Benadryl sits on almost every bathroom shelf in America. It treats allergies, calms a runny nose, and helps some people sleep. So when a parent learns that their teenager has been taking it by the handful to feel high, the first reaction is usually disbelief. How can an allergy pill be dangerous? The honest answer is that diphenhydramine, the drug inside Benadryl, becomes a different and far riskier substance once you push past the dose on the label. For a young person who is already struggling with anxiety, depression, or the kind of restlessness that has no name yet, that risk gets sharper.
What Is Benadryl and How Does It Work?
Diphenhydramine, sold under the brand name Benadryl, is a first-generation antihistamine used to relieve allergies, hay fever, and cold symptoms. It blocks histamine, the chemical your immune system releases during an allergic reaction. It also crosses into the brain and blocks acetylcholine, a neurotransmitter tied to alertness and memory, which is why it makes most people drowsy. Taken as directed, it’s a safe, effective medication that’s been on shelves for decades.
The trouble starts when someone takes much more than the label allows. At high enough doses, diphenhydramine stops acting like a sleep aid and starts producing hallucinations and a sense of being detached from one’s own body. That effect is the whole point of the misuse, and it’s also where the medical danger lives.
What Does the FDA Say About High Doses of Benadryl?
On September 24, 2020, the FDA issued a drug safety communication warning that taking higher than recommended doses of diphenhydramine can lead to serious heart problems, seizures, coma, and death. The agency acted after news reports of teenagers landing in emergency rooms, and in some cases dying, after taking part in a social media dare known as the “Benadryl Challenge.” The FDA warning tells anyone who suspects an overdose, signs include hallucinating, not being able to wake the person, seizures, or trouble breathing, to seek emergency care and contact Poison Control at 1-800-222-1222 right away.
That warning matters because of how the body responds to a large dose. Diphenhydramine in overdose produces what clinicians call an anticholinergic toxidrome. According to StatPearls, published through the National Library of Medicine, the picture can include a racing heart, dilated pupils, urinary retention, flushed dry skin, and a dangerously high body temperature. As the dose climbs, so does the risk to the brain and heart.
What Are the Effects and Dangers of Benadryl Misuse?
People who misuse diphenhydramine are chasing euphoria, vivid hallucinations, and that out-of-body feeling. What comes with it is a long list of effects that range from miserable to fatal. Common reactions include:
- Drowsiness, dizziness, and blurred vision
- A fast or irregular heartbeat
- Nausea, vomiting, and constipation
- Confusion, memory problems, and trouble thinking clearly
- Agitation, delirium, psychosis, and seizures
At the high end, the danger is the heart. In severe overdose, diphenhydramine blocks sodium channels in the heart muscle, which can trigger a wide-complex tachycardia and other arrhythmias documented in case reports indexed by the National Library of Medicine. Combined with seizures, very high body temperature, and coma, that’s how a Benadryl overdose becomes deadly. The 2020 FDA communication named seizures, serious heart problems, coma, and death as the outcomes families need to take seriously.
There’s a longer-term question too, though it applies to a different group of people. A 2015 prospective study in JAMA Internal Medicine followed adults age 65 and older and found that higher cumulative use of strong anticholinergic drugs, diphenhydramine among them, was associated with a greater risk of dementia. The study showed correlation, not proof of cause, and it described years of regular use in older adults rather than the binge pattern seen in younger misuse. It’s a reason to be cautious about leaning on Benadryl as a nightly habit, separate from the acute danger of getting high on it.
Why Does Benadryl Appeal to Teens?
A few things make diphenhydramine an easy target for experimentation. It’s cheap and sold over the counter at nearly every drugstore and supermarket, so there’s no dealer and no real barrier. Because it’s a legal medicine with legitimate uses, a lot of teens assume it must be safer to abuse than an illegal drug, which is exactly backward at high doses. The hallucinations and dissociation it produces are the draw, and those experiences have been packaged and spread on social media.
The “Benadryl Challenge” is the clearest example. A case report in the Journal of Forensic Sciences, indexed in PubMed, documented the death of a 14-year-old girl who took a massive dose of diphenhydramine while taking part in the trend, with a blood concentration far above the lethal range. Poison centers around the country have linked rising teen calls about diphenhydramine to these online dares. The drug isn’t new. The way it spreads is.
What Are the Signs of Benadryl Misuse?
If you’re worried about your child or someone you love, a few patterns are worth watching for:
- Taking large amounts of the drug on a regular basis, or empty boxes turning up
- Needing higher and higher doses to feel anything
- Spending unusual time or money getting it
- Letting school, work, or responsibilities slide
- Pulling away from friends and family, or noticeable mood changes
Here’s the part that often gets missed. Reaching for a substance over and over, even one as ordinary as an allergy pill, is frequently a sign that something underneath is unmanaged. Anxiety, depression, trauma, and the disorienting pull of adolescence can all push a young person toward anything that quiets the noise for an hour. That’s why treating the misuse alone rarely holds.
How Is Benadryl Misuse Treated?
At Destination Hope, we treat mental health as the primary condition, with substance misuse addressed as part of the same clinical picture rather than as a separate problem to fix later. When someone is using diphenhydramine to escape, the question isn’t only how to stop the use. It’s what the use is doing for them, and what would have to change for them not to need it. Our psychiatrist-led team starts with a comprehensive evaluation to understand the full picture, including any co-occurring depression, anxiety, or trauma driving the behavior.
From there, care is built around the individual. That can include on-site medical support, medication management where it’s appropriate, and evidence-based therapy such as CBT and DBT to work on the root cause, not only the symptom. For people whose mental health and substance use are tangled together, our dual diagnosis treatment program treats both at once so neither gets left behind. You can read more about our broader addiction treatment approach and how it fits inside primary psychiatric care.
If your teenager or someone you love is misusing Benadryl, you don’t have to figure out the next step on your own. Our team is available 24/7 to talk through what’s happening and what real help looks like. Reach out through our admissions team or call Destination Hope at (954) 302-4269.
Crisis and Emergency Resources
If you or someone you know is in a substance use or mental health crisis, help is available now. Contact the SAMHSA National Helpline at 1-800-662-HELP (4357) for free, confidential treatment referrals 24/7. Reach the 988 Suicide and Crisis Lifeline by calling or texting 988. The Crisis Text Line is available by texting HOME to 741741. For emergencies, call 911.
