Some users of over-the-counter melatonin supplements are getting a lot more of that sleep aid than they bargained for. 

A new study out in the Journal of the American Medical Association looked at 25 melatonin gummies and found that 22 were mislabeled. Most contained much more melatonin than advertised. One contained 347% of the labeled amount, while a few contained no detectable melatonin at all. 

The study focused on melatonin gummies for a reason, said co-author Pieter Cohen with the Cambridge Health Alliance. 

“It seemed to us something that a child might get into,” he said — or that parents might give their kids to help them sleep. 

Cohen said something around 5 milligrams of melatonin is perfectly safe for a small child. The problem, according to him, “Personally, I wouldn’t be confident that the amount of melatonin listed on the label is in the product.”

“This is one of those drop-the-mic revelations,” said Christine Whelan, who studies the wellness industry at the University of Wisconsin-Madison. 

She said the supplement industry has boomed during the pandemic, and many consumers assume that the products they’re buying have been tested for safety and efficacy. 

However, the FDA can only investigate complaints after supplements are already on the market. 

“When you’re spending money on something that you don’t know what it is, you’re taking a risk,” Whelan said.

That includes not just a health risk, she said, but a financial one if you’re not getting what you paid for.