What the FDA labels say about taking them together
Efavirenz and telotristat
Telotristat's FDA label of August 6, 2026 names efavirenz in its drug interactions section; the efavirenz label PlainMeds reads does not name telotristat. The telotristat label: “Concomitant use of Xermelo may decrease the efficacy of drugs that are CYP2B6 substrates by decreasing their systemic exposure.”
Check it at the source: the efavirenz FDA label on DailyMed (effective March 31, 2024, Cipla USA Inc.); the telotristat FDA label on DailyMed (effective August 6, 2026).
What does the efavirenz label say about telotristat?
Efavirenz's label (effective March 31, 2024) does not name telotristat in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Efavirenz), Cipla USA Inc., effective March 31, 2024 (SPL set 92603fa5-7a2c-4bfb-9a70-aadb4fba952c), via openFDA; the full label on DailyMed
What does the telotristat label say about efavirenz?
Telotristat label, drug interactionsConcomitant use of Xermelo may decrease the efficacy of drugs that are CYP2B6 substrates (e.g., bupropion, efavirenz) by decreasing their systemic exposure.
Source: FDA drug label (Xermelo), TerSera Therapeutics LLC, effective August 6, 2026 (SPL set a4ac9d62-887c-4c8f-b04d-a5f31cec7c86), 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
| Efavirenz | Telotristat | |
|---|---|---|
| Labeled for | HIV | Diarrhea |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.28 per tablet 600 mg tablet | n/a |
| Shortage now | No current entry | 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