Benadryl: Side Effects, Interactions, and Overdose

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, get guidance from Poison Control immediately. Help from Poison Control can be obtained online at www.poison.org or by phone at 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.

Damon Alvarez, BA, BSPS
Fourth-Year Student Pharmacist, Doctor of Pharmacy Class of 2023