Idiosyncratic reactions occur the ___________ time a drug is given to a patient.

Idiosyncratic reactions are unique and unexpected responses to a medication that can occur upon initial exposure to a drug. These reactions are not related to the drug's pharmacological properties and may arise from individual genetic factors, resulting in unpredictable effects that differ from typical side effects. Since idiosyncratic reactions can manifest upon the very first dose of a medication, recognizing the importance of observing patients closely during their initial exposure is crucial for healthcare professionals. This understanding helps in managing patient safety and the potential need for alternative therapies if an adverse reaction is identified early on.