What's The Difference Between Benadryl And Unisom?
In our latest question and answer, the pharmacist compares Benadryl (diphenhydramine) and Unisom.
Can Benadryl be taken instead of Unisom 25 mg?
Aug 07, 2022- Most Unisom products contain the same active ingredient as Benadryl (diphenhydramine), though some Unisom formulations use a similar ingredient called doxylamine instead. Both medications cause drowsiness and similar side effects like dizziness, dry mouth, and constipation. These medications are not effective for long-term sleep use and should only be used for a few days, as long-term use has been linked to dementia risk.
Hi Tina and thanks for reaching out to us. What Is Benadryl?
Benadryl is the most common name of a drug called diphenhydramine, usually 25mg. It is a “first generation” antihistamine. It was originally used as an effective allergy medication, but was soon recommended to help with sleep as it almost always causes drowsiness. Additionally, it can cause dizziness, dry mouth, constipation, urinary retention, and next-day fatigue.
What Is Unisom?
Unisom is a bit less straightforward. There are several different formulations of Unisom available including:
- Unisom SleepGels (diphenhydramine 50mg)
- Unisom SleepTabs (doxylamine 25mg)
- Unisom SleepMinis (diphenhydramine 25mg)
- Unisom SleepMelts (diphenhydramine 25mg)
- Unisom PM Pain (diphenhydramine 50mg / acetaminophen 325mg)
Comparing Benadryl And Unisom
As you can see, most Unisom products contain the same ingredient as Benadryl, diphenhydramine. A 25mg dose of Benadryl should be interchangeable with a Unisom SleepMini. The Unisom SleepMelts are an orally dissolvable tablet, but are still the same drug and should have the exact same effect. Two Benadryl 25mg tablets would be equivalent to one Unisom SleepGel 50mg capsule.
Unisom SleepTabs contain a drug called doxylamine. Doxylamine is a drug that is extremely similar to Benadryl. Both are “first-generation” antihistamines. Like Benadryl, it also commonly causes drowsiness, dizziness, dry mouth, constipation, urinary retention, and next-day fatigue. For short term use, Benadryl or Unisom is generally considered safe to use for a few days for most adults. Just use one or the other, but definitely not both.
Benadryl And Unisom For Sleep
If you are using diphenhydramine or doxylamine to help you fall asleep, they are not an effective long-term strategy. They haven’t been shown to help with sleep quality beyond a few nights. Also, recently, long-term use has been linked to developing dementia later in life. If you find that your sleep quality isn’t the best, it might be a good time to reevaluate your sleep hygiene.
There’s a lot involved in sleep hygiene, and I will link you to a good resource if you’d like to read up on it more. From personal experience, I know that making sure that I don’t use my phone or watch any TV for an hour or so before bedtime helps. Bright lights like phones and your TV cause your brain to think that it’s daytime, so you tend to have a more difficult time falling asleep. Instead, I try to read a bit to decompress before I fall asleep. There’s always something that can be done to improve your sleep hygiene. I would encourage you to read up on it a bit and give it a try.
Final Words
Thanks again for reaching out!
References & sources
- Cumulative Use of Strong Anticholinergics and Incident Dementia — JAMA
- Over-the-Counter Agents for the Treatment of Occasional Disturbed Sleep or Transient Insomnia: A Systematic Review of Efficacy and Safety — The Primary Care Companion for CNS Disorders
- Diphenhydramine Monograph — PubChem
- Doxylamine Monograph — PubChem
- Unisom Product Information Page — Unisom
- Clinical guideline for the evaluation and management of chronic insomnia in adults — Journal of Clinical Sleep Medicine
Glossary — Terms in This Answer
- Diphenhydramine
- The active ingredient in Benadryl that blocks histamine to reduce allergy symptoms and cause drowsiness.
- Antihistamine
- A medication that blocks histamine in the body to reduce allergy symptoms and drowsiness.
- Doxylamine
- An active ingredient in some Unisom products that works similarly to diphenhydramine to cause drowsiness.
- Urinary retention
- The inability to fully empty the bladder, which can be a side effect of antihistamines.
- Acetaminophen
- A pain reliever and fever reducer found in some Unisom PM products.
- Dementia
- A serious decline in mental abilities including memory and thinking that can develop later in life.
- Sleep hygiene
- A set of healthy habits and practices that help improve sleep quality and falling asleep.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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