TL;DR Summary

• Sites can use the HTML tag rel=”nofollow” to instruct search engines not to credit a link with any importance for the purposes of SEO
• These instructions don’t carry authority: they are merely suggestions
• Search engines, including Google, choose whether to listen to the nofollow suggestion or not
• They generally do not listen to the suggestion
• If you can generate contextually relevant backlinks from sites which use nofollow tags, go for it! You’ll likely get value from them regardless. Just don’t be spammy.

The History of HTML Link Relationship Tags

As the name implies, a link relationship tag provides context to search engines and other automated crawlers on the nature of the relationship between the source page and the destination page. Some very common ones which marketers may run into are rel=”sponsored”, which denotes links in sponsored content, rel=”ugc” which denotes links in user-generated content, and rel=”nofollow”, which is supposed to tell search engines to completely ignore a link. There are over 100 link relations recognized by the Internet Assigned Numbers Authority, however, most of which are somewhat arcane and not used by search engines in any way which would be meaningful to marketers.

Link relationship tags, AKA rel tags, came into being in 2005, largely in response to the need for a nofollow tag to combat the excessive blog, comment, and forum spam which was extremely prevalent through the 2000s. Nofollow was proposed by Google’s Matt Cutts and Blogger’s Jason Shellen. For a long time, because they didn’t have a better option, Google and other search engines treated nofollow tags as law. Not only would they give no SEO benefit to nofollow links, but for a long time Google wouldn’t even index them.

The Evolution of Nofollow

As blog and comment spam became less of an issue, and as search engines became much more powerful and able to understand context, nofollow and similar relationship tags became less important to the search engines. Google effectively said as much in an announcement on their Search Central Blog on September 10, 2019:

When nofollow was introduced, Google would not count any link marked this way as a signal to use within our search algorithms. This has now changed. All the link attributes—sponsored, ugc, and nofollow—are treated as hints about which links to consider or exclude within Search. We’ll use these hints—along with other signals—as a way to better understand how to appropriately analyze and use links within our systems.

Why not completely ignore such links, as had been the case with nofollow? Links contain valuable information that can help us improve search, such as how the words within links describe content they point at. Looking at all the links we encounter can also help us better understand unnatural linking patterns. By shifting to a hint model, we no longer lose this important information, while still allowing site owners to indicate that some links shouldn’t be given the weight of a first-party endorsement.

As stated in the post, as of March 1, 2020 Google changed the role of link relationship tags, making them suggestions (or, in Google’s words, “hints”) rather than rules.

Context Is Key

As search engines continue to become more intelligent and human-like in their understanding of context within content, life science SEO professionals need to pay greater attention to context. A nofollow backlink with just one or two sentences in a comment on a relevant Reddit post may be worth more than an entire guest post on a site with little other content relevant to your field. Focus on doing all the things which you should be doing anyway, regardless of whether the link is nofollow or not:

• Post links only in relevant places
• Contribute meaningfully to the conversation
• Don’t be spammy
• Keep your use of links to a minimum
• Write naturally and use links naturally. Don’t force it.

Case: Laboratory Supply Network

Laboratory Supply Network started a backlinking campaign with BioBM in August 2023 which relied almost entirely on backlinks in comments from highly reputable websites (including Reddit, ResearchGate, and Quora), all of which use nofollow tags on their links. At the start of the campaign, their key rank statistics were:

• Average rank: 26.08
• Median rank: 14
• % of terms in the top 10: 45.00% (63 out of 140)
• % of terms in the top 3: 21.43% (30 out of 140)

Less than 8 months later, in March 2024, we had improve their search rank statistics massively:

• Average rank: 17.54
• Median rank: 7
• % of terms in the top 10: 61.11% (88 out of 144)
• % of terms in the top 3: 39.58% (57 out of 144)

Backlinking was not the only thing that Laboratory Supply Network was doing to improve its SEO – it has a longstanding and relatively consistent content generation program, for instance – but the big difference before and after was the backlink campaign (which, again, relied almost entirely on nofollow backlinks!) In the previous year, LSN’s search statistics didn’t improve nearly as much.

Conclusions

Backlinking has long been a key component of a holistic SEO strategy, and it remains just as important as ever. Links are an important signal telling Google and other search engines what content is relevant and important with regards to any particular topic. While many highly reputable sites use rel=”nofollow” to try to discourage link spam, most link spam is more effectively dealt with in other ways, such as manual, automated, or community-driven moderation. Google knows these other moderation tools have become more effective, and therefore allows itself to treat the nofollow tag as more of a hint than a rule. If you are performing SEO for your life science company, don’t avoid sites just because they use nofollow. You can achieve good results in spite of it.