Diphenhydramine: Uses & Dosage

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson goes over a compound called diphenhydramine. Namely, you'll learn its more famous name, what some of its possible uses are, and some example dosage information as well.


Does the term diphenhydramine mean anything to you? What about Benadryl? The latter one probably means more to you than the first one. But they're the same thing. Benadryl is simply the famous brand name of a medication known generically as diphenhydramine. You may already have a clue then, as to what its uses are. Let's go over them in this lesson and some dosage information as well.


Diphenhydramine is an antihistamine. In other words, it works to counteract histamine. Histamine is a biochemical naturally produced by your body. While it has many other roles, it is most famously involved in causing or exacerbating the signs and symptoms of allergies. For instance: itching, a runny nose, or water eyes. Thus, diphenhydramine is used to treat the signs and symptoms of allergies.

But that's not all. Diphenhydramine can also help people fall asleep, especially if they have insomnia, difficulty in falling or staying asleep. This is why if you read a box of Benadryl really carefully, it will say the following:

  • Significant drowsiness may occur
  • Be careful when operating any vehicles or machinery when taking the medication

Diphenhydramine can also be used to treat various cold and flu signs and symptoms, motion sickness and some symptoms of Parkinson's disease. The latter is a disorder that negatively affects a person's movement and coordination.


As you can certainly appreciate, the dosage information for diphenhydramine will vary based on exactly what it's being used for. It will also vary based on other factors, such as the person's age. Always talk to your doctor prior to starting, stopping, or changing any medication for yourself or for anyone else.

Some example dosage information for diphenhydramine includes:

  • An adult dose for itching is 25 mg to 50 mg, by mouth, every 4-6 hours as needed, but no more than 300 mg in 24 hours.
  • An adult dose that can help someone fall asleep is 25 mg to 50 mg, by mouth, at bedtime.
  • An adult dose for motion sickness includes 25 mg to 50 mg, by mouth, every 6-8 hours.
  • A pediatric dose for cold symptoms includes 25 mg to 50 mg, by mouth, every 4-6 hours for children 12 years of age or older. The child should not take more than 300 mg in 24 hours.
  • A pediatric dosage for an allergic reaction includes 5 mg/kg/day divided equally into doses that are given every 6-8 hours. No more than 300 mg should be given in 24 hours. This dosage information is specific for children 1-12 years of age.

This dosage information may change at any time so always consult a doctor first!

Lesson Summary

Diphenhydramine, more famously labeled as Benadryl is an antihistamine, a drug that counteracts a biochemical produced in your body, one called histamine.

Diphenhydramine can be used to treat:

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