Drug interactions
Foscarnet + Lithium
Severity: Major
Foscarnet and Lithium: major interaction.
Last updated
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
Lithium can cause QT prolongation and sinus node dysfunction, particularly at higher serum levels, and foscarnet adds QT and electrolyte effects. Foscarnet-related renal impairment may also raise lithium concentrations.
What this interaction means in plain words
Foscarnet and Lithium 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; Lithium belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with foscarnet nephrotoxicity potentially reducing lithium clearance.
What to do
Avoid if possible; otherwise monitor serum lithium, renal function, electrolytes and ECG and reduce the lithium dose if levels rise.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Foscarnet and Lithium, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
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 Lithium
- Lithium + Thioridazine Contraindicated
- Lithium + Vandetanib Contraindicated
- Aceclofenac + Lithium Major
- Acemetacin + Lithium Major
- Amisulpride + Lithium Major
- Amlodipine-benazepril + Lithium Major
Frequently asked questions
Can I take Foscarnet with Lithium?
MediHelp rates the interaction as major. Foscarnet and Lithium 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. Lithium can cause QT prolongation and sinus node dysfunction, particularly at higher serum levels, and foscarnet adds QT and electrolyte effects. Foscarnet-related renal impairment may also raise lithium concentrations.
How serious is the interaction between Foscarnet and Lithium?
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; otherwise monitor serum lithium, renal function, electrolytes and ECG and reduce the lithium dose if levels rise.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
