The terpenes, part of the pleasant smelling volatile oil from lemon balm, are thought to produce this herb’s relaxing and gas-relieving (carminative) effects. Flavonoids, phenolic acids, and other compounds appear to be responsible for lemon balm’s anti-herpes and thyroid-regulating actions. Test tube studies have found that lemon balm blocks attachment of antibodies to the thyroid cells that cause Grave’s disease (hyperthyroidism).² The brain’s signal to the thyroid (thyroid-stimulating hormone or TSH) is also blocked from further stimulating the excessively active thyroid gland in this disease. However, clinical trials proving lemon balm’s effectiveness in treating Grave’s disease are lacking.

One small preliminary trial studying sleep quality compared the effect of a combination product containing an extract of lemon balm (Melissa officinalis) and an extract of valerian root with that of the sleeping drug triazolam (Halcion). The effectiveness of the herbal combination was similar to that of Halcion, as determined by the ability to fall asleep and the quality of sleep.³ Another trial also found that the same combination of valerian and lemon balm, taken over a two-week period, is effective in improving quality of sleep.⁴

According to double-blind research, topical use of a concentrated lemon balm extract speeds healing time of herpes simplex virus sores (cold sores) on the mouth.^{5, 6}