A new social media challenge has prompted warnings participants could experience serious side-effects or even die.
Benadryl, a common-over-the-counter allergy medication, is the subject of a new TikTok "challenge" where teenagers take dangerously high doses in an attempt to hallucinate.
The US Food and Drug Administration is investigating the death of an Oklahoma teen in relation to the challenge, as well as the hospitalisations of others.
"We are investigating these reports and conducting a review to determine if additional cases have been reported," the agency said in a news release.
It has contacted TikTok about the challenge and "strongly urged" it remove any Benadryl Challenge posts.
Too much Benadryl can cause severe health problems, including serious heart problems, seizures, coma and death.
TikTok allows users to upload short videos and has been criticised for it's lax safety measures. Recently, a video of a man committing suicide was widely shared across the app, sparking warnings from the Mental Health Foundation.
In February another "challenge" caused serious injuries to young people attempting it. The "skull-breaker challenge" involved two people tricking a third person into jumping into the air and then kicking their feet out from under them.
US student Kathleen DeJesus, 13, had to stay in hospital for two days with a severe concussion after being targeted. She told ABC News she was screaming for an ambulance after the incident happened at her Massachusetts school.
"I was thinking, 'Oh my God, I'm going to lose my life over this game.' I should have never done it."