Benadryl®: Side effects, interactions, and overdose
The bottom line
Benadryl® (diphenhydramine) is an antihistamine used mostly to treat seasonal allergies. In overdose, diphenhydramine can cause excessive sleepiness, confusion, hallucinations, fast heartbeat, seizures, and coma. Take Benadryl® as directed by a pharmacist or physician to avoid unwanted side effects.
Prevention Tips
Store medications up, away, and out of sight of children.
Educate children and teens that viral social media “challenges” can be very dangerous .
Take medicine as directed on the label.
This Really Happened
A 14-year-old girl was taken to an emergency room due to a diphenhydramine overdose caused by participation in a TikTok™ social media challenge. She was given supportive care and was subsequently admitted to a psychiatric facility for 7 days. Eight months later, she was found dead in her home. An autopsy showed that the amount of diphenhydramine in her blood was 500 times higher than a therapeutic concentration (from Elkhazeen et al., 2023).
What is diphenhydramine?
Diphenhydramine is a first-generation antihistamine that can be used to treat seasonal allergies, itchiness, rash, hives, insomnia, vertigo, and motion sickness. One example of a well-known diphenhydramine brand is Benadryl®.
Does Benadryl® make you sleepy?
Benadryl® can make you quite sleepy as it has a sedative effect on the body’s nervous system. If taken close to bedtime, the sleepiness can last into the next day. Benadryl® can impair your hand-eye coordination and reaction time due to sleepiness. Therefore, it is best to avoid driving while taking this medication.
Can you overdose on Benadryl®?
Yes, it is very possible to overdose on Benadryl®. The most common symptoms of Benadryl® toxicity are sleepiness, dry mouth, flushing, nausea, vomiting, and fast heartbeat. There are less frequent but more serious symptoms of diphenhydramine overdose such as confusion, hallucinations, delirium, and seizures. In some cases, Benadryl® overdose has resulted in coma or death. When taking Benadryl®, take the medication as directed and do not take more than what is recommended on the package label.
Benadryl® and alcohol—Do they mix?
Mixing alcohol and Benadryl® is a bad idea, because using these drugs in combination increases the chance of severe side effects. Sedation is the main symptom that worsens when alcohol and diphenhydramine are combined.
Benadryl® for sleep—Is it safe?
It is not safe to give Benadryl® to children for sleeping. Clinical studies have shown that Benadryl® is not effective as a treatment for sleep issues in infants and children. Furthermore, the risk of accidental overdose is high in children. Learning proper sleep hygiene and establishing a nightly routine are critical learning steps for children and should happen naturally without medicinal sleep aids.
Can I take Benadryl® while pregnant?
While studies have found that there is little added risk in pregnancy when occasionally taking Benadryl® at recommended doses, adding any new medication or dosage changes should be discussed with your physician.
Why is the Benadryl® challenge a bad idea?
The Benadryl® challenge is an unsafe practice promoted through social media that encourages people to take excessive amounts of Benadryl® to induce hallucinations. Swallowing more than the recommended amount of diphenhydramine can cause serious side effects that can result in the inability to call for emergency services. Avoid participating in social media challenges, especially those that involve taking medications. These are never safe.
What to do if someone takes too much Benadryl® or takes diphenhydramine by accident
If someone takes too much Benadryl® or takes diphenhydramine by accident, use the webPOISONCONTROL® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.
