counteragent
/kaʊntərˈædʒənt/Definitions
1. noun
A person or thing that counteracts or opposes the effect of something else
“The company’s new marketing strategy was a counteragent to the negative publicity surrounding the product recall.”
2. noun
A substance used to neutralize or counteract the effects of another substance
“The antidote was a counteragent to the poison, and it saved the patient’s life.”