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Lemon balm (Melissa officinalis) is an herb in the mint family, so named for its lemon scent. 

Like most medicinal herbs, it has anti-inflammatory, anti-microbial, and some pretty impressive antioxidant properties as well.  

But its medicinal uses go far beyond just those. 

Lemon Balm for Mood and Cognition

Lemon balm has been used traditionally for anxiety. This animal study suggests that its effects are likely due to effects upon GABA receptors. 

Lemon balm helps with calm focus and alertness without decreasing task accuracy, as this study shows, as does this one. It has been studied in restless and impulsive children, and was shown to improve concentration. 

This four month study even explored lemon balm’s effects upon mild to moderate Alzheimer’s patients. and was found to significantly improve cognition and agitation. 

Lemon Balm for Insomnia

Usually treatments effective for anxiety tend to be helpful for insomnia as well. This study showed that it is the rosmarinic acid constituent of lemon balm that affects the GABA receptors, which modulate both anxiety and also often benefit sleep. 

This study combined lemon balm with valerian in menopausal women, with impressive improvements in sleep disorder symptoms. 

Lemon Balm for Bacteria, Viruses, and Fungi

Lemon balm is well known for its ability to inhibit herpetic eruptions, and is sold as a topical treatment for the first sign of an eruption. This in vitro study shows that even for HSV-1 strains that are resistant to prescription antiviral medications, lemon balm is 96% effective. Clinically, this effect is best enjoyed at the first sign of an eruption. 

Lemon balm is not just antiviral, but several of its components are also effective against gram-positive (but not gram negative) bacteria.

Lemon balm is also effective against candida albicans. 

Lemon Balm for Digestion

Lemon balm can act as a carminative herb, soothing gas and intestinal spasms. It is one of many herbs tested in combination in this study, shown to assist with IBS symptoms. 

This animal study also shows that lemon balm may be protective against gastric ulcers. 

Lemon Balm for PMS

Perhaps due to similar anti-spasmodic effects, lemon balm has been shown to decrease premenstrual symptoms in this study of 100 high school aged girls. 

Lemon Balm for Hyperthyroidism 

Another well-known use for lemon balm is for thyroid suppression in cases of hyperthyroidism and Grave’s Disease. It has been used clinically for this purpose in combination with other thyroid suppressive herbs. This study demonstrated a possible mechanism for this: the herbs bind to the stimulating autoantibodies, preventing them from stimulating the thyroid itself. 

Lemon Balm for Cardiovascular Protection

Lemon balm has also traditionally been used to treat heart palpitations. This study shows that it is an effective anti-arrhythmic agent, as does this one. 

This study further shows that perhaps because of these effects, at low doses, lemon balm seems to be cardioprotective. 

Lemon balm also has been shown to decrease plasma triglyceride and cholesterol levels, and also lowers glucose levels. This study speculates that the mechanism for the latter involves improved metabolism in the liver and decreased glucose production in the liver.  

Side Effects and Contraindications 

Given its thyroid suppressive effects, those with hypothyroidism should use caution or avoid lemon balm, though these effects are typically at higher doses. 

Some side effects have been reported, including headache, indigestion, dizziness, and anxiety. 

Due to lack of significant research, it is not recommended for pregnant or nursing women.