Related species:
Lycopus europaeus(the European related and medicinally interchangeable species).
Common names:
Bugleweed, Egyptian’s herb, Horehound, Paul’s betony, Sweet bugle, Water bugle, Water horehound, Virginian water horehound.
Part(s) used:
Aerial parts


A perennial herb growing 60-100cm in height, with a fibrous root and a smooth, straight square stem as is typical of the Lamiaceae family. It has small dense axillary whorls of white flowers and opposite oblong, or ovate lanceolate, toothed leaves with glandular dots underneath [1-3]. Lycopus virginicus (Bugleweed) is common throughout most of North America, growing in low, damp, shady areas [4]. It flowers in the summer months and is harvested just before the buds open [2]. Lycopus europaeus (Gypsy wort) is the species native to Europe and is used interchangeably with L. virginicus (Bugleweed) [5]. It may be discriminated from L. virginicus by its more acutely angled stem, narrower leaves and closely grouped flowers [1].


The name Lycopus is derived from the Greek words lykos, meaning wolf and pous, meaning foot, so called because of a resemblance of the cut leaves to a wolf’s foot [1, 6]. The names gipsyweed and Egyptian’s herb originated from a black dye extracted from L. europaeus, stated to permanently colour wool and silk, which the gipsies and people calling themselves Egyptian’s used to stain their skin darker [7].

In the 19th century, the Eclectics held bugleweed in high regard for its effectiveness in cardiovascular disorders and compared its action to digitalis [8]. It was believed to increase contraction of the heart and arteries and was therefore a valuable remedy in cardiac conditions characterised by weakness, irregularity, palpitations, dyspnea and anxiety and was highly valued in cardiac dilation and hypertrophy [8]. It was said to be antihaemorrhagic and therefore useful in small frequent passive hemorrhage, such as in epistaxis, hematemesis, hematuria, metrorrhagia, hemoptysis and intestinal bleeding [2]. It was also widely used for chronic debilitating pulmonary conditions for its anti-tussive and expectorant capabilities [8]. Herbal practitioners once considered the plant to be a mild narcotic and hypoglycaemic [2].

Major Active Constituents

Phenolic acid derivatives (caffeic, rosmarinic, chlorogenic, and ellagic acids); pimaric acid methyl ester, lithospermic acid and other organic acids [2, 6, 9]. Flavone glycosides, volatile oil, tannins, luteolin [5, 10].


  • Peripheral vasoconstrictor [5, 6, 11]; cardio tonic and cardio-active diuretic, increasing force of myocardial contraction and reducing heart rate [4]
  • Thyrostatic, thyroid-stimulating hormone (TSH) and thyroxine antagonist [4]
  • Antitussive [5, 6, 11]
  • Sedative [5, 6, 11]
  • Astringent [5, 6, 11]


A number of recent studies have sought to explain the antithyrotropic activity of Lycopus spp. A number of studies suggest lithospermic acid and other organic acids such as rosmarinic acid, chlorogenic acid, ellagic acid and luteolin-7 beta-glucosidases are the active inhibitory components responsible for such anti-thyroid activity [12, 13].

In one study, freeze-dried extracts (FDE) of L.virginicus and L.europaeus, and some of their oxidised constituents were shown to exert anti-thyrotropic activity by forming adducts with TSH, thus inhibiting its ability to bind to the TSH receptor [14]. This inhibitory interaction has also been demonstrated for the Graves’ autoantibody in vitro, which resembles TSH in its ability to bind to the thyroid plasma membrane and activate the gland, which is the proposed mechanism in the pathogenesis of Graves’ disease [14]. This study examined the effect of FDE and their constituents on the binding and biological action of Graves’-IgG and found a dose-dependent decrease in TSH-binding inhibitory activity, suggesting that the active principles present in the FDE may interact with the Graves’-IgG to inhibit its ability to bind to the TSH receptor and activate the thyroid, as they do with TSH [14]. The authors concluded that these findings provide possible rationale for the empirical use of FDE in the treatment of Graves’ disease.

