Lemon balm

Most single-dose trials of lemon balm in healthy adults came from one research group: DO Kennedy and AB Scholey are authors on three of them, and Scholey led a fourth [1][2][3][4]. Longer trials mostly enrolled people with symptoms or a diagnosis; each section names the population. Results in clinical groups may not apply to healthy adults. Our grades are proposals per outcome; the evidence grading method explains what each grade requires.

Does lemon balm make people feel calmer?

The evidence is mixed. Calmness here means a self-rating on the Bond-Lader mood scales, measured over hours after a single dose [1][2].

In a 2002 double-blind crossover trial, 20 healthy young adults took 300, 600 and 900 mg of a standardized extract (Pharmaton) or placebo, a week apart [1]. Calmness rose at the earliest time points after the lowest dose, while alertness fell at all time points after the highest dose [1]. In a 2003 trial of the same design with encapsulated dried leaf at 600, 1000 and 1600 mg, calmness rose at all time points after the highest dose [2]. In a 2004 crossover trial of 18 healthy volunteers given a laboratory stress task, 600 mg increased calmness and reduced alertness [3].

A later, larger trial from another group found no effect on its main measure [5]. In 106 young healthy adults with moderate stress complaints, 300 mg of the Zensera extract did not change overall calmness, the primary outcome, compared with placebo [5]. Feelings of calmness did recover after demanding test sessions with the extract, which was not seen with placebo [5]. The study was funded by the ingredient supplier Givaudan France Naturals, and two authors were employed by Givaudan [5].

The funding of the three earlier trials is not stated in their PubMed records [1][2][3]. All of this evidence is short-term and self-rated.

Does a single dose of lemon balm change thinking?

Results go in both directions, depending on dose and test [1][2]. In the 2002 trial, 600 mg improved accuracy of attention, while memory factors fell at certain doses and times [1]. In the 2003 trial, 1600 mg improved memory performance, but slower timed memory and poorer rapid visual information processing became more marked as the dose went down [2]. In the 2004 stress trial, 300 mg sped up mathematical processing with no loss of accuracy [3].

Food formats gave a similar mixed picture [4]. Two crossover studies, sponsored by Rudolf Wild GmbH & Co. KG and Cognis GmbH, which contributed to design discussions, gave lemon balm in a drink (25 participants) and a yogurt (21 participants) [4]. In the drink study, the 0.3 g dose with fruit sweetener was linked to lower state anxiety and better working memory at 1 and 3 hours, while the 0.6 g dose with artificial sweetener was linked to higher state anxiety at 3 hours [4]. The authors describe "costs" at some doses and effects that depended partly on the food used [4].

In the Givaudan-funded parallel trial of 106 stressed young adults, 300 mg improved performance on the hardest executive function trials at 5 hours [5]. That was not the primary outcome [5].

Does lemon balm affect mood over weeks?

The pooled evidence comes from people with symptoms, not from the general population [7]. A 2021 meta-analysis of randomized trials in patients with symptoms of anxiety or depression found lower anxiety scores (SMD -0.98; 95% CI -1.63 to -0.33) and depression scores (SMD -0.47; 95% CI -0.73 to -0.21) with lemon balm than with placebo [7]. SMD, a standardized mean difference, compares effects measured on different scales. The authors warned that heterogeneity between studies was high and that the number of trials was small [7].

In a 3-week trial of 100 healthy adults with moderate distress or poor sleep, 200 mg of the Relissa extract twice a day was followed by significant improvements in mood, anxiety, stress and wellbeing scores (all p values < 0.001) [8]. The extract and placebo tablets were donated by the ingredient supplier Indena S.p.A. [8].

Two trials in clinical populations also reported better scores [9][10]. In 44 people with type 2 diabetes and symptoms of depression who completed 12 weeks of 700 mg a day, depression and anxiety scores improved compared with a control [9]. In 80 people with chronic stable angina, 3 g a day for 8 weeks lowered depression, anxiety and stress scores compared with placebo [10]. Results in clinical groups may not apply to healthy adults.

Does lemon balm improve sleep quality?

Small, mostly industry-linked trials lean toward better sleep scores; one 12-week clinical trial found none [8][9][11]. In the 3-week Relissa trial (product donated by Indena), sleep scores on the Pittsburgh Sleep Quality Index improved more with the extract than with placebo, but the extract group started with significantly worse scores (p = 0.006) [8].

In a crossover trial of 30 adults who woke tired after unrefreshing sleep, 2 tablets of Melissa officinalis Phytosome (Meloff) each evening for 2 weeks lowered scores on the ISI, a sleep-difficulty questionnaire, to 6.8 ± 4.1, compared with 9.7 ± 3.7 on placebo (p = 0.003) [11]. In the same trial, 87% of participants reported better sleep on the extract, compared with 30% on placebo, and anxiety levels did not change [11]. The lead author is scientific director of Pharmextracta, which makes the product, and two authors consult for the company [11].

