Benadryl Overdose: Signs, Dangers, and What to Do
What a Benadryl (diphenhydramine) overdose is, the warning signs, why it is dangerous, the risk to children and from the online Benadryl Challenge, and what to do in an emergency.
Clinically reviewed by Dr. Ponlawat Pitsuwan, Physician and Addiction Medicine Specialist, Phuket Island Rehab.
A Benadryl overdose happens when someone takes too much diphenhydramine, the active ingredient in Benadryl, a common over-the-counter antihistamine used for allergies and, in some products, to aid sleep. Although Benadryl is widely available and safe at normal doses, taking too much can be dangerous and even fatal. Signs of a Benadryl overdose include severe drowsiness or agitation, confusion, blurred vision, dilated pupils, dry mouth, flushed skin, a fast or irregular heartbeat, difficulty urinating, hallucinations, and, in serious cases, seizures, an abnormal heart rhythm, loss of consciousness, and death. Overdose is a particular danger in young children, who are more sensitive to the drug, and it has also been linked to the so-called Benadryl Challenge, a dangerous online trend encouraging people to take large amounts to get high or hallucinate, which has caused serious harm and deaths. A Benadryl overdose is a medical emergency: if you suspect one, call your local emergency number or a poison control centre immediately. Because Benadryl is sometimes misused for its sedative or hallucinogenic effects, repeated misuse can also become a pattern that needs help. If misuse is a concern, support and treatment are available.
What is a Benadryl overdose?
Benadryl is a widely used brand of medication whose active ingredient is diphenhydramine, an antihistamine. It is available over the counter and is commonly used to relieve allergy symptoms such as hay fever, itching, and reactions, and, because it causes drowsiness, diphenhydramine is also used in some products as a sleep aid. A Benadryl overdose occurs when a person takes more diphenhydramine than the body can safely handle, whether accidentally or deliberately. Although Benadryl is generally safe and effective when used at the recommended dose, it is a genuine drug with real effects on the body, and taking too much can be dangerous and, in serious cases, fatal. The fact that it is available without a prescription can create a false impression that it is harmless in any amount, but this is not the case: like many medicines, diphenhydramine is safe within its proper dose range and harmful in excess.
This article explains what a Benadryl overdose is, the warning signs to look for, why an overdose is dangerous, the particular risks to young children and from the online Benadryl Challenge, and what to do in an emergency. The central message is that while Benadryl is a common and useful medicine at normal doses, taking too much diphenhydramine is a serious matter that can cause dangerous effects on the heart, brain, and nervous system and can be life-threatening, and that a suspected overdose is a medical emergency requiring immediate help. It is also important to be aware that diphenhydramine is sometimes deliberately misused, including by young people influenced by dangerous online trends, and that repeated misuse can become a pattern that needs support. Knowing the signs of a Benadryl overdose and what to do could save a life.
Signs of a Benadryl overdose
The signs of a Benadryl overdose come from the effects of too much diphenhydramine on the body, and they can include a mix of sedative and stimulating effects. Common signs include severe drowsiness and sedation, but paradoxically also agitation, restlessness, and excitability (especially in children), along with confusion, disorientation, and difficulty thinking clearly. Diphenhydramine also has what are called anticholinergic effects, which produce a recognisable pattern of signs: dilated (enlarged) pupils, blurred vision, dry mouth, flushed and dry skin, a raised body temperature, a fast heartbeat, and difficulty passing urine. People may also experience nausea, and in more significant overdoses, hallucinations (seeing or hearing things that are not there), which is one reason diphenhydramine is misused to get high, though these experiences can be frightening and are a sign of a dangerous level of the drug.
