Are There Any Concerns Taking Tagrisso With Dietary Supplements?

In our latest question and answer, the pharmacist discusses potential interactions between Tagrisso and dietary supplements.


I've been on Tagrisso for one year. I take several supplements. I'm interested in taking a mushroom blend. The product is by Premier Research Labs, Premier Fermented Mushroom Blend with Probiotic Fiber. Which ingredients in the product do you believe will interfere with Tagrisso? Green Tea Leaf Extract?

Asked by Sandy On Jan 09, 2023

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jan 09, 2023
Last updated Jun 03, 2023

Key points

  • Interactions between prescription medication and herbal/natural ingredients can be difficult to definitively know due to a lack of data.
  • Premier Research Labs Premier Fermented Mushroom Blend doesn't appear to contain ingredients that studies suggest would interact with Tagrisso, aside from a potentially minor one with green tea extract.
  • Several other herbal ingredients may have an interaction with Tagrisso, including St. John's Wort and grapefruit, to name a few. Always make sure your doctor knows all the medications you are taking so you can be appropriately monitored.


Thanks for reaching out! I usually like to answer these types of questions (drug - supplement interactions) by going over all the ingredients in the dietary supplement and touching on any known drug interactions they may have.

However, the dietary supplement in question here, 'Premier Research Labs Premier Fermented Mushroom Blend', contains many different ingredients, including many types of mushrooms, and this answer would be quite lengthy to deep- dive into all of them.

Below is the 'Supplement Facts' label for the product.

Premier Fermented Mushroom Blend

The product contains:

So, instead of writing about on each ingredient individually, I only looked for ones that could potentially interact with Tagrisso (osimertinib).

Out of all the ingredients in 'Premier Fermented Mushroom Blend', it seems that the only ingredient that studies suggest could have a potential interaction with Tagrisso is green tea. You can find all of the interaction details on our 'drug-herbal interaction checker'.

Basically, green tea contains caffeine, which is metabolized by the metabolizing enzyme CYP1A2. Tagrisso can affect this enzyme and may increase or decrease its effects. The prescribing information for Tagrisso states:

Avoid concomitant administration of TAGRISSO with drugs that are sensitive substrates of CYP3A, breast cancer resistance protein (BCRP), or CYP1A2 with narrow therapeutic indices, including but not limited to fentanyl, cyclosporine, quinidine, ergot alkaloids, phenytoin, carbamazepine, as osimertinib may increase or decrease plasma concentrations of these drug.
Tagrisso Prescribing Information

Now, this interaction doesn't appear overly significant. Premier Fermented Mushroom Blend contains only a little caffeine (from green tea) and I wouldn't expect a slight change in caffeine metabolism to cause any problems for you.

I imagine you're more concerned about how ingredients in Premier Fermented Mushroom Blend could alter the effectiveness of Tagrisso and it doesn't appear any of the ingredients in the supplement are known to have a clinically significant drug interaction.

I took some extra time to really look into medicinal mushrooms (since the Premier Research Labs product contains several different ones) and the studies I found don't seem to suggest the mushrooms contained in the supplement would interact with Tagrisso.

However, as it concerns 'natural' medications, I always throw out the caveat that there is often a lack of data regarding interactions, so be sure to let your doctor know about everything you are taking so you can be appropriately monitored.

What Herbals Could Tagrisso Interact With?

Even though Tagrisso isn't known to interact with anything in 'Premier Fermented Mushroom Blend', there are some potential interactions with other natural ingredients that are important to know about.

These interactions haven't been shown directly in studies, but are theoretical, based on how Tagrisso is metabolized in our system.

Tagrisso is metabolized via CYP3A and (as mentioned in the previous section) CYP1A2. It is also a substrate of several drug transporters, such as 'p-glycoprotein' and 'Breast Cancer Resistance Protein (BCRP)'. Any drug or natural medicine that affects these could potentially alter how Tagrisso is absorbed and metabolized in the body.

Based on this, the following herbals could affect blood levels of Tagrisso (I've hyperlinked all of the interaction details to the below herbals), which could alter how it works:

This list isn't intended to be all-include of every potential drug-herbal interaction with Tagrisso, but it gives you an idea of what to be cautious with. You can look up any herbal interaction with our free interaction tool.

You can always reach back out to us for specific answers.

Final Words

I wanted to thank you for reaching out! Please do so again anytime.


  • Premier Labs Fermented Mushrooms, PRL
  • TAGRISSO Prescribing Information, AccessFDA
  • Herb–drug interactions between the medicinal mushrooms Lingzhi and Yunzhi and cytotoxic anticancer drugs: a systematic review, PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

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