Bugleweed (Lycopus virginicus), from the mint family, is a native of North America. It is closely related to the European herb called gypsywort or gypsyweed (L. europaeus). For medicinal purposes, these two plants are often used interchangeably. The leaves of bugleweed are long and thin and grow in pairs from the stem. Small whitish flowers grow around the stem at the base of each pair of leaves.
The juice of bugleweed can be used as a fabric dye, and it was reportedly used by gypsies to darken their skin, which may be the origin of the common names applied to the European species of Lycopus.
Bugleweed also has a long-standing reputation as a medicinal plant. Herbalists have traditionally used bugleweed as a sedative, to treat mild heart conditions, and to reduce fever and mucus production in flus and colds. More recently, bugleweed has been suggested as a treatment for hyperthyroidism and mastodynia (breast pain).
Several very preliminary studies suggest that bugleweed may be helpful for treating mild hyperthyroidism.
Hyperthyroidism is a condition in which the thyroid gland releases excessive amounts of thyroid hormone. Symptoms include weight loss, weakness, heart palpitations, and anxiety. Test tube and animal studies suggest that bugleweed may reduce thyroid hormone by decreasing levels of TSH (a hormone that stimulates the thyroid gland) and by impairing thyroid hormone synthesis.1–5 In addition, bugleweed may block the action of thyroid-stimulating antibodies found in Grave's disease.6
Note: Self-treatment of hyperthyroidism can be dangerous. Physician supervision is necessary to determine why the thyroid is overactive to design a specific treatment plan.
Bugleweed may also reduce levels of the hormone prolactin, which is primarily responsible for the production of breast milk.7 Elevated levels of prolactin may also cause breast pain in women; based on this finding, bugleweed has been recommended as a treatment for cyclic mastalgia (breast tenderness that comes and goes with the menstrual cycle). However, due to its effects on thyroid hormone, we do not recommend that it be used for this purpose.
The dosage of bugleweed must be adjusted by measuring thyroid hormone levels.
The safety of bugleweed has not been established. Long-term or high-dose use of the herb may cause an enlarged thyroid. Bugleweed should not be used by individuals with hypothyroidism (low thyroid hormone) or an enlarged thyroid gland. Pregnant or nursing women should also avoid bugleweed because of potential effects on their children as well as on breast milk production.
Bugleweed should not be combined with thyroid medications. It may also interfere with diagnostic procedures that rely on radioactive isotopes to evaluate the thyroid.
If you are taking thyroid medications, do not use bugleweed.
If you are undergoing tests of your thyroid function, do not use bugleweed except on physician advice.
1. Kohrle J, Auf'mkolk M, Winterhoff H. Iodothyronine deiodinases: inhibition by plant extracts . Acta Endocrinol . 1981;96:15–16.
2. Auf'mkolk M, Ingbar JC, Kubota K, et al. Extracts and auto-oxidized constituents of certain plants inhibit the receptor-binding and the biological activity of graves' immunoglobulins. Endocrinology. 1985;116:1687–1693.
3. Auf'mkolk M, Kohrle J, Gumbinger H, et al. Antihormonal effects of plant extracts: iodothyronine deiodinase of rate liver is inhibited by extracts and secondary metabolites of plants. Horm Metab Res. 1984;16:188–192.
4. 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 Med. 1982;45:78–86.
5. Brinker F. Inhibition of endocrine function by botanical agents. I. Boraginaceae and Labiatae. J Naturopath Med. 1990;1:10–18.
6. Auf'mkolk M, Ingbar JC, Kubota K, et al. Extracts and auto-oxidized constituents of certain plants inhibit the receptor-binding and the biological activity of graves' immunoglobulins. Endocrinology. 1985;116:1687–1693.
7. 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 Med. 1982;45:78–86.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015