In more serious overdoses, the signs become more dangerous and can include severe confusion or delirium, a very fast or irregular heartbeat and abnormal heart rhythms (which can be life-threatening), very high body temperature, muscle problems, seizures (fits), a dangerously low level of consciousness, coma, and, in the worst cases, death. The effects on the heart’s rhythm and the risk of seizures are among the most dangerous aspects of a large diphenhydramine overdose. It is important to understand that the amount required to cause an overdose varies with body size and individual factors, and that children are much more sensitive than adults, so a smaller amount can be dangerous for a child. Because the signs range from drowsiness and confusion to seizures and heart problems, any suspicion that someone has taken too much Benadryl should be treated seriously and as a potential medical emergency. Recognising these warning signs is the first step to getting help quickly.
| Severity | Signs |
|---|---|
| Common | Severe drowsiness, agitation, confusion, dry mouth |
| Anticholinergic | Dilated pupils, blurred vision, flushed skin, fast heartbeat |
| Difficulty | Difficulty urinating, raised temperature, nausea |
| More serious | Hallucinations, delirium, seizures, abnormal heart rhythm |
| Severe | Loss of consciousness, coma, death |
| Higher risk | Young children; misuse via the ‘Benadryl Challenge’ |
Why it is dangerous: children and the Benadryl Challenge
A Benadryl overdose is dangerous because, in large amounts, diphenhydramine can seriously disrupt the heart, brain, and nervous system. The most life-threatening effects are on the heart, where a large overdose can cause dangerous, abnormal heart rhythms, and on the brain and nervous system, where it can cause seizures and loss of consciousness. These effects can be fatal. Two groups and situations deserve particular attention. The first is young children, who are much more sensitive to diphenhydramine than adults, so that an amount that would be modest for an adult can be dangerous or even fatal for a small child. Accidental overdose in children can happen if medicine is left within reach or if doses are miscalculated, which is why Benadryl and all medicines should be stored safely out of children’s reach and given to children only in the correct, age-appropriate dose (and, for very young children, only on medical advice).
The second is the so-called Benadryl Challenge, a dangerous trend that has circulated on social media, encouraging young people to take large amounts of diphenhydramine deliberately in order to get high or experience hallucinations. This is extremely dangerous: taking the large doses involved can cause exactly the serious overdose effects described, including seizures, dangerous heart rhythms, and death, and there have been reports of serious harm and fatalities linked to this challenge. Diphenhydramine is also sometimes misused by individuals seeking its sedative or hallucinogenic effects outside of any online trend. Any deliberate misuse of Benadryl to get high carries a real risk of a life-threatening overdose, because the margin between the dose that produces the sought-after effects and the dose that causes dangerous toxicity can be narrow, and the hallucinations and delirium are themselves signs of dangerous toxicity. Awareness of these dangers, especially among young people and parents, is important, and it underlines why Benadryl, despite being an everyday medicine, must be respected and used only as directed.
What to do and getting help
A Benadryl overdose is a medical emergency, and quick action is important. If you suspect that someone has taken too much diphenhydramine, whether a child who has got into medicine, a person who has taken an overdose deliberately, or someone showing the signs described, seek help immediately: call your local emergency number, or contact a poison control centre for guidance (in the US, Poison Control can be reached at 1-800-222-1222). Do not wait for symptoms to become severe. If the person is unconscious, having a seizure, or having difficulty breathing, call the emergency number straight away. Try to find out how much was taken and when, and keep the medicine packaging to show medical staff, as this helps treatment. Do not try to make the person vomit unless specifically told to by a medical professional. In hospital, an overdose can be treated with supportive care and specific measures depending on the situation, and outcomes are best when help is sought early.
Beyond the immediate emergency, if a Benadryl overdose was deliberate, it is important to address what led to it. If it was an attempt to self-harm or was linked to emotional distress, mental health support is essential, and anyone who has harmed themselves or is having thoughts of suicide needs prompt, compassionate help. If it was part of misusing diphenhydramine to get high, whether influenced by an online challenge or otherwise, this is a sign that support may be needed, especially if such misuse is repeated. While diphenhydramine is not addictive in the same way as some drugs, repeated misuse of it or other substances to alter mood or escape can be part of a wider pattern that benefits from help. Support and treatment are available for substance misuse and for the underlying difficulties that may drive it. The key messages are that Benadryl is safe at normal doses but dangerous in overdose, that overdose is a medical emergency requiring immediate help, that children and those misusing it deliberately are at particular risk, and that if misuse or self-harm is involved, reaching out for professional help is important and support is available.
