Semrush Shows Toxic Backlinks: Should You Disavow Them?

By Idea to Traffic Editorial Team · Published October 20, 2026 · Last updated October 20, 2026

You open a backlink audit in Semrush, Ahrefs or Moz and see a scary number: hundreds of "toxic" links, a pile of mirror pages, a few dozen spammy root domains you have never heard of. The tool suggests a disavow file. Before you build one, it helps to know that "toxic" is a label the tool invented, not a status Google assigns, and that for almost every small site the right move is to leave those links alone.

What "toxic" really means in an SEO tool

Backlink tools score each linking page against patterns they associate with spam: a low authority metric, a foreign language unrelated to your site, a domain on a known link list, hundreds of outbound links on one page, or a page that is a copy of another site. When enough of those patterns match, the link gets flagged. The score is a guess about how Google might see the link, built from the tool's own crawl, not from anything Google shares.

Google has said for years that its systems already ignore most low quality links on their own. John Mueller has repeatedly described random spammy links as something sites do not need to worry about, and has called "toxic links" a concept made up by tools. Ignored links pass nothing, good or bad. So a scraper that copied your post and kept your internal links does not hurt you; it simply does not count.

The audit in the Reddit thread that prompted this post is a good example: +827 mirror pages from +177 root domains. Mirror and scraper sites copy content automatically, and every copy carries your links with it. A growing site attracts more of them. That count is a side effect of being crawled and copied, not a sign that someone is attacking you.

When a disavow file is the right call

Google's own help page for the disavow tool says most sites do not need it. There are two situations where it makes sense:

• You have a manual action for unnatural links. Check Search Console > Security & Manual Actions > Manual actions. If it says "No issues detected", you do not have one. If it lists "Unnatural links to your site", you need to clean up and then disavow what you cannot remove.
• You or someone you hired built paid or manipulative links and you expect a manual action is likely. Typical cases: a link package bought from a marketplace, private blog network posts, or an old agency that did large scale guest post swaps. Here the links are not random spam; they look intentional, which is exactly what Google's link spam policy targets.

If neither applies, skip it. A disavow file built from a tool's toxic list can include perfectly fine links, such as a niche forum or a small foreign blog that mentioned you, and removing their value is a real cost with no matching benefit.

A ten minute check before you do anything

If your traffic dropped and you are wondering whether links are to blame, work through this in order:

1. Manual actions report. As above. No manual action means a link penalty, in the sense people usually mean, is not what you are looking at.
2. Dates of the drop versus known updates. In Search Console, open Performance > Search results, set the range to 3 months and compare the drop date with the Google Search Status Dashboard. A drop that lines up with a core or spam update is about content and site quality far more often than about links pointing at you.
3. Which pages lost clicks. Click the Pages tab and compare the two periods. If a whole section fell, look at that section first: thin pages, near duplicates, mass produced tool pages. If one page fell, look at what now outranks it.
4. Links you actually control. Did you buy links, join a link exchange, or pay for "guest posts" in the last two years? Those are the only links worth listing.
5. Your own technical basics. Accidental noindex, broken canonicals or a bad robots.txt rule cause far more sudden drops than spam links. Run your homepage and a dropped URL through the free site checker to rule those out in a few seconds.

In the same thread, another owner described growing to 3 million impressions and 12,000 clicks in three months and then falling sharply. Fast growth driven by large numbers of tool or programmatic pages, followed by a sudden drop, usually points at a quality reassessment of those pages. A disavow file will not change that.

How to build a disavow file correctly if you need one

If you do have a manual action or a set of bought links, keep the file small and precise. It is a plain text file, UTF-8 or 7-bit ASCII, one entry per line:

# Links bought from a guest post vendor, 2025
domain:cheap-guest-posts.example
domain:pbn-network-one.example
# Single page on an otherwise fine site
https://news-site.example/sponsored/best-tools-2025.html

Rules that trip people up:

• Use domain: for whole sites. Listing single URLs on a spam domain misses its other pages.
• Lines starting with # are comments and are ignored. Use them to note why each entry is there so you can review the file later.
• The file must stay under 2 MB and 100,000 lines. A file that size almost always means you pasted a tool export instead of choosing.
• The disavow tool works on URL prefix properties in Search Console. Upload at https://search.google.com/search-console/disavow-links, choose the property, and upload the file. Uploading a new file replaces the old one completely, so always edit the existing file rather than starting fresh.
• Expect weeks, not days. Google applies the file as it recrawls the listed pages.

For a manual action, removal comes first: email the site owners or the vendor and ask for links to be taken down, keep a simple spreadsheet of who you contacted and when, then disavow the rest and file a reconsideration request from the Manual actions report explaining what you did.

What to do with the toxic list instead

You do not have to ignore the audit completely. Use it for things that help:

• Spot scraped copies of your content that outrank you. That is rare for a site Google trusts, but if a mirror shows up above you for your own title, file a DMCA request through Google's legal removal form rather than a disavow.
• Find real mentions hidden in the noise. Sort the referring domains by traffic, not by toxicity, and look for actual sites that linked to you. Those are relationships worth building on.
• Turn off the noise. In Semrush's Backlink Audit you can move flagged domains to a whitelist so the score stops alarming you every week. In Ahrefs, filter by Domain Rating and dofollow to see the links that may carry value.

The short version: a toxic count is not a penalty, the Manual actions report tells you whether you have one, and the time you would spend building a disavow file is better spent on the pages that lost traffic.

Where this question came from

• r/SEO: Potential link network, Semrush showing toxic backlinks from mirror pages
• Google Search Console Help: Disavow links to your site
• Search Engine Roundtable: Google, more on when to ignore bad links

Questions about toxic backlinks and disavowing