How to Limit Seizure Triggers in Digital Content

Published January 31, 2023

When we think about ensuring digital accessibility, we tend to think about it from the standpoint of functionality and usability. For example, many rules and regulations regarding font size on web pages accommodate individuals with visual impairments and can also benefit all users.

But digital accessibility isn’t just about convenience. It also involves the safety of users: for example, the safety of people who have seizures. People with photosensitive epilepsy are at risk of suffering seizures in response to certain types of digital content.

Though photosensitivity isn’t that common of a seizure trigger, it can still cause harm. As such, it is critical for developers to learn how to reduce potential seizure triggers in their content. 

Understanding digital seizure triggers

Photosensitive epilepsy isn’t as common as other forms of epilepsy, but it can have harmful consequences. Photosensitive epileptic seizures are usually triggered by lights or images flashing at a rate between 3 and 55 hertz. Or, in other words, 3 to 55 flashes per second.

Lights aren’t the only thing that can trigger photosensitive seizures. Patterns can also be a trigger. Some people can be sensitive to geometric patterns with high-contrast colors. Common triggering shapes include stripes and bars. 

According to the Epilepsy Society, “Patterns are more likely to be a trigger if they are changing direction or flashing, rather than if they are still or moving slowly in one direction.”

Now that we have a better understanding of what triggers photosensitive epilepsy, let’s get into ways that developers can reduce seizure triggers on their content.

Adhere to WCAG

Flashing lights and images are the most consistent trigger for photosensitive epilepsy. Because of this, developers should abstain from using them in their content. 

The Web Content Accessibility Guidelines (WCAG) forbids the use of flashing lights or any seizure-triggering content. Section 2.3 states, “Do not design content in a way that is known to cause seizures or physical reactions.” 

Content must not flash between 3 and 55 Hz for longer than one second, and providing an on/off switch does not permit the inclusion of such content. Seizure onsets can happen too quickly to allow such a risk.

Provide trigger warnings

If developers are unsure whether content on a page will trigger a seizure, it’s better not to take any chances. Even one second of exposure could trigger a photosensitive epileptic seizure. 

To lessen the chance of harm, developers should provide trigger warnings for risky content. Trigger warnings can help at-risk users steer clear of potentially suffering a seizure. 

The use of trigger warnings has become quite common on various social media platforms. In 2020, TikTok announced that it would launch features to help reduce seizure triggers on its platform. 

One of these features is a skip option that reduces user exposure to potentially triggering videos. According to TikTok’s press release, “With this new feature, viewers who come across a photosensitive video will receive a notification inviting them to ‘Skip All’ future photosensitive videos.”

Limit access to questionable content

Another way to reduce the risk of seizures is to limit access to content that could cause them. Developers can do this by removing risky content from high-traffic areas of a website or platform. 

One way to do this is to move the content to a page that users must actively opt in to before accessing. This also allows developers to include a trigger warning on the content in question.

Another way to limit exposure is by not indexing the page. According to a paper published by Mozilla, not indexing a page reduces the risk that users will stumble upon it via web search. 

Developers can prevent page indexing by adding a “noindex” metatag. According to Mozilla, this can be done by inserting the following tag in the <head> section of a page’s HTML markup:

<meta name=”robots” content=”noindex”> 

Go above and beyond

Most of what we have discussed focuses on mitigating potentially-risky content. To take things one step further, we ought to weigh the costs and benefits of such risks.

Developers should always ask, “Is this content essential?” When it comes to seizure prevention, this question is paramount.

If animations or GIFs aren’t necessary on a page, it would be best not to include them. Gambling with seizures can lead to harm and legal trouble for developers. 


Reducing seizure risks on content is essential to improving digital accessibility. By following these tips, developers and content creators can ensure the safety and enjoyment of their users.


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