Can You Take Benadryl And Zyrtec Together?

In our latest question and answer, the pharmacist discusses if it safe to take Benadryl and Zyrtec together.


I am on Zyrtec daily for allergies and my doctor said it was okay to take Benadryl at night but I thought they should not be taken together. What do you think?

Asked by Nathan On Jun 15, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Jun 15, 2018

Benadryl Title PictureYou should not take Zyrtec (cetirizine) together with Benadryl (diphenhydramine) together unless prescribed by your doctor as taking both will likely result in additive side effects, including:

  • Dry mouth
  • Drowsiness
  • Constipation
  • Dry eyes
  • Difficulty urinating
  • Blurred vision
  • Fast heartbeat

Now there may be situations where it okay to take Benadryl and Zyrtec together upon the advice from your doctor. These situations include:

  • Taking Benadryl for an allergic reaction
  • Taking Benadryl at night as a sleep aid

Taking Benadryl With Zyrtec For An Allergic Reaction

Zyrtec is typically taken on a daily basis for the prevention of allergies. However, if you are having an allergic reaction (to a bee sting for example), Benadryl may be recommended to take as most studies show that is more effective than other antihistamines in reducing swelling and hives. Therefore, if you take Zyrtec daily, your doctor may recommend to take Benadryl only as needed for allergic reactions.

Taking Benadryl With Zyrtec For Insomnia

Benadryl, as a sedating antihistamine, is a commonly used as a night time sleep aid. In fact, diphenhydramine, the active ingredient in Benadryl is included in Tylenol PM and ZzzQuil, popular over the counter products for sleep. For short term use, your doctor may recommend taking Zyrtec in the morning and Benadryl in the evening for temporary treatment of insomnia.

Additional Information

If you do end up taking Benadryl and Zyrtec during the same day, be aware of the additive side effects discussed above. While daily use of both is not recommended, intermittent use together shouldn't cause too many problems.

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

About Zyrtec (Cetirizine)

Zyrtec (cetirizine) is a "second-generation" antihistamine, indicated for the treatment and prevention of perennial allergies, seasonal allergies and hives. At indicated doses (5mg and 10mg), it generally has a higher incidence of sedation than other second-generation antihistamines, such as Allegra (fexofenadine) and Claritin (loratadine). Nevertheless, it still causes less sedation than older, first-generation antihistamines such as Benadryl. Zyrtec is taken once daily, with an onset of action around one hour.

About Benadryl (Diphenhydramine)

Benadryl (diphenhydramine) is a first generation, sedating antihistamine (H1-blocker) of the ethanolamine class. It is available in oral, topical, and parenteral product forms. Benadryl is well known to cause significant sedation in most individuals and is commonly used in night-time sleep aids. Benadryl also has potent "drying" effects in most patients, which is why is causes dry mouth, dry eyes and constipation. The onset of action of Benadryl is around 15-30 minutes after taking by mouth, with peak effects occurring 1 to 3 hours later. The duration of action is around 4 to 6 hours, with this being prolonged in the elderly and in those with liver disease.

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