Lemon Balm

What it is

Lemon balm (Melissa officinalis) is a herb with compounds such as rosmarinic acid and citral [1]. Trials used it as capsules, tablets, standardised extracts and essential oil [2][3][4].

How it might work

Researchers propose that rosmarinic acid may act on the GABA system, which helps calm brain activity; this is a proposed mechanism, and human results have not always been consistent [2].

What the research says

A 2021 meta-analysis of randomised trials found lemon balm lowered anxiety scores more than placebo (standardised difference -0.98) and depression scores (-0.47), with high variation between trials [5]. In 80 adults with chronic stable angina, 3 g a day for 8 weeks lowered depression, anxiety, stress and sleep problem scores more than placebo [4]. In 60 adults with type 2 diabetes and depression, 700 mg a day of extract for 12 weeks lowered depression and anxiety scores more than placebo [6].

For sleep, a crossover trial of 30 adults found a branded standardised extract lowered Insomnia Severity Index scores by about 3 points versus placebo [2]. A capsule combining lemon balm with Nepeta menthoides improved insomnia scores over four weeks in 67 adults [7], and a lemon balm and valerian blend improved sleep in 100 menopausal women [8]. A blend with lemon balm, valerian, saffron and L-theanine did not improve sleep more than placebo in 64 adults [9].

In a crossover trial of 49 nursing-home residents, lemon balm essential oil did not reduce agitation more than placebo [10]. In 55 adults with benign palpitations, 14 days of 500 mg lemon balm extract twice a day reduced palpitation episodes and anxious feelings compared with placebo [11].

Doses used in studies

Standardised Phytosome extract: 400 mg a day in two-week periods [2]. Hydroalcoholic extract: 700 mg a day for 12 weeks [6]. Capsules: 3 g a day for 8 weeks [4]. Phospholipid-based extract (Relissa): 400 mg a day for 3 weeks [12]. Leaf extract: 500 mg twice a day for 14 days [11]. Lemon balm with Nepeta menthoides: 1000 mg plus 400 mg each night for 4 weeks [7]. Essential oil inhaled three times a week for a month [3].

Safety and interactions

Several trials reported no serious side effects [5][11][12]. No upper safe intake or toxic dose was reported in the studies above. In cell tests, a lemon balm extract blocked thyroid-stimulating hormone from binding its receptor [13]; no human studies of thyroid effects were found. No human studies were found on interactions with sedatives, antidepressants, blood-pressure or diabetes medicines, or on pregnancy and breastfeeding. No human liver or kidney safety data were found, although trials included people with kidney failure, diabetes and angina [3][6][4]. Anyone taking medicine, pregnant or breastfeeding should ask a doctor first.

Caveats and open questions

Most trials are small and short, and the 2021 review found high variation between trials [5]. Several trials used blends, so the effect of lemon balm alone is less clear [8][7]. The branded sleep extract trial has co-authors linked to the company that makes it [2], and a 2024 review was funded by Givaudan France Naturals [1]. Registered trials of lemon balm for sleep exist, but their results were not yet available when this page was written.