People abuse Benadryl (diphenhydramine) primarily to induce hallucinations. At doses far above the recommended 25 to 50 mg, typically exceeding 300 mg, the drug overwhelms the brain’s signaling system and produces a delirious, hallucinatory state that some users seek out recreationally. The behavior is most common among teenagers, fueled in part by social media trends, and it carries serious risks including seizures, dangerous heart rhythms, and death.
What Happens in the Brain at High Doses
At normal doses, diphenhydramine blocks histamine receptors to reduce allergy symptoms and cause drowsiness. But the drug also crosses easily into the brain and blocks receptors for acetylcholine, a chemical messenger involved in memory, attention, and perception. At therapeutic doses, this produces familiar side effects like grogginess and forgetfulness. At massively elevated doses, the disruption to acetylcholine becomes severe enough to cause delirium and vivid hallucinations.
This type of hallucination is fundamentally different from what psychedelics produce. Rather than enhanced colors or geometric patterns, anticholinergic delirium tends to involve realistic but fabricated scenarios: seeing people who aren’t there, hearing conversations, or interacting with objects that don’t exist. Users frequently can’t distinguish these experiences from reality. The state is closer to a waking nightmare than a recreational high, and many people who’ve experienced it describe it as deeply unpleasant and frightening.
Why Teenagers Are Most Affected
A study analyzing poison center data from 2014 to 2023 found that 92.6% of pediatric diphenhydramine cases involved adolescents aged 13 to 19. Female individuals accounted for 72.3% of reported cases. These numbers reflect two overlapping patterns: social media influence and self-harm.
The so-called “Benadryl Challenge” emerged on TikTok in May 2020, encouraging users to take ten or more times the normal dose to film themselves hallucinating. The first challenge-related hospitalization was reported that same month. Although attention to the trend faded, it resurfaced in 2023, which saw the highest number of reported cases (73 in that year alone, up from single digits in earlier years). The trend’s persistence highlights a core problem: the drug is cheap, legal, available in every pharmacy, and sits in most household medicine cabinets.
But social media challenges account for only part of the picture. Suicidal intent was the leading reason for diphenhydramine ingestion among adolescents, more than doubling over the study period. By 2021, one year after the pandemic began, 82.5% of cases involved suicidal intent. This means the majority of serious diphenhydramine misuse among young people isn’t thrill-seeking. It’s a mental health crisis playing out through an easily accessible drug.
Other Reasons People Misuse It
Beyond the hallucinations and social media trends, some people take excessive Benadryl for more mundane reasons that gradually escalate. The drug’s sedating effects make it appealing as a sleep aid, and tolerance builds quickly, leading some users to increase their dose over weeks or months. Others combine it with alcohol or opioids to amplify sedation, which dramatically increases the risk of respiratory depression.
A smaller number of people use it to self-medicate anxiety. The drowsiness and mental fog can feel like temporary relief from racing thoughts, creating a pattern of repeated use that becomes difficult to break. Because it’s sold over the counter, there’s a false sense of safety. Many users assume that a drug available without a prescription can’t be truly dangerous.
Why It’s More Dangerous Than People Expect
The gap between a normal dose and a toxic dose is narrower than most people realize. The standard adult dose is 25 to 50 mg. Toxicology guidelines flag any ingestion of 300 mg or more (or 7.5 mg per kg of body weight) as requiring emergency evaluation. That’s as few as 12 standard tablets.
At toxic doses, diphenhydramine doesn’t just affect the brain. It blocks sodium channels in the heart, producing the same type of electrical disturbances seen with certain cardiac medications in overdose. This can cause rapid or irregular heartbeats, and in severe cases, fatal arrhythmias. Few people die from antihistamine overdose overall, but serious heart rhythm disturbances are the primary cause when death does occur.
Neurological effects at high doses include seizures, loss of consciousness, and respiratory depression. In the worst outcomes, prolonged seizures or oxygen deprivation can cause permanent brain damage. The combination of cardiac and neurological toxicity makes diphenhydramine overdose unpredictable. Some people tolerate a high dose with only confusion and agitation, while others develop life-threatening complications from a similar amount.
Dependency and Withdrawal
Diphenhydramine doesn’t produce the intense physical dependence associated with opioids or benzodiazepines, but chronic high-dose use does create a withdrawal syndrome. Within one to three days of stopping, users may experience dizziness, nausea, vomiting, headaches, and anxiety. These symptoms are usually mild but can persist for six to eight weeks in some cases.
Rarely, withdrawal produces more serious effects including rapid heart rate, drops in blood pressure upon standing, severe insomnia, and intense anxiety. The drawn-out timeline surprises many people who assumed an over-the-counter antihistamine couldn’t produce lasting effects after stopping. For chronic users, a gradual taper is generally more manageable than abrupt cessation.
Why It Remains So Accessible
Diphenhydramine is subject to child-resistant packaging requirements when a single package contains more than 66 mg of the drug, meaning virtually all retail packages require safety closures. But there are no purchase limits, age restrictions, or quantity caps like those applied to pseudoephedrine (the decongestant kept behind pharmacy counters due to methamphetamine production concerns).
The packaging rules were designed to prevent accidental poisoning in small children, not to deter intentional misuse by teenagers or adults. A person can buy multiple packages from different stores or order them online with no oversight. This regulatory gap, combined with the drug’s widespread household presence and the perception that over-the-counter means safe, creates the conditions for ongoing misuse. Johnson & Johnson, the maker of Benadryl, updated its packaging with warnings after the TikTok challenge gained attention, but the fundamental accessibility of the drug hasn’t changed.