A study by the Gambling Health Alliance suggests young people are not only regularly spending on loot boxes, but struggling to keep track of how much they have spent.
The organisation, which was established by the Royal Society for Public Health, has released a new report based on a survey of 611 young people from England, Scotland and Wales.
23% of 11 to 16-year-olds said they had paid money to open loot boxes, with 34% of all respondents saying they had first purchased them by the time they were 13, due to the lack of age restrictions on games containing the randomised monetisation mechanic.
The study found that 31% of young gamers say they are unaware of how much they have spent on loot boxes, while 33% say they do now feel in console of their spending.
When asked to estimate how much a loot box costs -- due to the real-money value being obfuscated by virtual currencies -- most estimated purchases to be worth between £1 and £3. However, some reported a single loot box could cost as much as £20.
11% said they purchased loot boxes on a daily or weekly basis, with 27% claiming to spend monthly.
Weekly spenders estimated they would pay as much as £5 per week, or £260 per year, while nearly one in ten gamers said they spent between £11 and £20 per week -- amounting to between £570 and £1,040 per year.
22% of respondents confirmed they had spent over £100 on loot boxes, in addition to the purchase of the game itself.
The report also explored the financial impact on spenders, with 13% claiming their loot box purchases had gotten them into debt, and 15% saying they had taken money from parents without permission.
One person claimed they had resorted to crime to pay of debts, while three said their spending had forced their families to remortgage their homes.
The Gambling Health Alliance released these results during a campaign to have loot boxes reclassified as gambling -- something the Royal Society for Public Health also called for with a similar report last year.
The UK government recently closed a call for evidence around loot boxes ahead of a review for the nation's gambling laws.
The report particularly draws attention to the lack of age restrictions and in-game spending trackers, although notes that EA has now added the latter system with FIFA Playtime to help Ultimate Team users keep on top of their purchases. It also introduces family controls to limit spending.
"This is a welcome step in the right direction," the report said. "We believe that protective measures like this should be introduced across all games containing loot boxes until they are recognised as gambling and removed from games played by under-18s."
According to the survey, 79% of respondents who played FIFA said Ultimate Team's loot boxes negatively impacted their experience of the game.
Reasons ranged from the amount they felt they had to spend to play competitively, the poor odds for getting valuable players, and having to start over with each new release of FIFA.
Following the launch of FIFA Playtime, our own Brendan Sinclair explored the problematic situation EA and FIFA are in, with Ultimate Team under intense scrutiny but delivering more than a quarter of the publisher's revenues in the last fiscal year.