Lanthanum and Ampicillin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lanthanum
Ampicillin
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
Reduced ampicillin bioavailability
Interaction Deep Dive
Use caution with coadministration of ampicillin and lanthanum, as reduced ampicillin bioavailability may occur. If concurrent use is required, avoid ampicillin administration within 2 hours of lanthanum dosing1.
Why it happens (mechanism)
Binding of ampicillin to cationic groups of lanthanum
Common questions
Can I take Lanthanum and Ampicillin together?
Reduced ampicillin bioavailability Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lanthanum and Ampicillin interaction?
It is rated moderate. Can be significant — usually manageable with 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Lanthanum or Ampicillin 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 anything you'd monitor while I'm on both?
References (1)
- Product Information: FOSRENOL(R) oral chewable tablets oral powder, lanthanum carbonate oral chewable tablets oral powder. Shire US Inc. (per FDA), Wayne, IN, 2014. DailyMed
Keep reading about Lanthanum
Keep reading about Ampicillin
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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