When a correct substance is properly administered but has an adverse effect this is called?

When a correct substance is properly administered but produces an adverse effect, this is referred to as an "adverse drug reaction" (ADR). ADRs can occur due to individual variability in drug metabolism, interactions with other medications, or underlying health conditions. These reactions can range from mild side effects to severe and potentially life-threatening complications. Monitoring and reporting such reactions are essential for patient safety and improving therapeutic outcomes.