The exact mechanisms leading to idiosyncratic reactions are not fully understood, but several theories exist. One common explanation is the role of genetic factors that affect drug metabolism. For instance, variations in cytochrome P450 enzymes can lead to abnormal accumulation or breakdown of drugs, resulting in unexpected toxicity. Another possibility is immune-mediated responses. Some individuals may have a predisposition to mount an immune response against drug-modified proteins, leading to conditions such as drug-induced hepatitis or skin reactions like Stevens-Johnson syndrome.
