As a general rule, negative keywords in Google Ads Performance Max (PMax) campaigns should be used with caution. The core strength of PMax lies in Google’s cross-channel algorithm (spanning Search, YouTube, Display, Discover, Gmail, and Maps), which automatically combines assets and traffic to maximize conversions. Over-filtering with negative keywords can limit the system's ability to discover new opportunities and disrupt the algorithm during its crucial learning phase.

However, obvious budget-wasting traffic should still be blocked. For example, if you sell premium hiking boots but consistently receive clicks for "cheap canvas shoes," adding those irrelevant terms to a negative keyword list will block low-quality traffic and protect your ad spend.

What Happens When You Apply Negative Keywords to PMax?

  • It only affects Search placements: PMax allocates budget across multiple channels. Negative keywords will only block traffic on the Search Network; they do not affect placements on YouTube, Display, Discover, Gmail, or Maps.
  • A slight reduction in impressions and clicks: Once you exclude specific terms, your ads will stop showing for those queries. While you might see a short-term dip in overall traffic, your invalid clicks will decrease, which typically optimizes your overall Cost Per Acquisition (CPA).
  • Impact on the machine learning phase: Restricting too many keywords early on prevents the system from gathering valuable search signals. It is highly recommended to let the campaign run freely for the first two weeks before applying precise exclusions based on actual performance data.

How to Set Up Negative Keywords in PMax Campaigns

To apply negative keywords to your PMax campaigns, follow this step-by-step workflow:

  1. Create a Negative Keyword List in the Shared Library: Go to the left navigation panel in Google Ads, click on Tools and Settings (or the Shared Library icon), and select Negative Keyword Lists. Create a new list and add broad, irrelevant terms (e.g., "cheap," "free," "jobs," or categories completely unrelated to your product).
  2. Apply the List to Your PMax Campaign: Navigate to your PMax campaign settings. Click on Settings > More Settings > Negative Keyword Lists. Select the list you just created and save your changes.
  3. Implement "Closed-Loop" Management: Review your PMax search terms report weekly. Add genuinely irrelevant, budget-wasting terms to your negative list. Note: Avoid blocking every low-converting term; focus strictly on completely irrelevant, broad-match categories.

Bonus Tip: Use URL Exclusions

If you want to prevent PMax from driving traffic to non-commercial pages on your website—such as blog posts, career pages, or FAQs—you can add these paths under the Excluded URLs setting in your PMax campaign. This ensures your budget is focused entirely on high-intent landing pages and product URLs.