Ad fatigue, explained.

Ad fatigue is the decline in an ad's performance that sets in once its audience has seen it too many times. Frequency climbs, CTR falls, and CPA rises while the ad itself hasn't changed — people have learned to tune the message out.

Look for several signals drifting together over one to two weeks with nothing else changed: frequency climbing while results drop, CTR falling steadily, CPA grinding up (a rising CPM is supporting evidence at most), and hook rate sliding on video. One metric alone isn't proof; the joint trend is.

There's no magic number, and Meta doesn't give one. Meta's Reach & Frequency glossary suggests frequency may average 1 to 2 per ad set or be much higher depending on budget, audience size and schedule, and its frequency help page says that if performance drops as frequency rises, your audience may be experiencing ad fatigue. Some practitioners start watching around 3–4 on cold prospecting, but that's a rule of thumb, not a Meta threshold; retargeting tolerates higher because repetition is the point. Judge frequency together with the CTR trend rather than on its own.

Make a materially different ad, not a new thumbnail or a recut. Meta's own guidance for creative fatigue is a new ad with an image or video that is "materially different from the original creative"; swapping thumbnails or colours rarely helps because the audience is bored of the ad, not the pixels. If the selling point still works (competitors are still running it), iterate: keep the reason to buy and change the execution — new hook, opening and format. If the selling point is spent, make a new concept: find an angle currently winning in your niche that your audience hasn't heard from you and rebuild the ad around it — new hook first.

It depends on audience size, budget, and how distinctive the creative is — but operators report cycles have shortened in the Advantage+ era, where, with broad targeting, the creative is the main lever you control: a winner burns through the people it resonates with faster, so "worked for months" has quietly become "worked for weeks" for many accounts.

Watch cost per result first. Meta says people may be less likely to engage with a fatigued ad, which can lead to a higher cost per result, and it shows a "Creative fatigue" status when an ad's cost per result is at least twice that of ads you've run in the past. That status only appears for ad sets with one creative, so you won't see it on dynamic creative or Advantage+ catalog ads. Meta also notes that if your ad set is optimised for conversions, CPM may not be a good indicator of performance. So a rising CPM on an old creative is supporting evidence at most, not the diagnosis.

Ask whether the ad ever worked. Converted for weeks and then faded → fatigue; keep the appetite and make a materially different ad (a new execution while the selling point still works, a new concept once it's spent). Never converted at all → the creative hypothesis was wrong from day one; it needs a new hypothesis, not a refresh.