Fosamprenavir and Dexamethasone Ophthalmic: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fosamprenavir
Dexamethasone Ophthalmic
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 plasma concentrations of amprenavir, the active metabolite of fosamprenavir
Interaction Deep Dive
Fosamprenavir is a prodrug of amprenavir and the same interactions that occur with amprenavir are expected to occur with fosamprenavir. Concomitant use of fosamprenavir and dexamethasone may result in decreased amprenavir plasma concentrations. The mechanism of action is thought to be the induction of CYP3A4 metabolism. As a result, fosamprenavir may be less effective when used in combination with dexamethasone1.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of amprenavir, the active metabolite of fosamprenavir
Common questions
Can I take Fosamprenavir and Dexamethasone Ophthalmic together?
Decreased plasma concentrations of amprenavir, the active metabolite of fosamprenavir Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fosamprenavir and Dexamethasone Ophthalmic interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Fosamprenavir or Dexamethasone Ophthalmic 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)
- Product Information: Lexiva(R), fosamprenavir. GlaxoSmithKline, Research Triangle Park, NC, 2004. DailyMed
Keep reading about Fosamprenavir
Keep reading about Dexamethasone Ophthalmic
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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