About this material
Memorial Sloan Kettering (New York) — one of the world's leading cancer centres — maintains the open About Herbs database: supplement monographs written by a staff pharmacist-botanist. It is a rare source that honestly lists documented drug interactions for each supplement — no marketing, no "it's natural so it's safe".
Here is an adaptation of its mushroom monographs plus our safety research cards. The key message of the MSKCC database: the FDA does not evaluate supplements before they reach the market, and "natural" ≠ "does not interact".
Interaction map by species
| Mushroom | Medicines | What is documented | Practical takeaway |
|---|---|---|---|
| Reishi | Anticoagulants / antiplatelets | Bleeding risk; in the lab, extracts prolong INR, PT, APTT | Doctor + INR monitoring before and after starting |
| Reishi | Immunosuppressants (post-transplant, autoimmune) | Amplifies immune response — direct antagonism of therapy | MSKCC: may be unsafe — only with a physician |
| Reishi | Drugs metabolized by CYP2E1 / CYP1A2 / CYP3A4 | In vitro, reishi polysaccharides inhibit these isoenzymes; clinical significance unknown | Caution with narrow therapeutic windows |
| Reishi | Chemotherapy acting via free radicals | Reishi raises plasma antioxidant capacity — theoretical antagonism | Discuss with the oncologist before the course, not during |
| Maitake | Warfarin | Hanselin 2010 case report: INR rose, normalization after withdrawal | Our card |
| Maitake | Hypoglycemics (insulin, oral) | Synergy — combined glucose lowering may be excessive | Glucose monitoring, physician informed |
| Chaga | (not a drug — kidneys) | Three case reports of oxalate nephropathy at gram-level daily powder doses; 14.2 g oxalates/100 g measured | Our card |
| Chaga | Warfarin, hypoglycemics | Vitamin K and hypoglycemic effects described in monographs | Same logic of caution |
| Shiitake | — | No clinical interactions recorded; safe as food | Fine if it is food, not concentrate |
| Cordyceps | Immunosuppressants | Immunostimulating profile — same class of caution | Transplant patients — strictly with a physician |
The lab trap: CA72-4
A separate story MSKCC highlights as a warning: reishi spore powder raises the tumour marker CA72-4 in blood. In an oncology patient this can look like possible progression or recurrence — and may prompt unnecessary testing or a change of therapy. If you take reishi (especially spore powder) and have tumour markers drawn — your physician must know, or the test misleads.
Three rules from MSKCC practice
- Tell your physician. The most common mistake is "it's just a supplement". Taking mushroom extracts belongs on the medication list at appointments — especially before surgery (bleeding) and in oncology.
- Do not start mid-course. Any supplement is easier to introduce before or after therapy rather than changing the background mid-cycle — otherwise it is impossible to tell where the markers shifted from.
- Extract ≠ food. Shiitake in soup and a shiitake concentrate in a capsule are different orders of dose. All the cautions above are about concentrates, not cuisine.
Where the data ends
Supplement interactions are studied even less than the supplements themselves: mostly case reports, in-vitro CYP-enzyme data and extrapolations. So the MSKCC rule is conservative: with any systemic therapy (anticoagulants, immunosuppression, chemotherapy, diabetes), the question "may I" belongs to a physician, not the internet. Our database provides the facts for that conversation: safety cards.