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Medication · Medication

Levothyroxine

Synthetic thyroid hormone (T4) replacement — one of the most-prescribed drugs in the world.

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A medication reference built from the interaction graph. It is not prescribing information — the label and your prescriber are.

What is uncertain

Read off the same rows as above. Nothing here is added that the entry does not itself record.

  • Caution with Iodine: Alters thyroid hormone needs; coordinate with the prescriber.
  • Caution with L-Tyrosine: Tyrosine is a thyroid-hormone precursor — coordinate if on thyroid meds.
  • Caution with Ashwagandha: Ashwagandha nudges thyroid hormones up — labs can drift on replacement therapy.

Interactions

Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.

  • IodineCaution

    Alters thyroid hormone needs; coordinate with the prescriber.

  • L-TyrosineCaution

    Tyrosine is a thyroid-hormone precursor — coordinate if on thyroid meds.

  • AshwagandhaCaution

    Ashwagandha nudges thyroid hormones up — labs can drift on replacement therapy.

  • MagnesiumMind the timing

    Binds thyroid hormone in the gut — separate by 4 hours.

  • IronMind the timing

    Binds thyroid hormone — separate by 4 hours.

  • CalciumMind the timing

    Binds thyroid hormone — separate by 4 hours.

  • Psyllium HuskMind the timing

    Fiber gel binds the dose — separate by 4 hours.

  • GlucomannanMind the timing

    Viscous fiber binds medications — separate by hours.

The evidence in words

What it is

Synthetic thyroid hormone (T4) replacement — one of the most-prescribed drugs in the world.

How it works

It restores thyroid hormone; its absorption is fragile and easily blocked by minerals and fiber in the gut.

What it's used for

Hypothyroidism.

Supplement & drug interactions

Levothyroxine has 8 documented interactions mapped below and in the interactions graph. The rule is separation: take it on an empty stomach and keep calcium, iron, magnesium, and fiber (psyllium) at least 4 hours away, or absorption drops. Ashwagandha and iodine can shift thyroid needs — coordinate labs.

The rule

This is a medication reference for spotting interactions, not dosing advice. Every change to a supplement stack around a prescription belongs with the person who prescribes it.

Related reading

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Sources

This entry lists no references of its own.

Last revised . A grade is this entry's reading of the evidence, not medical advice.