Drug interactions
Calcium acetate + Levothyroxine
Severity: Moderate
Calcium acetate 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
Oral calcium salts bind levothyroxine in the gut and reduce its absorption, which can raise TSH and cause hypothyroid symptoms. The effect is well documented with calcium supplements and phosphate binders.
What this interaction means in plain words
Calcium acetate 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.
Calcium acetate belongs to Genitourinary; Levothyroxine belongs to Endocrine.
Why it happens
Calcium forms insoluble complexes with levothyroxine in the gastrointestinal tract, reducing absorption.
What to do
Give levothyroxine at least 4 hours apart from calcium acetate. Check TSH about 6 to 8 weeks after any change in calcium therapy.
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 Calcium acetate
Frequently asked questions
Can I take Calcium acetate with Levothyroxine?
MediHelp rates the interaction as moderate. Calcium acetate 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. Oral calcium salts bind levothyroxine in the gut and reduce its absorption, which can raise TSH and cause hypothyroid symptoms. The effect is well documented with calcium supplements and phosphate binders.
How serious is the interaction between Calcium acetate 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: Give levothyroxine at least 4 hours apart from calcium acetate. Check TSH about 6 to 8 weeks after any change in calcium therapy.
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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