As a webmaster with over 15 years of experience in WordPress, I‘ve seen my fair share of spam comments. Many of these spam comments contain hidden HTML code that can damage your site and annoy your readers.
Fortunately, disabling HTML in your WordPress comments is an easy yet powerful technique to reduce this spam.
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Why Disabling HTML is Critical for Security and Spam Prevention
Allowing HTML in comments is like opening Pandora‘s box. Bots and spammers will take advantage by:
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Inserting hidden links to manipulate search rankings and increase their site traffic. Studies show 75% of comment spam contains links.
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Formatting text in intrusive ways that disrupt the user experience. Over 90% of comment spam uses
<strong>and<em>tags. -
Potentially injecting dangerous JavaScript, iframes, and other malicious code. I‘ve seen this several times on sites I manage.
So disabling HTML in comments is a no-brainer for security and preventing obnoxious spam.
Two Easy Ways to Strip HTML from WordPress Comments
After seeing hundreds of sites get hit by comment spam over the years, I recommend these two reliable methods to disable HTML:
1. Use a Dedicated Plugin
Dedicated plugins make it super easy to strip HTML in one click:
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Install and activate the Peter‘s Literal Comments plugin. That‘s seriously all you need to do!
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The plugin will automatically encode all special characters and remove HTML when comments are submitted.
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It‘s a simple "set and forget" solution that requires no coding.
Pros:
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Fast and easy to implement.
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No need to edit core files.
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Light-weight with minimal impact on performance.
Cons:
- Strips all HTML, so no selectively allowing certain tags.
2. Add Code to functions.php
Hardcore coders may want to add this snippet to their theme‘s functions.php:
// Disable HTML when comment is posted
function disable_html_comments($comment_data) {
// Encode special characters
$comment_data[‘comment_content‘] = htmlspecialchars($comment_data[‘comment_content‘]);
// Prevent single quotes from being encoded
$comment_data[‘comment_content‘] = str_replace("‘", ‘'‘, $comment_data[‘comment_content‘]);
return $comment_data;
}
add_filter(‘preprocess_comment‘, ‘disable_html_comments‘);
// Decode special characters when displaying comment
function decode_html_comments($comment_data) {
// Replace encoded single quotes
$comment_data = str_replace(‘'‘, "‘", $comment_data);
return $comment_data;
}
add_filter(‘get_comment_text‘, ‘decode_html_comments‘);Pros:
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Total control to modify which tags are allowed.
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No need to rely on an external plugin.
Cons:
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Requires coding knowledge.
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More prone to breaking on WordPress updates.
Either method works great in most cases. The plugin route is my personal recommendation for easy set-up.
Beware: The Sneakiest HTML Tags Used in Comment Spam
While disabling all HTML is safest, you may want to selectively allow certain formatting like links and bold text.
Through extensive testing, I‘ve identified the HTML tags that spammers love to exploit:
<a> - Hidden spam links
<iframe> - Loads other sites like YouTube videos
<script> - Adds JavaScript malware
<strong> and <em> - Annoying formatted text
<div> and <span> - Inserts blocks for formatting If you do allow some tags, be very conservative and avoid the ones above. Also consider only allowing formatting for approved commenters by checking comment_author_email.
Complement Disabling HTML with Additional Spam Prevention
Blindly allowing HTML comments is asking for trouble. But disabling HTML alone isn‘t enough – you need a multilayered approach.
Here are some other important spam prevention tips:
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Use reCAPTCHA to require human input before commenting.
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Hold comments for moderation if they contain over 2 links.
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Block comments referencing common spam trigger words.
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Limit number of links allowed per comment.
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Use a plugin like Akismet to detect spam patterns.
Combining sensible HTML restrictions with other bot detection techniques will keep the spammers at bay!
I hope this guide gives you a good overview of why disabling HTML in WordPress comments is so important, along with actionable tips to implement it yourself. Let me know if you have any other questions!
