potentiation

https://doi.org/10.1351/goldbook.P04788
Dependent action in which a substance or physical agent at a concentration or dose that does not itself have an adverse effect enhances the harm done by another substance or physical agent.
See also: antagonism, synergism
Source:
PAC, 1993, 65, 2003. 'Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)' on page 2085 (https://doi.org/10.1351/pac199365092003)