The following pharmacological definition has been taken from the Pharmacology and Experimental Therapeutics Department Glossary at Boston University School of Medicine.

Cross-Tolerance:

Tolerance to a drug that generalizes to drugs that are chemically related of that produce similar affects. For example, a patient who is tolerant to heroin will also exhibit cross-tolerance to morphine.

The copyright of the text is hold by Trustees of Boston University. Permission has been granted for its use in this blog.