Taking Benadryl With Meclizine

In our latest question and answer, the pharmacist discusses whether or not there is a drug interaction between meclizine and Benadryl.

May 23, 2018

Consuela asked

I use Dramamine Less Drowsy (meclizine) and wanted to know if Benadryl was safe with it.


Benadryl (diphenhydramine) and meclizine should not be used together. Both medications are antihistamines and the use of them together may cause CNS (central nervous system) and respiratory depression.

Meclizine is an antihistamine that is most commonly used for nausea, dizziness and vomiting that may be caused by motion sickness. It is the active ingredient in a variety of brand name products including:

  • Bonine
  • Antivert
  • Dramamine Less Drowsy

Meclizine is for most commonly used forvertigo (the sensation of spinning or dizziness) which is caused by a disease affecting the inner ear.

Due to the fact that this medication is an antihistamine, it can still affect the way in which the CNS processes information and potential side effects of the medication are sedation, drowsiness and dry mouth. Like other antihistamines, it is not advised to operate vehicles or heavy machinery due to the potential for severe accidents to occur because of the sedating nature of these medications.

The maximum daily dose of this meclizine is 50 mg/day.


Benadryl (diphenhydramine) is a "first-generation" antihistamine, commonly used to treat allergies, allergic reactions and for insomnia due to its sedating effects. The typical dose of Benadryl is 25mg to 50mg every four to six hours.

Diphenhydramine is a common ingredient in many over the counter sleep aids including ZzzQuil and Tylenol PM.

Taking Benadryl With Meclizine

When Benadryl is taken with meclizine, side effects become additive. It has been documented that taking too much of an antihistamine can cause CNS and respiratory depression. Common signs and symptoms of and respiratory depression are:

  • Slowed breathing
  • Slurred speech
  • Impaired thinking
  • Fatigue
  • Slowed heart rate

Due to the increased risk of side effects, they should generally not be taken together. However, your doctor may recommend that Benadryl be used in emergency situations only as it has more evidence in stemming an allergic reactions (e.g. from bee stings) than other antihistamines.

The duration of action of Benadryl is 4 to 6 hours while the duration of action of meclizine is around 8 to 12 hours. When it comes to taking both in the same day, they should be separated by at least 4 hours if taking Benadryl first and by as least 8 hours if taking meclizine first.

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