead to such allergic reactions upon repeated use. Understanding sensitization helps cosmetologists to take necessary precautions when using various products on clients, thereby ensuring their safety and comfort.

While other options, like irritation and allergic dermatitis, may relate to skin reactions, they do not specifically address the mechanism of the immune system's heightened response that occurs after repeated exposure. Hypersensitivity is a broader term encompassing various excessive immune responses, but sensitization specifically refers to the process leading to that heightened reaction.