What is the effect called when two drugs enhance each other's impairing effects?

The correct term for the effect when two drugs enhance each other's impairing effects is "synergistic." This occurs when the combined effect of two substances is greater than the sum of their individual effects. In pharmacology, a synergistic effect can result in more significant impairment or enhanced effects than what would be experienced if either drug was taken alone.

For example, if two depressants are taken together, their combined effects might lead to heightened sedation or impairment that exceeds what each drug would produce on its own. Understanding this concept is crucial for law enforcement, especially when assessing situations related to drug use and impairment.

The other terms are either less appropriate or used in different contexts. "Overlapping" typically refers to the simultaneous presence of effects rather than their enhancement. "Additive" refers to a scenario where the effects of two drugs sum together but do not exceed their individual impacts. "Composite" generally refers to a combination of elements, but it is not a standard term used to describe the interaction of drugs in this specific context.