Approach to the Patient

Bugleweed (Lycopus virginicus), has become popular as a self-treatment for hyperthyroidism. While there is some evidence bugleweed may have antithyroid effects, this is clearly not a condition in which self-treatment is advisable.

Based on weak evidence that bugleweed suppresses prolactin, it has been promoted as a treatment for cyclic mastalgia. However, there is much better evidence supporting the use of chasteberry for this condition.

Common Uses

  • Hyperthyroidism [+1]
  • Cyclic Mastalgia [+1]

(Higher numbers indicate stronger evidence; X modifier indicates contradictory results. See the Introduction for details of the rating scale.)

Hyperthyroidism +1

In vitro and animal studies suggest that bugleweed may reduce thyroid hormone levels in two ways: decreasing TSH release and impairing thyroid hormone synthesis.1–5 In addition, bugleweed may block the action of the thyroid-stimulating antibodies found in Grave’s disease.2

Cyclic Mastalgia +1

Highly preliminary evidence suggests that bugleweed may reduce prolactin secretion.4 Based on this effect, bugleweed has been suggested as a treatment for cyclic mastalgia. The same argument is used to support the use of the herb chasteberry; however, chasteberry actually has supporting evidence for efficacy in treating cyclic mastalgia.

Mechanism of Action

Not known.


The dosage of bugleweed is adjusted by measuring T4 levels; a standard starting dose is 1 to 2 g daily of the whole herb, or the equivalent dosage in extract form.

Safety Issues

The safety of bugleweed has not been established.

Long-term or high-dose use of bugleweed may cause thyroid enlargment. The herb should not be given to individuals with hypothyroidism. Sudden discontinuation of bugleweed may cause rebound hyperthyroidism.

Maximum safe dosages in individuals with severe hepatic or renal disease are not known.

Safety in Young Children and Pregnant or Lactating Women

Bugleweed should not be used by pregnant or lactating women. Maximum safe dosages for young children have not been established.

Drug Interactions

Bugleweed may interact unpredictably with thyroid replacement therapy and thyroid imaging. Due to its apparent effects on prolactin, combination treatment with bromocriptine or related agents might also result in unpredictable effects.