It's a common and confusing situation: an ad campaign that had been performing well for weeks suddenly starts generating fewer clicks and fewer sales, with nothing having been changed. Almost always, the cause is ad fatigue.
What ad fatigue is
It happens when the same audience sees the same ad too many times in a short period. At first it grabs attention; past a certain point, it starts generating indifference or outright rejection, and the campaign's performance drops even though targeting and budget remain the same.
How to spot it
The frequency metric (how many times, on average, each person has seen the ad) is the most direct indicator. When cost per result starts rising while frequency keeps climbing, and nothing else has changed in the campaign, ad fatigue is the most likely explanation.
Why it happens faster than it seems
With small or heavily targeted audiences, the same reduced group of people receives the ad over and over within a few days, speeding up fatigue. The more specific and small the target audience, the sooner this problem shows up, even with moderate budgets.
How to fix it
Refreshing the creative (new images, videos or copy) is usually the fastest fix, since it resets the sense of "novelty" for the same audience. Broadening the target audience, or rotating between several different audiences, also helps spread out exposure and slow down the wear.
Frequently asked questions
How often should ads be refreshed to avoid fatigue?
It depends on audience size and budget invested, but as a general guideline, reviewing frequency every one or two weeks and refreshing the creative once it starts climbing noticeably is usually enough.
Does ad fatigue affect all platforms equally?
The principle is the same everywhere, but it shows up sooner on platforms with smaller or more expensive audiences, where the same group of people receives repeated impressions more often.
Does increasing the budget help mitigate ad fatigue?
Not directly; if the problem is an exhausted audience, more budget usually translates into more frequency on the same people, making the problem worse instead of solving it. What helps is broadening or rotating the audience, not simply spending more.