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Is Slow-Release Nicotinic Acid (Niacin) Safe with levothyroxine?

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levothyroxine Slow-Release Nicotinic Acid (Niacin)
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Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature

WHAT YOU NEED TO KNOW

Inform your doctor if you are taking slow-release niacin supplements, as thyroid hormone monitoring may be needed.

Why this interaction occurs

Slow-release nicotinic acid may decrease serum thyroxine-binding globulin (TBG) concentration, altering the transport of thyroid hormones without affecting free T4 in euthyroid patients.

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

Can I take Slow-Release Nicotinic Acid (Niacin) with levothyroxine?
Generally yes, with awareness that Inform your doctor if you are taking slow-release niacin supplements, as thyroid hormone monitoring may be needed.

Related interactions

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All Slow-Release Nicotinic Acid (Niacin) interactions →  ·  All levothyroxine interactions →

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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.