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Limited evidenceGeneral health

Bugleweed

A mint-family herb used in Germany for mild overactive thyroid symptoms. Two small controlled studies suggest a real but slight effect on thyroid markers, and this is not something to self-treat.

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What the science says

  • Mild hyperthyroid symptoms Limited evidence

    A controlled clinical study of Lycopus europaeus extract in patients with mild hyperthyroid symptoms reported increased urinary thyroxine excretion and modest symptom improvement, with only small changes in serum thyroid hormones. A later multicentre controlled study of a proprietary extract reported symptom improvement over several weeks.

  • Mechanism is established, magnitude is not Limited evidence

    Older laboratory work showed that oxidised extracts of Lycopus and related plants inhibit TSH binding and the activity of Graves' immunoglobulins at the thyroid receptor. The mechanism is credible, but the human trials are small, largely open or unblinded, and manufacturer-linked.

Dosage & safety

Studied doseThe German studies used standardised extracts equivalent to roughly 20–40 mg/day of the dried herb equivalent, or 1–2 g/day of dried herb as a tea, taken over four to twelve weeks.
SafetyThis herb lowers thyroid signalling and must not be used casually. Avoid entirely in hypothyroidism, in thyroid enlargement without hyperfunction, and alongside thyroid hormone replacement. It can interfere with thyroid scintigraphy, and abrupt discontinuation after prolonged use has been associated with rebound. Not for use in pregnancy or breastfeeding, as it may lower prolactin. Hyperthyroidism is a medical diagnosis that requires proper management.

How to take it

TimingTaken daily over four to twelve weeks in the German studies; no time of day is better.
With food?Either way.
Worth knowingDo not stop abruptly after prolonged use — rebound has been reported — and never self-treat suspected hyperthyroidism, which needs blood tests and a diagnosis first.

Interactions

With medications

  • levothyroxine and other thyroid hormone replacement

    Bugleweed lowers thyroid signalling and directly opposes replacement therapy. do not combine

  • antithyroid drugs (methimazole, carbimazole, propylthiouracil)

    Additive suppression that can overshoot into hypothyroidism. do not combine without medical supervision and thyroid function monitoring

  • radioiodine and thyroid scintigraphy

    It interferes with iodine uptake and can distort the scan or treatment. tell the department you take it and stop well before any thyroid imaging or radioiodine

With other supplements

  • iodine, kelp and bladderwrack

    Directly opposing actions on thyroid hormone production, making the effect of either unpredictable. do not combine

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does bugleweed work for an overactive thyroid?

Two small controlled German studies suggest bugleweed has a real but slight effect on thyroid markers and mild hyperthyroid symptoms; the trials were largely unblinded and manufacturer-linked, so the evidence is limited. Hyperthyroidism needs a diagnosis and proper management, not self-treatment.

Can you take bugleweed with levothyroxine?

No. Bugleweed lowers thyroid signalling and directly opposes thyroid hormone replacement, so do not combine them, and avoid it entirely if you have hypothyroidism.

How much bugleweed per day?

The German studies used standardised bugleweed extracts equivalent to roughly 20–40 mg/day of dried herb, or 1–2 g/day of dried herb as a tea, over four to twelve weeks. Do not stop abruptly after prolonged use, because rebound has been reported.

Is bugleweed safe while breastfeeding?

No, bugleweed is not for use in pregnancy or breastfeeding, as it may lower prolactin. Tell imaging staff if you take it, since it interferes with thyroid scintigraphy and radioiodine.

Scientific references

Related in General health

Herbal medicines: what the evidence says (335)