Drug interactions
Levothyroxine + Sodium sulfate / ?magnesium sulfate / potassium chloride
Severity: Minor
Levothyroxine and Sodium sulfate / ?magnesium sulfate / potassium chloride: minor 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 sulfate-based bowel preparations containing magnesium may bind levothyroxine in the gut and reduce absorption. The effect is usually transient because bowel preparations are used briefly, but a dose may be poorly absorbed.
What this interaction means in plain words
Levothyroxine and Sodium sulfate / ?magnesium sulfate / potassium chloride have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Magnesium chelates levothyroxine in the gastrointestinal tract, and rapid transit may further reduce absorption.
What to do
Take levothyroxine at least 4 hours after each bowel preparation dose. No routine monitoring is needed after a single short course.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Levothyroxine
Frequently asked questions
Can I take Levothyroxine with Sodium sulfate / ?magnesium sulfate / potassium chloride?
MediHelp rates the interaction as minor. Levothyroxine and Sodium sulfate / ?magnesium sulfate / potassium chloride have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Oral sulfate-based bowel preparations containing magnesium may bind levothyroxine in the gut and reduce absorption. The effect is usually transient because bowel preparations are used briefly, but a dose may be poorly absorbed.
How serious is the interaction between Levothyroxine and Sodium sulfate / ?magnesium sulfate / potassium chloride?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Take levothyroxine at least 4 hours after each bowel preparation dose. No routine monitoring is needed after a single short course.
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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