Is there a 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.

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

• The campaign to reduce smoking backfired.

Counter-productive seems to fit your request pretty closely. The OED defines it as:

Having the opposite of the desired effect, tending to act against the attainment of an objective.

It’s a comparative neologism (apparently originally from US bureaucrat-speak in the 60’s), but is now well-established on both sides of the Atlantic in both formal and informal use:

The drug laws are counter-productive, and David Cameron knows it.
                — Tom Chivers, in the Daily Telegraph

But you’re right, they wouldn’t sue him (even if they had a case) because it’d just be counter-productive.
                — lightlee.tumblr.com [random Google result looking for casual use]