Drug interactions
Foscarnet + Lefamulin
Severity: Major
Foscarnet and Lefamulin: 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
Lefamulin can prolong the QT interval, and foscarnet has a similar effect along with the potential to cause electrolyte disturbances. Combined use may increase the risk of ventricular arrhythmias including torsade de pointes.
What this interaction means in plain words
Foscarnet and Lefamulin 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; Lefamulin belongs to Anti Bacterial.
Why it happens
Additive QT prolongation, with foscarnet-induced electrolyte abnormalities contributing.
What to do
Prefer an alternative antibacterial if foscarnet is required. If both are used, obtain an ECG and correct electrolytes, then monitor during therapy.
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 Lefamulin
- Lefamulin + Methadone Contraindicated
- Lefamulin + Pimavanserin Contraindicated
- Lefamulin + Pimozide Contraindicated
- Lefamulin + Quinidine Contraindicated
- Alfuzosin + Lefamulin Major
- Amiodarone + Lefamulin Major
Frequently asked questions
Can I take Foscarnet with Lefamulin?
MediHelp rates the interaction as major. Foscarnet and Lefamulin 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. Lefamulin can prolong the QT interval, and foscarnet has a similar effect along with the potential to cause electrolyte disturbances. Combined use may increase the risk of ventricular arrhythmias including torsade de pointes.
How serious is the interaction between Foscarnet and Lefamulin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer an alternative antibacterial if foscarnet is required. If both are used, obtain an ECG and correct electrolytes, then monitor during therapy.
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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