What the FDA labels say about taking them together
Efavirenz and macimorelin
Macimorelin's FDA label of February 18, 2026 names efavirenz in its drug interactions section; the efavirenz label PlainMeds reads does not name macimorelin. The macimorelin label: “Cytochrome P450 (CYP) 3A4 Inducers Co-administration of a strong CYP3A4 inducer with MACRILEN may reduce the plasma macimorelin concentrations and may lead to false positive test results.”
Check it at the source: the efavirenz FDA label on DailyMed (effective March 31, 2024, Cipla USA Inc.); the macimorelin FDA label on DailyMed (effective February 18, 2026, Aeterna Zentaris GmbH).
What does the efavirenz label say about macimorelin?
Efavirenz's label (effective March 31, 2024) does not name macimorelin 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 macimorelin label say about efavirenz?
Macimorelin label, drug interactionsCytochrome P450 (CYP) 3A4 Inducers Co-administration of a strong CYP3A4 inducer with MACRILEN (e.g., carbamazepine, enzalutamide, mitotane, phenytoin, rifampin, St. John's wort, bosentan, efavirenz, etravirine, modafinil, armodafinil, rufinamide) may reduce the plasma macimorelin concentrations and may lead to false positive test results.
Source: FDA drug label (Macrilen), Aeterna Zentaris GmbH, effective February 18, 2026 (SPL set aeb30f1a-4815-47ae-a2cb-b6b4e26372e1), 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 | Macimorelin | |
|---|---|---|
| Labeled for | HIV | n/a |
| 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