Another study using Lycopus europaeus aqueous ethanolic extract demonstrated antithyrotropic and antigonadotropic activity in experimental models in vivo (both after injection and oral administration). The study observed a decrease in triiodothyronine (T3) levels, possibly resulting from reduced peripheral thyroxin (T4) deiodination, decreased T4 and TSH and LH levels [4]. In this series of experiments, testosterone levels were reduced, but prolactin remained unchanged after oral administration of bugleweed extracts [4].

In another study, acute administration of freeze dried extracts (FDE) of Lycopus virginicus and other Lamiaceae species, was given to euthyroid and hypothyroid rats. The euthyroid rat serum and pituitary TSH-levels were greatly diminished by the plant extracts. In the hypothyroid rats given Lycopus virginicus, the plant extract induced pituitary TSH repletion [15]. Findings from another study using high doses of L.europaeus extracts resulted in a decreased TSH and thyroid hormones in animals but when given to hyperthyroid patients in low doses improved cardiac symptoms without changing TSH or thyroid hormone concentrations [16]. The same authors reported thyroxine treated hyperthyroid rats co-treated with an hydroethanolic extract from L.europaeus had a positive effect of reducing body temperature, even at low doses but showed no effect on body weight or food intake and no significant changes in thyroid hormone or TSH concentrations [16]. The Lycopus extract was also shown to reduce heart rate and blood pressure, alleviate cardiac hypertrophy and significantly reduce heart tissue beta-adrenoceptor density showing almost equal efficacy to a beta-blocking agent. The authors concluded that although mode of action is unclear, organo-specific anti-T4-effects of Lycopus seem to be of practical interest in thyroid conditions [16].

Clinical Outcome Studies

A review of the current literature reveals a lack of high-quality clinical trials investigating the safety and efficacy of Lycopus [9]. However, secondary sources have reported that L. europaeus inhibited iodine metabolism and thyroid T4 output in human volunteers, and was beneficial in treating hyperthyroidism in uncontrolled trials conducted in the 1940s and 50s [4].


Lycopus virginicus is considered in European herbal medicine as having antithyroid and sedative activity [2, 4]. Traditional Western herbal medicine use therefore has focused largely on hyperthyroidism especially Graves’ disease with cardiac involvement, and thyrotoxicosis with dyspnea, and associated symptoms of tachycardia, tremor, rapid pulse and exophthalmia [4, 5, 10, 11]. Being less powerful than orthodox thyroid drugs it is therefore recommended for mild thyroid hyperfunction and associated disturbances of the autonomic nervous system, and can be used long-term [4].

As yet, there are no published reports of the clinical efficacy of L. virginicus for this indication but is empirically effective for treating patients with Graves’ disease and other forms of hyperthyroidism [17]. Due to its effect on the autonomic nervous system, other Traditional Western herbal medicine uses of L. virginicus include restlessness, insomnia, anxiety, palpitations and nervous tachycardia [2, 5]. L. virginicus is also said to decrease the production of mucus and is therefore useful in conditions of copious sputum production such as pneumonia and bronchitis, and is also useful in haemoptysis, chronic cough and irritating or wet cough [2, 5, 11].

Contra-indications and Cautions

Lycopus (Bugleweed and Gipsywort) is contraindicated in conditions of thyroid hypofunction such as hypothyroidism and myxedema, and in enlargement of the thyroid, such as goitre without functional disorder [4]. It is contraindicated in pregnancy because of its potential antigonadotropic activity, and in lactation as it potentially decreases milk production [4, 12].


Lycopus should not be administered concurrently with preparations containing thyroid hormone such as thyroxine sodium (Eutroxig, Oroxine), and may interfere with administration of thyroid diagnostic procedures that use radioactive isotopes [4, 5].

Side effects

Extended therapy of high (unspecified) doses of L. virginicus (bugleweed) preparations have been implicated in a rare case of thyroid enlargement [4]. Other side effects reported in the literature from clinical use of L. virginicus preparations include an increase in size of the thyroid (goitre not linked to thyroid malfunction), and occasionally an increase in hyperthyroid symptoms such as nervousness, tachycardia, and weight loss [4]. In addition, an increase in symptoms of thyroid overactivity has been reported as a result of sudden discontinuation of bugleweed preparations [4].


