A dangerous social media trend that started in 2020 has persisted into 2026, with heartbreaking consequences.

In May and June 2026, four American teens died participating in the “Benadryl Challenge.” This trend encourages adolescents and young adults to consume excessive amounts of diphenhydramine – the active ingredient in Benadryl – to induce hallucinations.

One study has estimated that this challenge may have been responsible for as many 131 deaths in the U.S. between 2020 and 2024.

As with all online trends, the Benadryl Challenge is not limited by geographical borders. Though it originated in the U.S., public health officials in Canada have been warning parents and clinicians about the same trend since it began.

I research the powerful effects of social media on health behaviors such as substance use, sexual health and nutrition. The speed at which online trends like the Benadryl Challenge spread presents a new challenge for public health.

The science behind diphenhydramine overdose

Diphenhydramine is marketed under various brand names and is available over the counter as a treatment for allergies in numerous countries. The drug works by blocking a neurotransmitter called acetylcholine, which can help calm the body’s response to allergens.

Although therapeutic doses are generally safe, taking too much can result in severe........

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