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?

Asked by Tina On Aug 07, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Aug 07, 2022
Last updated Apr 12, 2024

Key points

  • It should be OK to take either one, but Benadryl and Unisom should not be taken together. Depending on the Unisom formulation, they are either the same drug (diphenhydramine) or a very similar drug (doxylamine).
  • If you are routinely using diphenhydramine or doxylamine to help fall asleep, it might be time to reevaluate your “sleep hygiene”.

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!


About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at [email protected]! You can also connect with Dr. Brian Staiger on LinkedIn.

Recent Questions