What the FDA labels say about taking them together
Rifampin and tasimelteon
Tasimelteon's FDA label of August 4, 2026 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name tasimelteon. The tasimelteon label: “DRUG INTERACTIONS Strong CYP1A2 inhibitors (e.g., fluvoxamine): Avoid use of HETLIOZ in combination with strong CYP1A2 inhibitors because of increased exposure Strong CYP3A4 inducers (e.g., rifampin):”
Check it at the source: the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.); the tasimelteon FDA label on DailyMed (effective August 4, 2026, Vanda Pharmaceuticals Inc.).
What does the rifampin label say about tasimelteon?
Rifampin's label (effective February 11, 2026) does not name tasimelteon 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
What does the tasimelteon label say about rifampin?
Tasimelteon label, drug interactionsDRUG INTERACTIONS Strong CYP1A2 inhibitors (e.g., fluvoxamine): Avoid use of HETLIOZ in combination with strong CYP1A2 inhibitors because of increased exposure ( 7.1 , 12.3 ) Strong CYP3A4 inducers (e.g., rifampin):
Source: FDA drug label (Hetlioz), Vanda Pharmaceuticals Inc., effective August 4, 2026 (SPL set ca4a9b63-708e-49e9-8f9b-010625443b90), 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
| Rifampin | Tasimelteon | |
|---|---|---|
| Labeled for | n/a | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.679 per capsule 300 mg capsule | $228.25 per capsule 20 mg capsule |
| Shortage now | In shortage | 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