Is Soybean / Soy Flour Safe with levothyroxine?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Avoid consuming soybean flour around the time of levothyroxine dosing; dosage adjustments may be necessary.
Why this interaction occurs
Soybean flour may bind levothyroxine in the gastrointestinal tract, decreasing its absorption and potentially reducing therapeutic efficacy.
Evidence
Evidence level: strong.
Data source
FDA Drug Label
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 302,514 reports mentioning levothyroxine. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the levothyroxine + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Soybean / Soy Flour interactions → · All levothyroxine interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.