Taking Cheratussin AC With Prozac (fluoxetine) & Clonazepam

In our latest question and answer, we discuss the potential interaction between Cheratussin AC, Prozac (fluoxetine) & clonazepam.


I was prescribed Cheratussin AC for a bad cough. I currently take: Prozac: 5 mg Adderall: 20 mg 2x a day Lamictal: 200 mg 2x a day Clonazepam: 1 mg as needed.How will this combo affect me? Is it safe?

Asked by Morg On Nov 09, 2017

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Nov 09, 2017

There are some mild interactions with the drugs you are currently taking and Cheratussin AC, but nothing that would be considered major or a contraindication.

Cheratussin AC is a cough medication that contains two active ingredients, codeine and guaifenesin. It is typically prescribed for short periods of time to help relieve the cough and post nasal drip.

You are taking Prozac (fluoxetine), which is known to decrease the metabolizing ability of a major enzyme in our body known as CYP2D6. Codeine is relatively inactive in our bodies until it is metabolized to its active metabolite, morphine.

Taking fluoxetine with codeine will theoretically reduce the amount of codeine converting into morphine, thus reducing the effect of the drug. While this isn't considered a major drug interaction, the overall effect of Cheratussin AC may be reduced.

You are also taking clonazepam, a benzodiazepine, which can cause sedation and CNS (central nervous system) depression. Adding this to codeine can cause excess sedation and drowsiness. You certainly do not want to operate heavy machinery while taking this combination of medications.

As you are most likely taking Cheratussin AC for a short period of time, it would typically be considered OK to use it with your combination of drugs. However, it is important to be aware of the side effects such as sedation. Taking it at night, when you can stay home, is most likely the best and safest time to use the medication.

If you are concerned about potential interactions, please speak with your pharmacist or prescribing doctor.

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Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of PharmacistAnswers.com. 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! Brian.Staiger@PharmacistAnswers.com Office: 716-389-3076

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