What the FDA labels say about taking them together
Darunavir and methadone
Darunavir's FDA label of August 29, 2025 names methadone in its drug interactions section, and methadone's label names darunavir too. The methadone label: “The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.”
Check it at the source: the darunavir FDA label on DailyMed (effective August 29, 2025, Janssen Products LP); the methadone FDA label on DailyMed (effective December 8, 2025, Epic Pharma, LLC).
What does the darunavir label say about methadone?
Darunavir label, drug interactionsConcomitant Drug Class Drug Name Examples: methadone; Effect on Concentration of Darunavir Or Concomitant Drug: ↓ methadone; Clinical Comment: No adjustment of methadone dosage is required when initiating co-administration of PREZISTA/ritonavir. However, clinical monitoring is recommended as the dose of methadone during maintenance therapy may need to be adjusted in some patients.
Source: FDA drug label (PREZISTA), Janssen Products LP, effective August 29, 2025 (SPL set 814301f9-c990-46a5-b481-2879a521a16f), via openFDA; the full label on DailyMed
What does the methadone label say about darunavir?
Methadone label, drug interactionsClinical Impact: The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. … antiretroviral agents with CYP3A4 inhibitory activity, alone and in combination, such as abacavir, amprenavir, darunavir+ritonavir, efavirenz, nelfinavir, nevirapine, ritonavir, telaprevir, lopinavir+ ritonavir, saquinavir+ ritonavir, and tipranavir+ ritonavir, has resulted in increased clearance or …
Source: FDA drug label (Diskets, NDA017058), Hikma Pharmaceuticals USA Inc., effective December 1, 2025 (SPL set e6af84de-cbfc-4a3b-bd73-6bcf77337168), via openFDA
Source: FDA drug label (Methadose, NDA017116), SpecGx LLC, effective April 27, 2026 (SPL set 808a9d0b-720b-4034-a862-5122ff514608), via openFDA
Source: FDA drug label (Methadone Hydrochloride), Epic Pharma, LLC, effective December 8, 2025 (SPL set 6da7501b-b881-4bc7-891a-74214a00a3ac), 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
| Darunavir | Methadone | |
|---|---|---|
| Labeled for | HIV | Pain, Opioid use disorder |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.16 per tablet 600 mg tablet | $0.177 per tablet 10 mg tablet |
| 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