Negative Keywords on Amazon: The Fastest Way to Cut Wasted Ad Spend

Last month we took over a supplement brand's PPC account that was spending $85K/month with a 42% ACoS. Within three weeks, we dropped ACoS to 29% without cutting a dollar of budget. The single biggest lever? Amazon negative keywords. They had almost none.

If you're running Sponsored Products or Sponsored Brands on Amazon and you're not adding negative keywords weekly, you're burning money. Full stop.

What Amazon Negative Keywords Actually Do

Negative keywords prevent your ads from showing on specific search terms. When you add "cheap" as a negative keyword, Amazon won't serve your ad to anyone who includes "cheap" in their search. You stop paying for clicks from shoppers who were never going to buy your product.

Two match types are available for negatives:

• Negative Phrase: Blocks your ad whenever the search term contains that phrase in order. "Dog food" blocks "organic dog food" and "dog food grain free" but not "food for dogs."
• Negative Exact: Blocks only the exact search term. "Dog food" blocks "dog food" and nothing else.

Use negative exact when you want surgical precision. Use negative phrase when you want to eliminate an entire category of irrelevant searches.

The 3 Sources of Negative Keyword Ideas

Source 1: Search Term Reports

This is where 80% of your negatives come from. Pull your Search Term Report from the Advertising console (or the API if you're running at scale). Sort by spend descending. Every search term that spent more than $20 with zero sales is a negative keyword candidate.

But don't stop there. Also flag search terms with a high click count and zero conversions. A term with 50 clicks and no sales has a 0% conversion rate — it's costing you $30-75 depending on your CPC, and it's probably irrelevant.

Source 2: Common Sense Pre-Launch Negatives

Before you even launch a campaign, add negatives for obvious mismatches:

• Competitor brand names (unless you're intentionally targeting them)
• Irrelevant product types that share keywords with yours
• Words like "free," "cheap," "used," "refurbished" if you sell premium products
• Size, color, or material variations you don't offer

A pet brand selling premium dog treats should negative out "cat treats," "dog food," "puppy chow," and "cheap dog treats" on day one. Don't wait for the search term report to tell you what you already know.

Source 3: Auto Campaign Mining

If you run auto campaigns (and you should for keyword discovery), they're a goldmine of negative keyword data. Auto campaigns cast a wide net. Review their search terms weekly and do two things simultaneously: promote converting terms into manual campaigns, and negative out non-converting terms from the auto campaign.

This creates a feedback loop. Your auto campaign gets more efficient over time because you're continuously pruning the dead weight.

How Often Should You Add Negatives?

Weekly. No exceptions. We run negative keyword audits every Monday for every brand we manage. The cadence matters because Amazon's search behavior shifts constantly — new products launch, seasonal terms emerge, and shoppers change how they search.

For accounts spending over $30K/month, we review search terms twice a week. The waste compounds fast at higher spend levels.

Campaign-Level vs. Ad Group-Level Negatives

This distinction trips up a lot of sellers. Campaign-level negatives apply to every ad group in that campaign. Ad group-level negatives only apply to that specific ad group.

Use campaign-level negatives for universally irrelevant terms. Use ad group-level negatives for traffic sculpting — directing specific search terms to the ad group with the most relevant product or the best-performing creative.

The Negative Keyword Audit Checklist

• Pull search term report for the last 14 days
• Filter for terms with spend > $15 and zero orders
• Filter for terms with 30+ clicks and sub-3% conversion rate
• Check for brand name misspellings driving irrelevant traffic
• Review auto campaign search terms for category mismatches
• Add negatives at the appropriate level (campaign vs. ad group)
• Document every negative added and the reason why

Amazon negative keywords are the fastest path to better ACoS in most accounts. If your PPC feels inefficient but you can't pinpoint why, start here. And if you want a team handling this weekly, our Amazon PPC management includes systematic negative keyword optimization as a core part of the service.