What the FDA labels say about taking them together
Cobicistat and perphenazine
Cobicistat's FDA label of February 10, 2026 names perphenazine in its drug interactions section; the perphenazine label PlainMeds reads does not name cobicistat. The cobicistat label: “A decrease in the dose of antipsychotics that are metabolized by CYP3A or CYP2D6 may be needed upon coadministration.”
Check it at the source: the cobicistat FDA label on DailyMed (effective February 10, 2026, Gilead Sciences, Inc.); the perphenazine FDA label on DailyMed (effective December 12, 2024, Rising Pharma Holdings, Inc.).
What does the cobicistat label say about perphenazine?
Cobicistat label, drug interactionsConcomitant Drug Class/Drug Name: Other antipsychotics: e.g., perphenazine risperidone thioridazine; Potential Effect ↑ = Increase, ↓ = Decrease, ↔ = No change: ↑ antipsychotic; Clinical Comment: A decrease in the dose of antipsychotics that are metabolized by CYP3A or CYP2D6 may be needed upon coadministration.
Source: FDA drug label (Tybost), Gilead Sciences, Inc., effective February 10, 2026 (SPL set 3784c35c-e87f-410c-900b-8fd6313c6010), via openFDA; the full label on DailyMed
What does the perphenazine label say about cobicistat?
Perphenazine's label (effective December 12, 2024) does not name cobicistat in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (PERPHENAZINE), Rising Pharma Holdings, Inc., effective December 12, 2024 (SPL set 0ebf4c11-1810-42f6-a8e3-071616e33d5d), 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
| Cobicistat | Perphenazine | |
|---|---|---|
| Labeled for | HIV | Schizophrenia, Nausea and vomiting |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.161 per tablet 4 mg tablet |
| Shortage now | A presentation being discontinued | 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