What the FDA labels say about taking them together
Liothyronine and rifampin
Liothyronine's FDA label of June 4, 2026 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name liothyronine. The liothyronine label: “Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine.”
Check it at the source: the liothyronine FDA label on DailyMed (effective June 4, 2026, Mylan Pharmaceuticals Inc.); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the liothyronine label say about rifampin?
Liothyronine label, drug interactionsDrug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine.
Source: FDA drug label (Liothyronine Sodium), NDA010379 (King Pharms), as published by Mylan Pharmaceuticals Inc., effective June 4, 2026 (SPL set 115a84c2-0126-4dd7-816e-1873875f1e49), via openFDA; the full label on DailyMed
What does the rifampin label say about liothyronine?
Rifampin's label (effective February 11, 2026) does not name liothyronine in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Liothyronine | Rifampin | |
|---|---|---|
| Labeled for | Hypothyroidism | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.294 per tablet 25 mcg tablet | $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