What the FDA labels say about taking them together
Atazanavir and cobicistat
Cobicistat's FDA label of February 10, 2026 names atazanavir in its contraindications section; the atazanavir labels PlainMeds reads (2) do not name cobicistat. The cobicistat label: “DRUG INTERACTIONS TYBOST, in combination with atazanavir or darunavir, can alter the concentration of drugs metabolized by CYP3A or CYP2D6.”
Check it at the source: the atazanavir FDA label on DailyMed (effective August 6, 2025, Aurobindo Pharma Limited); the cobicistat FDA label on DailyMed (effective February 10, 2026, Gilead Sciences, Inc.).
What does the atazanavir label say about cobicistat?
Atazanavir's label (effective August 6, 2025) and its 1 other brand-application label do 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 (Atazanavir Sulfate), Aurobindo Pharma Limited, effective August 6, 2025 (SPL set 7fbea274-d6b5-4faa-bbf0-05fefab42114), via openFDA; the full label on DailyMed
What does the cobicistat label say about atazanavir?
Cobicistat label, contraindicationsCONTRAINDICATIONS The concomitant use of TYBOST with atazanavir or darunavir and the following drugs is contraindicated due to the potential for serious and/or life-threatening events or loss of therapeutic effect [see Drug Interactions (7.3) and Clinical Pharmacology (12.3) ].
Cobicistat label, drug interactionsDRUG INTERACTIONS TYBOST, in combination with atazanavir or darunavir, can alter the concentration of drugs metabolized by CYP3A or CYP2D6.
Cobicistat label, warnings and precautionsMonitor serum phosphorus in patients with or at risk for renal impairment. ( 5.2 ) TYBOST in combination with more than one antiretroviral that requires pharmacokinetic enhancement (i.e., two protease inhibitors or elvitegravir in combination with a protease inhibitor) is not recommended. ( 5.4 ) Use with HIV-1 protease inhibitors other than atazanavir or darunavir administered once daily is not recommended. ( 5.4 ) Coadministration with drugs or regimens containing ritonavir is not recommended.
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
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
| Atazanavir | Cobicistat | |
|---|---|---|
| Labeled for | HIV | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $2.23 per capsule 300 mg capsule | n/a |
| 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