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Levothyroxine and iron — GPhC CRA MCQ

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EasyDrug InteractionsLevothyroxine and ironGPhC CRA

A 38-year-old woman takes levothyroxine each morning and has been prescribed ferrous sulfate for iron deficiency. She asks whether both can be taken with breakfast. What is the most important interaction to flag?

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Correct answer: A — Ferrous sulfate can reduce levothyroxine absorption

Iron salts can bind levothyroxine in the gut and reduce absorption. The medicines should be separated by an appropriate interval and taken consistently. Thyroid function may need reassessment if administration habits change. The other options do not represent the main interaction.

Reference: BNF