Drug interactions
Cobicistat + Ritonavir
Severity: Major
Cobicistat and Ritonavir: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both are pharmacokinetic boosters that inhibit CYP3A4, so combining them gives no added benefit and duplicates inhibition. This increases the risk of unpredictable exposure and toxicity of coadministered antiretrovirals.
What this interaction means in plain words
Cobicistat and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Cobicistat belongs to Miscellaneous; Ritonavir belongs to Anti Virals.
Why it happens
Duplicate potent CYP3A4 (and transporter) inhibition by two pharmacokinetic boosters.
What to do
Do not combine; use only one booster within the regimen.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Cobicistat
- Alfuzosin + Cobicistat Contraindicated
- Apalutamide + Cobicistat Contraindicated
- Cobicistat + Colchicine Contraindicated
- Cobicistat + Dronedarone Contraindicated
- Cobicistat + Eletriptan Contraindicated
- Cobicistat + Eplerenone Contraindicated
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Cobicistat with Ritonavir?
MediHelp rates the interaction as major. Cobicistat and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both are pharmacokinetic boosters that inhibit CYP3A4, so combining them gives no added benefit and duplicates inhibition. This increases the risk of unpredictable exposure and toxicity of coadministered antiretrovirals.
How serious is the interaction between Cobicistat and Ritonavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not combine; use only one booster within the regimen.
What other medicines interact with Cobicistat?
MediHelp also lists interactions of Cobicistat with, for example, Alfuzosin, Apalutamide, Colchicine. The full list is on the Cobicistat page.
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