Do Aspirin Or Zyrtec Interact With CBD (Cannabidiol)?

In our latest question and answer, the pharmacist discusses whether or not CBD Oil interacts with aspirin or Zyrtec.

Do Aspirin Or Zyrtec Interact With CBD (Cannabidiol)?
Apr 13, 2018

Brad asked

I have started CBD oil level 2 from CWHEMP. I take Hydrocodone twice a day and I'm trying to stop taking them. I read that there shouldn't be interactions with that medicine. What about taking Aspirin and Zyrtec?? Will those interact with CBD OIL? I just want to be sure. Thank you,


CBD ASPIRINCBD (cannabidiol) is one the major constituents of cannabis. In fact, depending on the chemovar of cannabis in question, CBD can make up nearly 40% of cannabis extracts.

CBD has a wide range of medicinal effects on the body and its use is growing at a rapid pace. It has been used medicinally for:

  • Anxiety
  • Bipolar disorder
  • Muscle spasm
  • Epilepsy
  • Multiple sclerosis
  • Parkinson's disease
  • Schizophrenia

Safety Of CBD (Cannabidiol)

While there is still a considerable amount we do not know about CBD, including complete actions on the body, side effects and drug interactions, research has shown it to be relatively safe for most individuals.

Studies have used CBD doses up to 300 mg daily, for up to 6 months, safely. Some studies have even used doses exceeding 1200 mg daily, and reported them to be safe up to 4 weeks.

Toxicity studies in monkeys have shown extremely large doses of CBD (over 200 mg per kg IV and perhaps 20 times more than that for oral doses) are needed to elicit toxic/deadly effects.

CBD (Cannabidiol) Drug Interactions With Zyrtec And Aspirin

Drug interaction studies with CBD are lacking and there have been no studies evaluating the use of CBD with either Zyrtec or aspirin. Nevertheless, based on available data regarding the pharmacokinetic profile of CBD, interactions with Zyrtec or aspirin seem unlikely.

The big concern with drug interactions in this case is whether or not CBD affects metabolizing enzymes, which could in turn affect how other medications are processed in the body.

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

  • CYP 2C9
  • CYP3 A4
  • CYP 2C19

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

Aspirin may be partially metabolized by CYP2C19, but not extensively. There is a chance that CBD may prolong elimination time of aspirin, which may prolong the effects of the medication. This doesn't appear as though it is clinically significant however, at least at this time.

The metabolism of Zyrtec isn't thought to be mediated by CYP enzymes and therefore isn't thought to interact with CBD.

Whether or not CBD actually does cause metabolism inhibition is up for some debate. Most studies that show CBD inhibition of metabolizing enzymes do so only in a lab setting. Often times, when humans are evaluated in regard to CBD inhibition of metabolizing enzymes, the effects aren't significant.

However, one 2017 study did report clinically significant interactions between high doses of CBD (5mg/kg/day to 50mg/kg/day) and certain anti-epileptic drugs. However, the doses used in the study far exceed what most individuals would be taking.


  • There have been no studies evaluating potential drug interactions between CBD, aspirin and Zyrtec.
  • CBD may potentially inhibit several liver metabolizing enzymes.
  • Based on the available data for CBD, aspirin and Zyrtec, there does not appear to be any clinically significant interactions.

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