Taking Prozac (Fluoxetine) With ZzzQuil

In our latest question and answer, the pharmacist discusses whether or not Prozac (fluoxetine) can safely be taken with ZzzQuil.

May 15, 2018

Chuck asked

Can I take 20mg Prozac & zzzquil liquid. What if any are the possible side effects?


ZzzQuil, a night time sleep medication that contains diphenhydramine, and Prozac (fluoxetine) are generally considered safe to take together. However, there are some concerns:

  • Increased risk of side effects such as sedation, dizziness, and difficulty concentrating.
  • Increased risk of QT prolongation, a risk factor for ventricular arrhythmias. This is relatively rare however.

ZzzQuil contains diphenhydramine, which is also the active ingredient in Benadryl. Diphenhydramine is a "first-generation" antihistamine noted for its sedative effects and its relative sort duration of action when compared to "second-generation" antihistamines like Claritin.

ZzzQuil will begin working within 30 minutes after taking a dose and typically lasts 4 to 6 hours per dose.

Prozac (Fluoxetine)

Prozac is a SSRI (selective serotonin reuptake inhibitor) used for the treatment of major depressive disorder and certain anxiety conditions. SSRIs work by increasing the amount of serotonin available in the brain.

Prozac generally takes 4 to 6 weeks to notice any effects and it isn't uncommon for it to take up to 12 weeks to see maximum benefit. Prozac, and all SSRI medications, have a variety of drug interactions with over the counter medications and it is always a good idea to ask your pharmacist or doctor before taking any.

Taking ZzzQuil With Prozac

As mentioned above, the combination of ZzzQuil and Prozac is generally considered safe. There is a chance of increased sedation and dizziness, but since ZzzQuil is only taken at night, this isn't a major concern. In addition, the sedation caused by Prozac tends to go away the longer you take the medication.

There is also the concern of a QT prolongation and it is generally recommended to not take multiple medications that increase the risk. However, QT prolongation is relatively rare for both medications and generally only needs to be considered if an individuals has  other risk factors present (e.g., older age, female sex, bradycardia, hypokalemia, hypomagnesemia, heart disease, and higher drug concentrations).

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