Nyquil Vs. ZzzQuil: What Is The Difference?

In our latest question and answer, we discuss the difference between Nyquil & ZzzQuil.


Which is better for sleeping - ZzzQuil or plain Nyquil?

Asked by Mindy On Dec 04, 2017

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Dec 04, 2017

Both Nyquil & ZzzQuil contain sedating antihistamines. ZzzQuil contains diphenhydramine, the active ingredient in Benadryl, while Nyquil contains doxylamine. Both antihistamines cause sedation shortly after administration and help you to fall asleep. 

The difference in the two products are the additional ingredients Nyquil contains for the treatment of cough/cold symptoms.

ZzzQuil contains diphenhydramine as the only ingredient.  It is intended solely for the use as a night time sleep aid.

NyQuil on the other hand, contains additional ingredients:

  • Acetaminophen (active ingredient in Tyenol) for treating fever/pain.
  • Dextromethorphan for suppressing cough.
  • Doxylamine as mentioned above, for sedation. Sedating antihistamines may also help relieve a runny nose as well as cough due to post nasal drip.

If you are only in need of something to assist in falling asleep, it's better to just stick with ZzzQuil. It will most likely do the job, without the extra ingredients and side effects you may experience from the additional ingredients contained in Nyquil.

In regard to comparing doxylamine and diphenhydramine, comparative studies and evaluations are limited and it is difficult to say one is better than the other. They are both first generation antihistamines, have a similar half life (~9-10 hours) and both reach peak concentrations in 1-3 hours.  Individuals will vary in regard to which ingredient works best for them.

About the Pharmacist

Dr. Ying Huffman

Dr. Ying Huffman is licensed pharmacist and a 2007 graduate of the University of South Carolina. She has over 10 years of experience in community and retail pharmacy. Her inquisitive nature welcomes all questions!

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