Summary
A Benadryl overdose happens when someone takes too much diphenhydramine, the active ingredient in Benadryl, a common over-the-counter antihistamine used for allergies and, in some products, to aid sleep. Although Benadryl is widely available and safe at normal doses, taking too much can be dangerous and even fatal. Signs of a Benadryl overdose include severe drowsiness or agitation, confusion, blurred vision, dilated pupils, dry mouth, flushed skin, a fast or irregular heartbeat, difficulty urinating, hallucinations, and, in serious cases, seizures, an abnormal heart rhythm, loss of consciousness, and death. Overdose is a particular danger in young children, who are more sensitive to the drug, and it has also been linked to the so-called Benadryl Challenge, a dangerous online trend encouraging people to take large amounts to get high or hallucinate, which has caused serious harm and deaths. A Benadryl overdose is a medical emergency: if you suspect one, call your local emergency number or a poison control centre immediately. Because Benadryl is sometimes misused for its sedative or hallucinogenic effects, repeated misuse can also become a pattern that needs help. If misuse is a concern, support and treatment are available.
As Dr. Ponlawat Pitsuwan, addiction medicine specialist at Phuket Island Rehab, puts it, “Because Benadryl sits on every shelf and needs no prescription, people assume it cannot really hurt you. But diphenhydramine in large amounts is a genuinely dangerous drug: it can throw the heart into abnormal rhythms and trigger seizures, and it can kill. Two things worry me most. One is small children getting into it, because they are so much more sensitive. The other is the online challenges that dare teenagers to take huge doses to hallucinate, when those very hallucinations are a warning sign of toxicity. If you ever suspect an overdose, do not wait, call emergency services or poison control at once. And if it was deliberate, that is a signal the person needs support, which we can provide.”
Frequently asked questions
How much Benadryl is an overdose?
There is no single number that applies to everyone, because the amount of diphenhydramine that causes an overdose depends on factors such as body size, age, individual sensitivity, and whether other substances are involved. What is clear is that taking more than the recommended dose on the packaging (or more than a doctor has advised) risks harm, and that significantly exceeding the normal dose can cause a dangerous overdose. Children are much more sensitive than adults, so a smaller amount can be dangerous for a child, which is why doses for children must be age- and weight-appropriate and why medicines must be kept out of their reach. Rather than trying to work out an exact overdose threshold, the safest approach is to always follow the dosing instructions, never take extra to increase the effect or to get high, and treat any suspected overdose seriously. If you think someone has taken too much Benadryl, do not try to judge whether the amount is dangerous yourself; contact a poison control centre or emergency services for guidance, as they can advise based on the specifics.
What are the signs of taking too much Benadryl?
Signs of taking too much Benadryl (diphenhydramine) include severe drowsiness and sedation, but also, paradoxically, agitation, restlessness, and excitability (especially in children), along with confusion and disorientation. Diphenhydramine’s anticholinergic effects produce a recognisable pattern: dilated pupils, blurred vision, dry mouth, flushed dry skin, raised body temperature, a fast heartbeat, and difficulty passing urine. People may also have nausea, and in more significant overdoses, hallucinations. In serious overdoses, the signs become more dangerous and can include severe confusion or delirium, a very fast or irregular heartbeat and abnormal heart rhythms, very high body temperature, seizures, a dangerously low level of consciousness, coma, and death. Because the signs range from drowsiness and confusion to seizures and heart problems, any suspicion that someone has taken too much Benadryl should be treated as a potential medical emergency. If you notice these signs after someone has taken Benadryl, seek help immediately by calling a poison control centre or your local emergency number.
What is the Benadryl Challenge?
