Drug interactions
Carbamazepine + Ritonavir
Severity: Major
Carbamazepine 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
Carbamazepine can lower ritonavir concentrations, risking reduced antiretroviral effect and resistance. Conversely, ritonavir strongly inhibits CYP3A4 and can raise carbamazepine levels to toxic range, causing dizziness, ataxia, and diplopia.
What this interaction means in plain words
Carbamazepine 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.
Carbamazepine belongs to Central Nervous System; Ritonavir belongs to Anti Virals.
Why it happens
Carbamazepine induces CYP3A4 while ritonavir potently inhibits CYP3A4, the main pathway for carbamazepine metabolism.
What to do
Avoid if possible and use a non-inducing anticonvulsant. If used together, monitor carbamazepine serum concentrations, reduce its dose as needed, and monitor HIV viral load.
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 Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir 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 Carbamazepine with Ritonavir?
MediHelp rates the interaction as major. Carbamazepine 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. Carbamazepine can lower ritonavir concentrations, risking reduced antiretroviral effect and resistance. Conversely, ritonavir strongly inhibits CYP3A4 and can raise carbamazepine levels to toxic range, causing dizziness, ataxia, and diplopia.
How serious is the interaction between Carbamazepine 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: Avoid if possible and use a non-inducing anticonvulsant. If used together, monitor carbamazepine serum concentrations, reduce its dose as needed, and monitor HIV viral load.
What other medicines interact with Carbamazepine?
MediHelp also lists interactions of Carbamazepine with, for example, Artemether / lumefantrine, Cabotegravir, Delamanid. The full list is on the Carbamazepine page.
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