What the FDA labels say about taking them together
Fluoroestradiol f 18 and tamoxifen
Fluoroestradiol f 18's FDA label of January 12, 2026 names tamoxifen in its drug interactions section; the tamoxifen labels PlainMeds reads (2) do not name fluoroestradiol f 18. The fluoroestradiol f 18 label: “Before administering CERIANNA, discontinue drugs that bind to the ER, such as SERMs and SERDs, for at least 5 biological half-lives.”
Check it at the source: the fluoroestradiol f 18 FDA label on DailyMed (effective January 12, 2026, GE Healthcare Inc.); the tamoxifen FDA label on DailyMed (effective December 18, 2025, Actavis Pharma, Inc.).
What does the fluoroestradiol f 18 label say about tamoxifen?
Fluoroestradiol f 18 label, drug interactionsBefore administering CERIANNA, discontinue drugs that bind to the ER, such as SERMs and SERDs, for at least 5 biological half-lives (e.g., elacestrant for 11 days, tamoxifen for 8 weeks, and fulvestrant for 28 weeks) [see Dosage and Administration (2.3) ].
Source: FDA drug label (CERIANNA), GE Healthcare Inc., effective January 12, 2026 (SPL set b2c2a2df-cf3e-4a29-a033-231ed5a94b58), via openFDA; the full label on DailyMed
What does the tamoxifen label say about fluoroestradiol f 18?
Tamoxifen's label (effective December 18, 2025) and its 1 other brand-application label do not name fluoroestradiol f 18 in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Tamoxifen Citrate), Actavis Pharma, Inc., effective December 18, 2025 (SPL set 9b8a4211-120f-4981-ad69-928accb97637), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Fluoroestradiol f 18 | Tamoxifen | |
|---|---|---|
| Labeled for | n/a | Breast cancer |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.277 per tablet 20 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once