The Benadryl Challenge is a dangerous trend that has circulated on social media, encouraging people, often young people and teenagers, to take large amounts of diphenhydramine (Benadryl) deliberately in order to get high or experience hallucinations. It is extremely dangerous. Taking the large doses involved can cause a serious overdose, with effects including seizures, dangerous abnormal heart rhythms, delirium, loss of consciousness, and death, and there have been reports of serious harm and fatalities linked to this challenge. The hallucinations that the challenge encourages people to seek are themselves a sign of dangerous toxicity, not a safe recreational effect. The margin between the dose that produces these effects and the dose that causes life-threatening toxicity can be narrow. Parents, carers, and young people should be aware of this trend and its dangers. If you know someone who has attempted the Benadryl Challenge and shows any signs of overdose, treat it as a medical emergency and seek help immediately. More broadly, deliberate misuse of Benadryl to get high is a sign that support may be needed, and help is available.
Is a Benadryl overdose dangerous?
Yes, a Benadryl overdose can be very dangerous and even fatal. Although Benadryl is safe at normal doses, in large amounts diphenhydramine can seriously disrupt the heart, brain, and nervous system. The most life-threatening effects are dangerous, abnormal heart rhythms and seizures, along with loss of consciousness, and these can lead to death. Other serious effects include severe confusion or delirium, very high body temperature, and coma. Young children are at particular risk because they are much more sensitive to diphenhydramine, so a relatively small amount can be dangerous for them. Deliberate large overdoses, such as those linked to the Benadryl Challenge or to misuse for hallucinogenic effects, are especially dangerous. Because of all this, a suspected Benadryl overdose should always be treated as a medical emergency, and help should be sought immediately from a poison control centre or emergency services. The everyday availability of Benadryl can create a false sense that it is harmless in any amount, but taking too much is a genuine and serious danger.
Can you get addicted to Benadryl?
Diphenhydramine (Benadryl) is not considered addictive in the same way as substances like opioids or benzodiazepines, and it does not typically cause the strong physical dependence and cravings associated with those drugs. However, some people do misuse Benadryl, using it repeatedly for its sedative effects (for example to sleep) or, in larger amounts, for its hallucinogenic effects, and a pattern of relying on it or misusing it can develop. Using diphenhydramine regularly as a sleep aid can also lead to a degree of tolerance and a psychological reliance on it for sleep, and long-term regular use of anticholinergic medicines has other health considerations, so it is best used short-term and as directed. More importantly, repeated misuse of Benadryl to get high or to escape, whether or not it meets a strict definition of addiction, is a sign that support may be needed, and it carries the serious risk of overdose. If you or someone you know is misusing Benadryl, or relying on it in a way that is concerning, it is worth seeking advice, and support and treatment for substance misuse and any underlying difficulties are available.
What should you do if you suspect a Benadryl overdose?
If you suspect a Benadryl overdose, treat it as a medical emergency and act quickly. Call your local emergency number, or contact a poison control centre for guidance (in the US, Poison Control: 1-800-222-1222). Do not wait for symptoms to become severe. If the person is unconscious, having a seizure, or having difficulty breathing, call emergency services straight away. Try to find out how much diphenhydramine was taken and when, and keep the medicine packaging to show medical staff, as this helps guide treatment. Do not try to make the person vomit unless specifically instructed to by a medical professional. If the person is unconscious but breathing, place them on their side in the recovery position while waiting for help. In hospital, a Benadryl overdose is treated with supportive care and specific measures depending on the situation, and outcomes are best when help is sought early. If the overdose was deliberate self-harm, the person will also need mental health support afterwards. Acting fast and seeking professional guidance is the most important thing you can do.
Sources
National Library of Medicine (MedlinePlus). Diphenhydramine. https://medlineplus.gov/druginfo/meds/a682539.html
U.S. Food and Drug Administration (FDA). Benadryl (Diphenhydramine) Safety Warning. https://www.fda.gov/drugs/drug-safety-and-availability
America’s Poison Centers. Poison Control. https://www.poison.org/
National Library of Medicine (MedlinePlus). Diphenhydramine Overdose. https://medlineplus.gov/ency/article/002607.htm
Substance Abuse and Mental Health Services Administration (SAMHSA). Substance Use. https://www.samhsa.gov/
Centers for Disease Control and Prevention (CDC). Medication Safety. https://www.cdc.gov/medication-safety/
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