Lemon balm (Melissa officinalis) is a small, bushy perennial herb in the mint family. Its small white flowers are much beloved by bees: The genus name, Melissa, is Greek for “honey bee”. The plant has a two-thousand-year history of use in food as a sweetener and flavoring agent.^[20] Lemon balm’s leaves release a strong lemon scent when crushed. The leaves are traditionally used in European herbal medicine for stress relief, for bloating and flatulence, as a sleep aid,^[21] and externally as an antiviral, particularly for cold sores.^[22] Middle Eastern traditional medicine has used the whole lemon balm plant to treat stress, insomnia, depression, anxiety, heart palpitations, paralysis, epilepsy, rheumatism (externally), cough, and fever.^[22][12][23] Lemon balm is also used as a natural food flavoring in Europe,^[21] and the FDA lists lemon balm as generally regarded as safe (GRAS) when used as a spice, as well as listing its essential oil (known as Balm Oil) as GRAS as a flavoring ingredient.^[24]

Lemon balm’s main benefits are the reduction of anxiety and depression;^[12] it can also benefit sleep, especially in the context of anxiety, depression and stress,^{[25][4][3][23][26][27]} and may help with PMS symptoms.^{[28][29][30][31]} Lemon balm can also reduce total cholesterol, especially in people with cardiometabolic conditions, and may also improve levels of other blood lipids and reduce systolic blood pressure.^[2][32] Lemon balm cream is moderately effective for oral herpes lesions (cold sores) when applied at the first sign of a sore but is probably not as effective as oral antivirals.^[10][33][34] Lemon balm has shown some promise for other skin conditions,^[35][36][37] for agitation in people with dementia,^[9][38][14] and for heart palpitations,^[23] but more research is needed. Lemon balm has also been studied for memory,^[8][7] dementia,^[9][5][6] and sleep bruxism,^[39] but the limited amount of human research does not show promise. Finally, lemon balm has traditionally been used to help digestion, but there is not much human research in this area to date.^[21][40][41]

As might be expected given its 2,000-year history of traditional use as a food, tea and medicine, lemon balm has an excellent safety track record. No serious negative effects have been associated with lemon balm to date.^[42] The flip side of lemon balm’s calming, sedative effect, however, is that it may reduce alertness.^[40][43][42]

Other things to be aware of:

• People with glaucoma should use care because of anecdotal reports that lemon balm may increase intraocular pressure.^[40][42]
• People with thyroid conditions should use care because of the theoretical possibility of lemon balm affecting thyroid hormone levels.^{[44][45][46][47][48]}
• People who take selective serotonin reuptake inhibitors (SSRIs) should be aware of the theoretical possibility that lemon balm could reduce their effectiveness.^[43][42]

Lemon balm is rich in antioxidants,^[40] some of which may help improve stress and anxiety by increasing the levels of the neurotransmitter γ-aminobutyric acid (GABA) in the brain , as well as reducing oxidative stress.^[42][25] Lemon balm’s antioxidants are likely also responsible for its positive effects on blood lipids.^[42] Some, but not all, lemon balm extracts have effects on nicotinic and muscarinic receptors in the lab.^[8][7] Although we know that these receptors play a role in forming new memories,^[49] it’s not clear whether lemon balm’s effect on them in the lab translates into cognitive effects in humans. Finally, in vitro research has found that in the lab, lemon balm extracts may keep herpes viruses from attaching to and entering cells, interfere with viral replication, keep the virus from aggregating into plaques, and directly affect the virus’s envelope. Some of these antiviral effects are attributable to lemon balm’s water-soluble polyphenols, notably rosmarinic acid, and some can be attributed to components of the essential oil, such as citral and citronellal.^[50]