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THE REAL HAT MAN

Diphenhydramine in the United States: what the numbers say

Diphenhydramine (DPH) is the active ingredient in Benadryl and in many store-brand allergy pills and sleep aids. It's cheap, sold without a prescription, and sitting in most medicine cabinets. At high doses it causes anticholinergic delirium, the state this game is about, along with a racing heart, seizures and dangerous heart-rhythm problems.

The Hat Man is folklore. The overdoses are not.

Deaths

Overdose deaths where diphenhydramine was named on the death certificate as involved. It's rarely the only drug: in 2019–2020, 82.7% of diphenhydramine-involved overdose deaths also involved opioids. It is also found in the street drug supply as a cutting agent. But in suicides it often stands alone near the top. In 2023 it was the single drug most often involved in suicide-related overdose deaths, ahead of oxycodone and bupropion.

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Self-harm

It's in the house, it's legal, and nobody thinks of it as dangerous. That's why it shows up in self-harm, especially among young people. US poison centers now report suicidal intent as the leading reason for diphenhydramine cases in children and teens. Those cases more than doubled from 2014 to 2023, and they're more common among girls and adolescents. In that study, about 90% of cases needed treatment at a health care facility and about 20% were admitted to critical care.

Suspected suicide attempts by diphenhydramine self-poisoning among 10–19 year-olds reported to US poison centers. In the first nine months of 2022 the rate ran 35.8% above the same months of 2019. Across all substances, self-poisoning attempts in this age group rose 73% among 10–12 year-olds and 36.8% among girls (2021 vs. 2019).

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An earlier national study (2005–2016) had already found intentional diphenhydramine exposures up 63%, and suicide attempts involving it up 263% among children aged 10–14. Serious outcomes, including cardiac complications, seizures and deaths, were more common in intentional ingestions.

The challenge

In 2020 the "Benadryl challenge" spread on TikTok: take a large amount and film the hallucinations. On September 24, 2020 the FDA warned that high doses of diphenhydramine can cause serious heart problems, seizures, coma or death, and asked TikTok to remove the videos. A 15-year-old in Oklahoma died that August. A 13-year-old in Ohio died in 2023 after six days in intensive care. In early 2026 the Washington Poison Center reported an average of 52 adolescent diphenhydramine cases a month, up from 32 a month in 2025, about one in ten of all its adolescent cases.

The forum

The board in this game is invented, but boards like it exist. One study of r/DPH counted 19,004 authors and 233,028 posts between 2014 and 2022. Researchers describe a community that warns people away from the drug while continuing to use it: dark memes about spiders and the Hat Man sit next to harm-reduction guides, and people say plainly that they use it to escape. Accounts of the trip itself are overwhelmingly unpleasant. Lasting effects reported include memory problems, heart palpitations and worsened depression.

What an overdose looks like

confusion · extreme drowsiness or agitation · hallucinations · large pupils · hot, flushed, dry skin · racing or irregular heartbeat · seizures

If someone took too much, don't wait for it to pass. The game's "wait for morning" is fiction.

Sources

1. NCHS. Drugs Most Frequently Involved in Drug Overdose Deaths: United States, 2017–2023. National Vital Statistics Reports 75(1), March 2026.
2. CFSRE. Diphenhydramine: An Adulterant Found in Illicit Street Drugs. Public health alert, April 2023.
3. CDC MMWR. Notes from the Field: Antihistamine Positivity and Involvement in Drug Overdose Deaths, 44 Jurisdictions, 2019–2020.
4. Farah R, Rege SV, Cole RJ, Holstege CP. Suspected Suicide Attempts by Self-Poisoning Among Persons Aged 10–19 Years During the COVID-19 Pandemic. MMWR 2023;72:426–430.
5. Trends in Pediatric Diphenhydramine Cases Reported to US Poison Centers (2014–2023). Pediatrics Open Science.
6. Increased rates of diphenhydramine overdose, abuse, and misuse in the United States, 2005–2016. Clinical Toxicology 59(11).
7. FDA. FDA warns about serious problems with high doses of the allergy medicine diphenhydramine (Benadryl). September 24, 2020.
8. Benadryl challenge (Wikipedia), for the 2020 and 2023 deaths.
9. Washington Poison Center. Rising Teen Overdoses from Diphenhydramine.
10. Seeing Spiders: A Qualitative Analysis of an Online Community of Recreational Diphenhydramine Users.
11. Funny Pink Pill: The Discourse of Delirium on r/DPH. Synapsis, 2022.
12. The Delirious Cult of Recreational Benadryl Users. MEL Magazine.

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