Drug interactions
Lanthanum carbonate + Levothyroxine
Severity: Moderate
Lanthanum carbonate and Levothyroxine: moderate 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
Lanthanum carbonate binds to levothyroxine in the gastrointestinal tract, reducing its absorption and possibly causing under-replacement. Raised TSH and hypothyroid symptoms can follow if doses are taken together.
What this interaction means in plain words
Lanthanum carbonate and Levothyroxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Lanthanum carbonate belongs to Miscellaneous; Levothyroxine belongs to Endocrine.
Why it happens
Lanthanum cations bind levothyroxine in the gut lumen, forming poorly absorbed complexes.
What to do
Take levothyroxine at least 2 hours before or after lanthanum, with a longer gap where feasible. Monitor TSH after starting or stopping lanthanum.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Levothyroxine
Other interactions of Lanthanum carbonate
Frequently asked questions
Can I take Lanthanum carbonate with Levothyroxine?
MediHelp rates the interaction as moderate. Lanthanum carbonate and Levothyroxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Lanthanum carbonate binds to levothyroxine in the gastrointestinal tract, reducing its absorption and possibly causing under-replacement. Raised TSH and hypothyroid symptoms can follow if doses are taken together.
How serious is the interaction between Lanthanum carbonate and Levothyroxine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Take levothyroxine at least 2 hours before or after lanthanum, with a longer gap where feasible. Monitor TSH after starting or stopping lanthanum.
What other medicines interact with Levothyroxine?
MediHelp also lists interactions of Levothyroxine with, for example, Cholestyramine, Sodium iodide i-131, Tiratricol. The full list is on the Levothyroxine page.
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