Supplements and Tamoxifen.
Tamoxifen, sold under the brand name Nolvadex, is a selective oestrogen receptor modulator (SERM).
Tamoxifen is a selective oestrogen receptor modulator (SERM). The class shows oestrogen agonist and antagonist effects that vary by tissue, which is what gives this group of drugs its distinctive clinical profile. Tamoxifen and raloxifene are the dominant UK agents. Tamoxifen is used in breast cancer that is positive for the oestrogen receptor. Raloxifene is used in osteoporosis after menopause. Mechanism varies by tissue. Agonist at bone, which gives the osteoporosis benefit. Antagonist at breast tissue, which gives the cancer benefit. Variable at endometrium and cardiovascular tissue, which underlies the differential VTE and endometrial cancer risk profiles. The supplement surface for tamoxifen centres on CYP2D6. Tamoxifen is a prodrug converted to endoxifen by CYP2D6. CYP2D6 inhibitors (some SSRIs particularly fluoxetine and paroxetine, certain supplements at high doses) reduce active metabolite formation. The clinical implication is real enough that oncologists generally avoid the CYP2D6 inhibiting SSRIs in tamoxifen patients. Supplements with phyto-oestrogenic activity (soya isoflavones, red clover) warrant care during active treatment.
We have not yet completed an explicit assessment of supplement interactions with Tamoxifen in the Distil database. That is different from saying nothing exists. We surface this distinction deliberately: the Distil checker tells you when we have explicitly assessed a pair and when we have not, because both are useful information. If you take Tamoxifen alongside a supplement, the checker below will surface anything already in our database, and the missing-item form at the bottom of the page routes uncatalogued pairs into our next curation pass.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
£49 until 30 June 2027 · £79 from 1 July 2027.
Something missing?
If a supplement or medication you take isn't in our autocomplete, tell us. What people flag joins the queue of what we add next.