Atovaquone and Ritonavir: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ritonavir
Atovaquone
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased atovaquone serum concentrations
Interaction Deep Dive
Coadministration of atovaquone and lopinavir/ritonavir and atazanavir/ritonavir has resulted in decreased serum concentrations of atovaquone1. Monitor patients for loss of atovaquone efficacy. Doses of atovaquone may need to be increased.
Why it happens (mechanism)
Increased atovaquone metabolism
Literature reports
1 report — tap to read
a) Atovaquone AUC and Cmax were decreased in HIV-infected individuals by 74% and 44% with lopinavir/ritonavir, and by 46% and 49% with atazanavir/ritonavir compared with healthy subjects not receiving antiretrovirals following a single oral dose of atovaquone 250 mg/proguanil 100 mg in a prospective study (N=76) 1.
Common questions
Can I take Atovaquone and Ritonavir together?
Decreased atovaquone serum concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atovaquone and Ritonavir interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Atovaquone or Ritonavir need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- van Luin M, Van der Ende ME, Richter C, et al: Lower atovaquone/proguanil concentrations in patients taking efavirenz, lopinavir/ritonavir or atazanavir/ritonavir. AIDS 2010; 24(8):1223-1226. PubMed
Keep reading about Ritonavir
Keep reading about Atovaquone
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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