In the angina trial, total sleep disturbance fell with 3 g a day compared with placebo [10]. In the diabetes trial, sleep quality did not differ from the control after 12 weeks [9]. An open-label pilot of the Cyracos extract, supported by Naturex, found that clinician-rated sleep difficulty fell by 42% over 15 days in 20 stressed volunteers with mild-to-moderate anxiety and sleep disturbances [12]. Without a placebo group, it cannot separate the extract from other causes.

Does lemon balm affect overall cognition in older adults?

The largest trial found no effect on its primary outcome [13]. In 323 older adults with subjective or mild cognitive impairment who took an extract providing 500 mg of rosmarinic acid a day for 96 weeks, no cognitive measure differed from placebo [13]. In a subgroup analysis of participants without high blood pressure, scores on one clinical rating scale (CDR-SB) differed between groups (p = 0.036) [13].

A smaller, older trial in a clinical population reported a benefit [14]. In 42 people aged 65 to 80 with mild to moderate Alzheimer's disease, 60 drops a day of an extract for 4 months gave better scores on the ADAS-cog and CDR scales than placebo [14]. Results in clinical groups may not apply to healthy adults.

What the evidence does not show

The trials above do not show lasting effects of lemon balm on calmness or thinking in healthy adults: the Bond-Lader calmness and thinking trials in healthy adults tested single doses and measured effects over hours [1][2][3][5]; the one 3-week trial reported only within-group changes [8]. Evidence for combination products cannot be credited to lemon balm alone. In one crossover trial of 24 healthy volunteers, a lemon balm and valerian product lowered anxiety ratings at 600 mg, but raised them in one session at 1800 mg, and all three doses worsened Stroop task performance [6]. The European Medicines Agency based its conclusions on long-standing use and says clinical-trial evidence is insufficient but effectiveness is plausible [25].

In a pharmacokinetic study of 11 healthy individuals, serum rosmarinic acid peaked 1 hour after an extract containing 500 mg of rosmarinic acid taken fasting, with a maximum concentration of 162.20 nmol/L [15]. Food increased total exposure and delayed the peak [15]. In the single-dose calmness trials, effects were measured from 1 to 6 hours after dosing [1][2].

Forms studied include standardized extracts, encapsulated dried leaf, drinks, yogurt and tablets with a phospholipid carrier designed to improve absorption [1][2][3][4][8]. The Phytosome sleep trial gave the tablets 30 minutes before bed [11]. As of November 11, 2026 we found no trials comparing cycled with continuous use of lemon balm (PubMed search, November 11, 2026).

Trials and reviews report no serious side effects and only a few minor ones [7][22]. LiverTox says that in small trials, lemon balm extracts were linked to only a few minor, non-specific side effects (headache, dizziness, bloating), often at a similar rate to placebo [22]. LiverTox rates lemon balm with likelihood score E, an unlikely cause of clinically apparent liver injury, and found no published cases [22]. LactMed says nausea, vomiting, abdominal pain, dizziness and wheezing occur occasionally in adults [23].

The 2021 meta-analysis reported no serious side effects [7]. In the 3-week Relissa trial, no treatment-emergent or serious adverse events were reported [8]. In the pharmacokinetic study, a single dose did not affect liver, kidney or blood cell measures, and no adverse events were reported [15].

The European Medicines Agency's monograph lists undesirable effects as "None known" and says lemon balm may impair the ability to drive and use machines [24]. Health Canada requires a caution about driving or using machinery because of possible drowsiness [26]. The monograph lists hypersensitivity to the herb as a contraindication [24].

In laboratory and animal testing by researchers employed by Givaudan, which makes the extract tested, an aqueous extract was not genotoxic in cell and bacterial assays, and in a 90-day study in rats the no-observed-adverse-effect level was at least 3046.1 mg/kg body weight a day, the highest dose tested in males [16].

The European Medicines Agency's monograph says no interaction data are available [24]. As of November 11, 2026 we found no human study of interactions between lemon balm and any medicine (PubMed search, November 11, 2026). A 2016 review notes that data on interactions with standard medicines are still limited [17].

A 1985 laboratory paper reports earlier findings that freeze-dried lemon balm extract has antithyrotropic activity, meaning it binds thyroid-stimulating hormone (TSH) so that the hormone no longer binds well to its receptor [18]. This was a cell and tissue study, not a human trial, and its relevance to people taking lemon balm is unknown.

Health Canada and the European Medicines Agency also caution about driving or using machines (see Safety) [24][26]. These sources describe what has been reported, not what is right for any individual. If you take any medicines, including thyroid medicines, talk to your doctor or pharmacist before combining them with lemon balm.