What the FDA labels say about taking them together
Foscarnet and methotrexate
Foscarnet's FDA label of December 11, 2025 names methotrexate in its drug interactions section; the methotrexate labels PlainMeds reads (4) do not name foscarnet.
Check it at the source: the foscarnet FDA label on DailyMed (effective December 11, 2025, Clinigen Limited); the methotrexate FDA label on DailyMed (effective May 27, 2026, Accord Healthcare Inc.).
What does the foscarnet label say about methotrexate?
Foscarnet label, drug interactionsBecause of foscarnet's tendency to cause renal impairment, the use of FOSCAVIR should be avoided in combination with potentially nephrotoxic drugs such as aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate, tacrolimus and intravenous pentamidine (see above) unless the potential benefits outweigh the risks to the patient.
Source: FDA drug label (Foscavir), Clinigen Limited, effective December 11, 2025 (SPL set 90e3da4e-3b1f-428b-99ca-e4bed1c80028), via openFDA; the full label on DailyMed
What does the methotrexate label say about foscarnet?
Methotrexate's label (effective May 27, 2026) and its 3 other brand-application labels do not name foscarnet in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Methotrexate), Accord Healthcare Inc., effective May 27, 2026 (SPL set 874c7f43-a3be-4236-89cc-24c44e3c5813), 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
| Foscarnet | Methotrexate | |
|---|---|---|
| Labeled for | n/a | Rheumatoid arthritis, Psoriasis, Leukemia, lymphoma and myeloma, Breast cancer |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | n/a | $0.158 per tablet 2.5 mg tablet |
| Shortage now | No current entry | In shortage |
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