Liquid extract (1:2): 2-6ml per day or 15-40ml per week [4].
Dried herb: 3-9g per day [5].

For an infusion, pour 1 cup of boiling water over 1 teaspoon or 1-2g dried herb, and infuse for 10 to 15 minutes, which should be taken three times a day [6].


1. Felter, H.W. and J.U. Lloyd. (1898). King’s American Dispensatory. (cited 18 September 2008); Available from: <>.

2. Chevallier, A., (2000). Encyclopedia of Herbal Medicine. New York: Dorling Kindersley.

3. Duke, J.A., (2000). The Green Pharmacy Herbal Handbook: Your comprehensive reference to the best herbs for healing. Rodale.

4. Bone, K., A (2003). Clinical Guide to Blending Liquid Herbs. Missouri: Churchill Livingstone.

5. Thomsen, M., (2005). Phytotherapy Desk Reference. Michael Thomsen.

6. Hoffmann, D., (2003). Medical Herbalism: The Science and Practice of Herbal Medicine. Rochester: Healing Arts Press.

7. Grieves, M., (1980). A Modern Herbal. London: Penguin.

8. Felter, H.W., (1922). The Eclectic Materia Medica, Pharmacology and Therapeutics. (cited 18 September 2008); Available from: <>.

9. Bryan, J.k, Costa, D., Davis, M., Jancar, P., Ulbricht, C., Varghese, M., Weissner, W. (2008). Bugleweed (Lycopus virginicus, Lycopus americanus, Lycopus europaes, Lycopus lucidus). Natural Standard Database. (cited 20 August 2008); Available from: <>

10. Hoffmann, D., (1998). The Herbal Handbook: A User's Guide to Medical Herbalism. Rochester: Healing Arts Press.

11. Bartram, T., (1998). Bartram's Encyclopedia of Herbal Medicine, London: Robinson.

12. Mills, S. and K. Bone, (2000). Principles and Practice of Phytotherapy. 2000, Edinburgh: Churchill Livingstone.

13. Auf'mkolk, M., et al., Antihormonal effects of plant extracts: iodothyronine deiodinase of rat liver is inhibited by extracts and secondary metabolites of plants. Horm Metab Res, 1984. 16(4): p. 188-192. (Abstract online). Available: Pubmed/Medline. (30 March 2008).

14. Auf'mkolk, M., et al., Extracts and auto-oxidized constituents of certain plants inhibit the receptor-binding and the biological activity of Graves' immunoglobulins. Endocrinology 1985. 116(5): p. 1687-1693. (Abstract online). Available: Pubmed/Medline. (30 March 2008).

15. Sourgens, H., et al., Antihormonal effects of plant extracts. Planta Medica, 1982. 45(6): p. 78-86. (Abstract online). Available: EBSCO/Medline. (30 March 2008).

16. Vonhoff, C., Baumgartner, A., Hegger, M., Korte, B., Biller, A., and Winterhoff, H., Extract of Lycopus europaeus L. reduces cardiac signs of hyperthyroidism in rats. Journal of Life Science, 2006. 78(10): p. 1063-70. (Abstract online). Available: Pubmed/Medline. (30 March 2008).

17. Yarnell, E., K. Abascal, and C. Hooper, Clinical Botanical Medicine. 2003, Larchmont: Mary Ann Liebert. (Abstract online). Available: Pubmed/Medline. (30 March 2008).


This monograph was authored in 2008 by Natalie Grant, a student in Southern Cross University’s Bachelor of Naturopathy programme, and edited by Nena Aleschewski BNat. While the author and editor have strived to cite published information accurately, Southern Cross University will not be responsible for any inaccuracies that may have occurred.

This information is provided for educational purposes only and does not constitute medical advice. If you wish to use herbal medicine as part of your health care, seek the advice of an appropriately qualified practitioner.