Published: Jul 22, 2021

When should you avoid using CBD?

In our latest question and answer, the medical cannabis pharmacist discusses certain scenarios where you might want to avoid using CBD.

Answered by: Dr. Geoffrey Brown, PharmD


Sarah Asked

What’s one reason you should not use CBD?



I wouldn’t recommend using CBD if you’re pregnant or planning to become pregnant.


CBD should be avoided if you’re taking certain medications.


CBD should be avoided if you’re allergic to CBD or other components in the cannabis plant.


Hi Sarah and thanks for your question. This is not an exhaustive list, but these are a few scenarios where I’d recommend not to use CBD.


If you’re pregnant or planning to become pregnant.

If you’re pregnant or actively trying to conceive I’d recommend you avoid using CBD, especially using it on a regular basis. This is because multiple animal studies have shown that CBD may potentially cause fetal harm (at doses way above recommended). Even though the doses that cause fetal harm are much higher than what you’re likely to be consuming, just to be on the  safe side, I’d still recommend to avoid using it when pregnant or planning to conceive. 

If you are taking certain medications.  

Another scenario where I’d recommend not to use CBD is if you’re taking certain medications that are prone to interaction with CBD. Such medications include the antiepileptic drug clobazam, the anticoagulant drug warfarin, and the immunosuppressive drug tacrolimus. CBD interferes with the metabolism of these drugs, altering their levels in the blood which can lead to adverse effects and toxicity if levels are too high, and loss of effectiveness or treatment failure if levels are too low. While most drug interactions with CBD are rare, there can be fairly serious consequences if an interaction does occur. Here are just three scenarios where CBD caused clinically significant (potentially harmful) interactions with other medications. 

In a case report highlighting a drug interaction with CBD and warfarin, increasing the dose of CBD led to warfarin toxicity and increased risk of bleeding. 

In a study that investigated the drug interaction potential of CBD and the antiepileptic drug clobazam, CBD increased blood levels of clobazam’s active metabolite by 300%!

In another case report, a patient with a kidney transplant was taking the immunosuppressive drug tacrolimus and had their tacrolimus blood levels increase 300% after receiving CBD.

If you’re allergic to CBD or other compounds in the cannabis plant. 

The last reason I’ll state to avoid using CBD is kind of obvious, but is certainly worthy of mention. If you’re allergic to CBD you should avoid using it. Since a lot of CBD products are made from whole plant extractions of the cannabis sativa plant I’d also recommend avoiding CBD products if you’re allergic to any component of the cannabis plant itself.

Again those are just some reasons and this definitely is not an exhaustive list! Always be sure to check with your doctor or pharmacist before you start using CBD and only purchase CBD from a reputable source. Thanks again and please let me know if you have any other questions!


Epidiolex [package insert]. Carlsbad, CA: Greenwich Biosciences, Inc. 2020.

Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus (PubMed)

An interaction between warfarin and cannabidiol, a case report (PubMed)

Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus (PubMed)

Dr. Geoffrey Brown, PharmD

Dr. Geoffrey Brown is a registered medical cannabis pharmacist in New York State and the founder of CannaBuff. He graduated from the University at Buffalo with a Doctor of Pharmacy degree in 2018. He has published cannabis research that's been featured by NORML and numerous news outlets. Please feel free to reach out to him if you want to connect!