Drug interactions
Foscarnet + Polymyxin b
Severity: Major
Foscarnet and Polymyxin b: 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
Parenteral polymyxin B is a well-recognized cause of nephrotoxicity and neurotoxicity. Combined with foscarnet, the risk of acute kidney injury is increased.
What this interaction means in plain words
Foscarnet and Polymyxin b 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.
Foscarnet belongs to Anti Virals; Polymyxin b belongs to Anti Bacterial.
Why it happens
Additive nephrotoxicity from tubular cell injury caused by both drugs.
What to do
Avoid the combination if possible. If both are essential, monitor creatinine, urine output and electrolytes daily and adjust doses to renal function.
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 Foscarnet
- Cidofovir + Foscarnet Contraindicated
- Foscarnet + Pimozide Contraindicated
- Foscarnet + Thioridazine Contraindicated
- Foscarnet + Vandetanib Contraindicated
- Adagrasib + Foscarnet Major
- Adefovir + Foscarnet Major
Other interactions of Polymyxin b
- Cidofovir + Polymyxin b Contraindicated
- Colistin + Polymyxin b Contraindicated
- Acyclovir + Polymyxin b Major
- Adefovir + Polymyxin b Major
- Amikacin + Polymyxin b Major
- Amphotericin b + Polymyxin b Major
Frequently asked questions
Can I take Foscarnet with Polymyxin b?
MediHelp rates the interaction as major. Foscarnet and Polymyxin b 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. Parenteral polymyxin B is a well-recognized cause of nephrotoxicity and neurotoxicity. Combined with foscarnet, the risk of acute kidney injury is increased.
How serious is the interaction between Foscarnet and Polymyxin b?
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 the combination if possible. If both are essential, monitor creatinine, urine output and electrolytes daily and adjust doses to renal function.
What other medicines interact with Foscarnet?
MediHelp also lists interactions of Foscarnet with, for example, Cidofovir, Pimozide, Thioridazine. The full list is on the Foscarnet page.
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