Drug Interaction Report

Lithospermum and Liothyronine: Interaction Details

A pharmacist-reviewed analysis of the Lithospermum and Liothyronine interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Liothyronine

Cytomel Cytomel® Liomny
+

Lithospermum

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 5 documented Lithospermum interactions, 2 are rated moderate — including this one.
Onset
rapid
Evidence
theoretical
Severity
Moderate

What happens

Reduced effectiveness of thyroid hormones

Interaction Deep Dive

Animal data suggests that Lithospermum may significantly lower T4 and T3 levels12. Theoretically, this may decrease the effect of thyroid hormones. The antithyrotropic activity of Lithospermum may be due to lithospermic acid, rosmarinic acid, and/or other not yet identified constituents 67. The mechanism of antithyroid activity may be due to a combination of activities. The iodide pump mechanism of the thyroid is depressed by Lithospermum freeze-dried extract (FDE) 5. Lithospermum FDE administration decreased colloid droplets within the thyroid follicles consistent with a strong antisecretory action 4. Lithospermum inhibited the activity of thyrotropic hormone after its release from the anterior pituitary lobe 8. Peripheral T4-deiodination was inhibited by Lithospermum FDE and its phenolic components 319. Until the clinical significance of this potential interaction has been determined, it is advised that patients avoid concomitant use of Lithospermum and thyroid hormones.

Why it happens (mechanism)

Inhibition of the iodide pump mechanism of the thyroid; antisecretory activity; inhibition of thyroptropic hormone activity; inhibition of peripheral T4 deiodination

Literature reports

5 reports — tap to read

a) In thyroidectomized rats given T4, Lithospermum officinale freeze-dried extract (FDE) 20 milligrams (mg) given intravenously significantly reduced T3 levels after 6 hours compared to control (p less than 0.05), but was not as great as propylthiouracil 12 mg given subcutaneously (p less than 0.01) 1.

b) Lithospermum officinale FDE (40 milligrams (mg)/100 grams body weight) administered intravenously to hypothyroid rats suppressed circulating TSH without any effect on the hypophyseal TSH-stores. Correspondingly, goiter weight also decreased. In diluent-treated rats, T4 was 5.9 +/- 0.3 micrograms/deciliter (mcg/dL) and T3 was 89 +/- 9 mcg/dL. In Lithospermum officinale-treated rats, T4 was 4 +/- 0.3 mcg/dL (p between 0.001 and 0.005) and T3 was 43 +/- 25 mcg/dL (p between 0.001 and 0.005) 2.

c) Lithospermum ether extract fraction produced much stronger inhibition of the enzymes responsible for converting thyroxine to active forms of T3 than did the freeze-dried extract (FDE). Inhibition by lithospermum and its phenolic components of T4-deiodination enzymes iodothyronine-5'-deiodinase and T4-5-deiodinase was studied in vitro using rat liver microsomes. Of the phenolic acids tested, rosmarinic acid and ellagic acid were active while caffeic acid, ferulic acid, and chlorogenic acid were not. Based on the amounts required to produce 50% inhibition of the enzyme T4-5-deiodinase, the hot aqueous extracts (10 micrograms (mcg)) were more potent than the cold ones (20 mcg), and ether extract fractions of hot aqueous extracts (less than 0.6 mcg) were the most potent. The deiodinase inhibition by lithospermum FDE is dose dependent 3.

d) Lithospermum officinale freeze-dried extract (FDE) administered to iodine-deficient goitrous rats reduced thyroid weight and TSH levels as compared with saline injected control groups. Thyroid hormone levels were significantly lower 3 hours after coadministration of thyroid releasing hormone and Lithospermum officinale FDE, although specific values were not provided. Four days of administration of Lithospermum officinale FDE also resulted in a significantly lower peripheral thyroid hormone levels 4.

e) When Lithospermum officinale freeze-dried extract (FDE) was injected with thyroid stimulating hormone, the depressive effect on the iodide pump was enhanced compared with saline controls. However, the organification process inhibited by antithyroid drugs propylthiouracil and mercaptoimidazole was not inhibited by Lithospermum FDE. The secretory activity of the thyroid gland is suspended 24 hours after a single injection of the FDE 5.

Common questions

Can I take Lithospermum and Liothyronine together?

Reduced effectiveness of thyroid hormones Always confirm with your pharmacist or prescriber before making any change.

How serious is the Lithospermum and Liothyronine interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

How quickly could this interaction happen?

The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Lithospermum or Liothyronine need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there anything you'd monitor while I'm on both?

References (9)

  1. Winterhoff H, Sourgens H, & Kemper FH: Pharmacodynamic effects of Lithospermum officinale on the thyroid gland of rats; comparison with the effects of iodide. Horm Metabol Res 1983; 15(10):503-507.
  2. Sourgens H, Winterhoff H, Gumbinger HG, et al: Antihormonal effects of plant extracts. TSH- and prolactin-suppressing properties of Lithospermum officinale and other plants. Planta Medica 1982; 45(2):78-86. DOI
  3. Auf'mkolk M, Kohrle J, Gumbinger H, et al: Antihormonal effects of plant extracts: iodothyronine deiodinase of rat liver is inhibited by extracts and secondary metabolites of plants. Horm Metabol Res 1984; 16(4):188-192. PubMed
  4. Sourgens H, Winterhoff H, Gumbinger HG, et al: Antihormonal effects of plant extracts on hypophyseal hormones in the rat. Acta Endocrinol 1980; 234(suppl):49. DOI
  5. Sourgens H: Further investigations on the mechanism of action of freeze dried extracts of Lithospermum officinale L. (abstract). Naun Schmied Arch Pharmacol 1979; 307(suppl):201.
  6. Winterhoff H, Gumbinger HG, & Sourgens H: On the antigonadotropic activity of Lithospermum and Lycopus species and some of their phenolic constituents. Planta Medica 1988; 54(2):101-106.
  7. Wagner VH, Horhammer L, & Frank U: Lithospermic acid, the antihormonally active principle of Lycopus europaes L. and Symphytum officinale L. Arzneimittelforschung 1970; 20(5):705-712.
  8. Kemper F: Experimental basis for the therapeutic use of Lithospermum officinale for blocking of anterior pituitary hormone. Arzneim Forsch 1959; 4:411-419.
  9. Kohrle J, Auf'mkolk M, Winterhoff H, et al: Iodothyronine deiodinases: inhibition by plant extracts. Acta Endocrinol 1981; Suppl 240:15-16.
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

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