# Drug, herbal and food interaction review for anticancer treatment

Source: https://onco.cc/protocols/anticancer-drug-interaction-review/  
OnCo record `anticancer-drug-interaction-review` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Some everyday medicines, herbal remedies, supplements and even foods such as grapefruit can make cancer drugs stronger and more toxic or weaker and less effective. Before treatment starts, and whenever anything changes, the team should check everything you take. Tell them about every tablet, remedy, vitamin and supplement, even ones you buy yourself.

## Summary

Interactions with anticancer drugs are common and change both efficacy and toxicity. ASCO-ONS (2024) requires a medication list that includes over-the-counter medicines, herbal products and supplements, updated at every encounter and reviewed by a licensed practitioner when it changes, and pre-treatment education on interactions with prescribed drugs, integrative therapies, over-the-counter drugs and foods. It notes that patients may not mention herbal products or vitamins because they do not regard them as medicines, so staff must ask. BOPA (2025) makes the interaction check part of the pharmacist's verification at cycle 1 and for any new medicine at later cycles.

The interactions that matter most are pharmacokinetic: strong CYP3A inhibitors and inducers with oral targeted drugs (the ibrutinib label requires dose changes with inhibitors, avoidance of strong inducers, and no grapefruit or Seville oranges), and acid suppressants that cut absorption of pH-dependent kinase inhibitors (erlotinib: avoid proton pump inhibitors if possible, separate H2 blockers and antacids). St John's wort, a strong inducer, lowers levels of irinotecan's active metabolite and of imatinib. A Dutch multidisciplinary group graded 290 potential interactions: 94 clinically relevant with an advised intervention, 110 not relevant, and 86 with too little evidence; it argues for building such rules into electronic prescribing. In 202 older adults on anticancer treatment, 12% used herbs and 4% had a potentially relevant herb-drug interaction, half judged clinically relevant (red yeast rice, red coneflower, turmeric, cannabis). One widely named checker, Cancer Drug Interactions (Radboud UMC and University of Liverpool), has been closed since 2023, with an archive last updated in 2022.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: drug interaction check before chemotherapy; DDI review; drug-drug interactions with anticancer drugs; herb-drug interactions; supplement interactions with chemotherapy; grapefruit and cancer drugs; CYP3A4 interactions; proton pump inhibitors and TKIs; St John's wort and chemotherapy

## Connected records

- protocols: [Anticancer treatment prescribing and pharmacy verification before each cycle](https://onco.cc/protocols/sact-prescribing-and-pharmacy-verification/), [Consent and education before anticancer treatment](https://onco.cc/protocols/consent-and-education-before-anticancer-treatment/), [Medicines reconciliation at the start of anticancer treatment and at each move between care settings](https://onco.cc/protocols/medicines-reconciliation-in-cancer-care/), [Oral anticancer medicines at home: prescribing, teaching, adherence, storage, handling and disposal](https://onco.cc/protocols/oral-anticancer-medicines-at-home/)
- technologies: [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [St John's wort: an interaction to avoid](https://onco.cc/technologies/st-johns-wort-interaction/), [Traditional Chinese herbal medicine alongside treatment](https://onco.cc/technologies/traditional-chinese-herbal-medicine/)
- drugs: [Erlotinib](https://onco.cc/drugs/erlotinib/), [Ibrutinib](https://onco.cc/drugs/ibrutinib/), [Imatinib](https://onco.cc/drugs/imatinib/), [Irinotecan (and liposomal irinotecan)](https://onco.cc/drugs/irinotecan/)

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