What the FDA labels say about taking them together
Leflunomide and levonorgestrel
Leflunomide's FDA label of June 4, 2025 names levonorgestrel in its drug interactions section; the levonorgestrel labels PlainMeds reads (4) do not name leflunomide. The leflunomide label: “Drugs metabolized by CYP2C8 and OAT3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs. Teriflunomide may increase exposure of ethinylestradiol and levonorgestrel.”
Check it at the source: the leflunomide FDA label on DailyMed (effective June 4, 2025, sanofi-aventis U.S. LLC); the levonorgestrel FDA label on DailyMed (effective January 31, 2023, Foundation Consumer Healthcare LLC).
What does the leflunomide label say about levonorgestrel?
Leflunomide label, drug interactionsDrugs metabolized by CYP2C8 and OAT3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs. ( 7 ) Teriflunomide may increase exposure of ethinylestradiol and levonorgestrel.
Source: FDA drug label (Arava), sanofi-aventis U.S. LLC, effective June 4, 2025 (SPL set 320f63f2-fac3-4aee-aff8-85724e00ef52), via openFDA; the full label on DailyMed
What does the levonorgestrel label say about leflunomide?
Levonorgestrel's label (effective January 31, 2023) and its 3 other brand-application labels do not name leflunomide in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Plan B One-Step), Foundation Consumer Healthcare LLC, effective January 31, 2023 (SPL set 6ce6b40e-14ac-47bd-a648-ddf9e452e559), 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
| Leflunomide | Levonorgestrel | |
|---|---|---|
| Labeled for | Rheumatoid arthritis | Birth control |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.324 per tablet 10 mg tablet | $6.33 per tablet 1.5 mg tablet |
| Shortage now | A presentation being discontinued | 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