Learn English – word for when an action has an effect opposite to the one intended


Is there a word or phrase to express the concept of an action having the opposite effect of the expected outcome?

For example, a drug taken to cure headaches that actually causes headaches, or an advertising campaign designed to deter smoking that leads to an increase in smoking.

Best Answer

A common idiom expressing this concept is "to backfire". For example:

  • The campaign to reduce smoking backfired.