What the FDA labels say about taking them together
Codeine and ritonavir
Codeine's FDA label of December 22, 2025 names ritonavir in its drug interactions section; ritonavir's label does not name codeine itself but warns about its class (Opioids (opioid agonists)). The codeine label: “The concomitant use of Codeine Sulfate Tablets and CYP3A4 inducers can result in lower codeine levels, greater norcodeine levels, and less metabolism via 2D6 with resultant lower morphine levels, resulting in decreased …”
Check it at the source: the codeine FDA label on DailyMed (effective December 22, 2025, Hikma Pharmaceuticals USA Inc.); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the codeine label say about ritonavir?
Codeine label, drug interactionsClinical Impact: The concomitant use of Codeine Sulfate Tablets and CYP3A4 inducers can result in lower codeine levels, greater norcodeine levels, and less metabolism via 2D6 with resultant lower morphine levels, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. … Intervention: If concomitant use of a CYP3A4 inducer is necessary, evaluate patients at frequent intervals for reduced efficacy and signs of opioid withdrawal and consider increasing the Codeine Sulfate Tablets dosage as needed. …
Codeine label, warnings and precautionsCytochrome P450 3A4 Interaction: The concomitant use of Codeine Sulfate Tablets with all cytochrome P450 3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir) or discontinuation of a cytochrome P450 3A4 inducer such as rifampin, carbamazepine, and phenytoin, may result in an increase in codeine plasma concentrations with subsequently greater metabolism by cytochrome P450 2D6, resulting in greater morphine levels, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression.
Source: FDA drug label (Codeine sulfate), Hikma Pharmaceuticals USA Inc., effective December 22, 2025 (SPL set 010905f9-3bcb-4b50-9fe8-a3ad0010f14c), via openFDA; the full label on DailyMed
What does the ritonavir label say about codeine?
Ritonavir's label does not name codeine itself; it warns about its class (Opioids (opioid agonists)):
Ritonavir label, drug interactionsAnalgesics, Opioid: tramadol, propoxyphene, methadone, fentanyl ↑ analgesics ↓ methadone ↑ fentanyl A dose decrease may be needed for these drugs when co-administered with ritonavir.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), 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
| Codeine | Ritonavir | |
|---|---|---|
| Labeled for | Pain | HIV |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.726 per tablet 30 mg tablet | $0.607 per tablet 100 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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