Is Fiber (Psyllium Husk, Glucomannan) Safe with Liothyronine?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Take liothyronine at least 30–60 minutes before consuming fiber supplements or high-fiber foods. Avoid taking psyllium husk, glucomannan, or other soluble fiber supplements within 2 hours of your thyroid medication. Fiber supplements should be taken with meals, not near thyroid doses.
Why this interaction occurs
Soluble fiber supplements bind bile acids and can also adsorb thyroid hormones including liothyronine (T3) in the gastrointestinal lumen, reducing their absorption. This is particularly relevant for liothyronine given its faster absorption kinetics and more immediate clinical impact compared to T4. Consistent fiber supplementation near thyroid doses can lower free T3 levels and cause fatigue, cognitive symptoms, and poor thyroid control.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 8,329 reports mentioning Liothyronine. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Liothyronine + 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 Fiber (Psyllium Husk, Glucomannan) interactions → · All Liothyronine interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.