Does CBD Interact With NyQuil?

In our latest question and answer, the pharmacist discusses whether or not CBD (cannabidiol) oil interacts with NyQuil.

Mar 02, 2018

Owen asked

Can you take CBD oil and NyQuil together?


There is no known interaction between cannabidiol (CBD) and NyQuil. They are generally considered to be safe to take together.

However, there are very few studies evaluating potential drug interactions between CBD and other medication. Nevertheless, in studies that have been done, there has been no indication that CBD interacts with any of the ingredients contained in NyQuil.

Cannabidiol (CBD) - NyQuil Interaction Information


NyQuil is a combination ingredient medication containing:

  • Acetaminophen (analgesic)
  • Dextromethorphan (cough suppressant)
  • Doxylamine (sedating antihistamine)

NyQuil is most commonly used to treat the symptoms of cold and the flu while also providing a mild sedative effect due to the sedating antihistamine (doxylamine) contained in the product.


Cannabidiol, also known as CBD, is a major component of cannabis (i.e. marijuana). While THC (delta-9-tetrahydrocannabinol) is likely more well-known due to its psychoactive effects, CBD makes up almost 40% of cannabis extracts and has a wide range of effects and potential benefits when used medicinally.

Due to the relative recent nature of CBD use for medicinal purposes (at least legally), there is a distinct lack of studies when it comes to potential drug interactions between CBD and other medication.

Most recent studies do indicate that CBD potentially affects many different metabolizing enzymes in the body.  In fact, studies have shown that CBD can inhibit the following liver metabolizing enzymes:

  • CYP 2C9
  • CYP 3A4
  • CYP 2C19

Metabolizing enzyme inhibition often leads to increased concentrations of drugs that are typical substrates for a particular enzyme.

Most studies that show CBD inhibition of metabolizing enzymes do so only in a lab setting (i.e. in vitro). Often times when humans are evaluated in regard to CBD inhibition of metabolizing enzymes, the effects aren't significant.

In fact, many echo the following sentiment of the authors of a recent study:

"In extensive clinical application including complex drug regimens with opioids, tricyclic antidepressants, anticonvulsants, etc., no drug-drug interactions have been observed that would contraindicate or preclude use of [THC/CBD containing products] with any specific pharmaceutical, although additive sedative effects are always possible..."

As more studies are completed, we will get a better understanding of potential clinically significant interactions with CBD. One recent 2017 study reported several drug-drug interactions with CBD that involved certain anti-epileptic medications including Onfi & Topamax. It still isn't known however, how significant these interactions are.

As mentioned above, there are no such studies that looked at CBD and potential interactions with any of the ingredients in NyQuil.

Additive Sedation

One possible area of concern in using CBD with NyQuil is an increased feeling of sedation when using both together. NyQuil is used partly for its sedative effects and many studies indicate that CBD can cause mild hypnotic or sedative effects. However, as NyQuil is generally only taken at night time, the additive sedation doesn't appear to be much cause for concern.

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