Supplement analysis backed by scientific evidence · PT

← All supplements
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.

Evidence last reviewed: August 2026

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.

Scientific references

Where to buy

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in General health