What the FDA labels say about taking them together
Cefazolin and rifampin
Rifampin's FDA label of February 11, 2026 names cefazolin in its warnings section; the cefazolin labels PlainMeds reads (4) do not name rifampin.
Check it at the source: the cefazolin FDA label on DailyMed (effective May 14, 2026, Hikma Pharmaceuticals USA Inc.); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the cefazolin label say about rifampin?
Cefazolin's label (effective May 14, 2026) and its 3 other brand-application labels do not name rifampin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cefazolin), Hikma Pharmaceuticals USA Inc., effective May 14, 2026 (SPL set 1dc9de56-e259-4546-a1db-23119a8a088e), via openFDA; the full label on DailyMed
What does the rifampin label say about cefazolin?
Rifampin label, warningsPostmarketing reports suggest that concomitant administration of high doses of cefazolin and rifampin may prolong the prothrombin time, leading to severe vitamin K–dependent coagulation disorders that may be life-threatening or fatal.
Source: FDA drug label (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), 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
| Cefazolin | Rifampin | |
|---|---|---|
| Labeled for | Urinary tract infections | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.07 per vial 1 g vial | $0.679 per capsule 300 mg capsule |
| 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