The European Commission has accused TikTok of creating an "addictive design" in its app which could harm the physical and mental wellbeing of minors and vulnerable adults.
It said the platform had been guilty of "multiple" violations of the EU's Digital Services Act (DSA).
The commission said the addictive design included infinite scroll features, autoplay, push notifications, and a highly personalised "recommender system", which uses AI to predict the preferences or ratings a user would give a product.
Officials said the recommender system was designed only to increase time spent on the app, and not to take account of negative experiences that a teenage user might have.
The app constantly rewarded users with new content, thus fuelling the urge to keep scrolling and to "shift the brain of users into 'autopilot mode’," said the commission.
This could lead to compulsive behaviour and reduce users' self-control.
In a statement, the commission claimed TikTok "did not adequately assess how these addictive features could harm the physical and mental wellbeing of its users, including minors and vulnerable adults."
The tech firm had also "disregarded important indicators of compulsive use of the app, such as the time that minors spend on TikTok at night, the frequency with which users open the app, and other potential indicators."
The commission said TikTok had failed to implement "reasonable, proportionate and effective measures" to mitigate risks stemming from its addictive design.
Screentime management and parental control tools had not effectively reduced the risks stemming from TikTok’s addictive design, the commission said.
"The time management tools do not seem to be effective in enabling users to reduce and control their use of TikTok because they are easy to dismiss and introduce limited friction," the commission said.
The investigation, launched in February 2024, also covered the so-called "rabbit hole effect" when using TikTok, as well as the risk of minors being exposed to inappropriate content if they misrepresented their age.
Watch: European Commission says aspects of TikTok could lead users to infinite scrolling, reports Tony Connelly
The commission said TikTok should disable key addictive features such as "infinite scroll" over time, and implement effective screen-time breaks, including after midnight.
The preliminary findings do not prejudge the outcome of the overall investigation, said the statement.
The commission said its conclusions were based on an analysis of TikTok's risk assessment reports, internal data and TikTok's responses to "multiple requests for information", as well as a review of the recent scientific research and interviews with experts in multiple fields, including behavioural addiction.
TikTok can now challenge the preliminary finding by consulting the commission's investigation documents, and can reply in writing.
If the preliminary finding is upheld, TikTok could face a fine worth up to 6% of its global annual turnover.
Senior EU officials said there was growing evidence of TikTok users using the app after midnight, citing expertise that more and more 12-15 year olds were spending "too much time" on TikTok.
The commission said there should be mandatory screen time limits and lock-outs at night "to avoid sleep deprivation".
Officials said that combatting behavioural addiction by minors was a mandatory component of the assessment of the risks, and that TikTok had ignored widespread evidence.
"TikTok did not properly assess these risks…and did not properly mitigate these mental health risks on its platforms … TikTok disregarded relevant evidence on excessive use of its platforms," said a senior EU official.
The commission said it based its investigation on a range of publicly available studies and expertise.
It included a French parliamentary report that showed 8% of 12-15 year-olds spending more than five hours on TikTok, a Danish study mentioning users as young as eight using it on average more than two hours per day, and a Polish study where TikTok was cited as the most used platform after midnight by 13-18 year-olds.
Officials said there had been multiple failures by TikTok to take such evidence into account.
News at One: TikTok videos are 'really addictive', says Athlone residents
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
"There's a general rule in the DSA that the best scientific evidence and expert knowledge have to be taken into account when assessing these risks," said an EU official. "We found really serious shortcomings in the system, and not just in one risk assessment report but in multiple ones."
Officials suggested TikTok’s business model linked advertising income to keeping users on the platform as long as possible.
"It's not fundamentally impossible to add friction to the system to make these mitigations effective. And indeed, in the [DSA] guidelines there is rich material on how some of this can be mitigated," said an official.
Despite the preliminary finding, the commission said TikTok had been cooperative throughout the investigation and had come forward with ideas.
Officials denied the finding amounted to censorship.
"The DSA … is not a content law, and it is building on freedom of expression. It is a due diligence tool to deal with systemic risks, and it is not censorship," said an official.
'Categorically false' depiction of platform, says TikTok
A TikTok spokesperson said: "The commission's preliminary findings present a categorically false and entirely meritless depiction of our platform, and we will take whatever steps are necessary to challenge these findings through every means available to us."
According to the company, the platform offered numerous tools, from daily screen time limits to sleep reminders which prompt users to close TikTok for the night, and offer an interactive meditation experience and silencing notifications.
The company also says there are screen time breaks and an in-app screen time dashboard with easily accessible information about how people spend time on TikTok.
There were also "well-being missions" that provided badges for those who stayed off TikTok at night and who meditated during sleep hours.
Users could also earn daily screen time "badges" by setting a screen-time limit and then sticking to their goal.
TikTok argues there is no scientific consensus on the impact of screentime and as such the company was focused on empowering users to make their own choice.
The company quoted a UNICEF study from 2025 that stated "we find no clear evidence that screen time directly harms children's mental health. Although increased screen time can sometimes be associated with a higher risk of exposure to harmful content and abusive experiences, the effect is weak.
"This suggests that the likelihood of encountering online harm is not primarily determined by the amount of time spent online."
The company says accounts belonging to 13-17 year-olds had their screen time set to 60 minutes automatically and that parents could use "Family Pairing" to further restrict access and time spent on the platform.
It says that once a parent set a screen time limit, teens are unable to switch to a different account or log out.
TikTok says if 13-17 year-olds used TikTok after 10pm, their "For You" feed is interrupted with a guided meditation experience designed to help them to wind down and switch off for the evening.
A more robust prompt followed if teens decided to spend additional time on TikTok after the first reminder.
The company says 13-15 year-olds do not receive push notifications from 9pm and those aged 16-17 have notifications disabled from 10 pm.
The Taoiseach has described the interim findings of the European Commission's investigation as very serious.
Speaking in Cork, Micheál Martin said the preliminary findings vindicate the actions taken by the Government to restrict access to smart phones in schools through the use of pouches.
"I think these are very serious interim findings by the European Commission," he said.
"Our priority has to be the protection of young people and children, and their mental health in particular, and these findings indicate that quite a number of the algorithms have a lack of protection of young people in particular.
"I think it vindicates the decision we took last year to ban the use of smart phones in primary schools and we brought in the pouches which was criticised by the Opposition at the time, but we were right to do that."
Mr Martin was speaking at the opening of expanded offices in Cork for the professional services company EY.
Additional reporting Paschal Sheehy
