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What the FDA labels say about taking them together

Cefaclor and leflunomide

Leflunomide's FDA label of June 4, 2025 names cefaclor in its drug interactions section; the cefaclor label PlainMeds reads does not name leflunomide. The leflunomide label: “In patients taking ARAVA, exposure of drugs which are OAT3 substrates may be increased.”

Check it at the source: the cefaclor FDA label on DailyMed (effective November 1, 2022, Azorian Pharma, LLC); the leflunomide FDA label on DailyMed (effective June 4, 2025, sanofi-aventis U.S. LLC).

What does the cefaclor label say about leflunomide?

Cefaclor's label (effective November 1, 2022) does 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 (Cefaclor), Azorian Pharma, LLC, effective November 1, 2022 (SPL set 224af904-38f3-4210-a750-e21006db4c66), via openFDA; the full label on DailyMed

What does the leflunomide label say about cefaclor?

Leflunomide label, drug interactions

In patients taking ARAVA, exposure of drugs which are OAT3 substrates (e.g., cefaclor, cimetidine, ciprofloxacin, penicillin G, ketoprofen, furosemide, methotrexate, zidovudine) may be increased.

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

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

4Cefaclor generic labelers
16Leflunomide generic labelers
CefaclorLeflunomide
Labeled forn/aRheumatoid arthritis
Boxed warningNoYes
Pharmacy cost (NADAC)$0.932 per capsule 250 mg capsule$0.324 per tablet 10 mg tablet
Shortage nowNo current entryA presentation being discontinued

Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)

What next?