Cross-tolerance occurs when:

Cross-tolerance refers to the phenomenon where the development of tolerance to one substance leads to a similar tolerance to another substance that is chemically or pharmacologically related. This occurs because the body’s adaptive mechanisms that respond to the effects of the first drug also apply to the second drug, resulting in an increased resistance to both substances.

For instance, if someone has developed a tolerance to alcohol, they may also find that they require higher doses of benzodiazepines to achieve the same effect, given that both substances affect similar pathways in the brain. Understanding cross-tolerance is crucial in clinical settings, as it highlights the importance of assessing an individual's drug history when prescribing medications or planning treatment strategies for substance use disorders.

This concept underscores the interconnected nature of various substances within the realm of addiction and pharmacology and illustrates that tolerance is not always isolated to a single drug, but can span across related substances.