Lemon balm has antiviral properties. A cream containing an extract of lemon balm has been shown in double-blind trials to speed the healing of cold sores.⁶ In one double-blind trial, topical application of a 1% 70:1 extract of lemon-balm leaf cream, four times daily for five days, led to significantly fewer symptoms and fewer blisters than experienced by those using a placebo cream.⁷ In most studies, the lemon-balm cream was applied two to four times per day for five to ten days.

Herbs that directly attack microbes include the following: chaparral, eucalyptus, garlic, green tea, lemon balm (antiviral), lomatium, myrrh, olive leaf, onion, oregano, pau d’arco (antifungal), rosemary, sage, sandalwood, St. John’s wort, tea tree oil, thyme, and usnea.

Lemon balm has antiviral properties. A cream containing an extract of lemon balm has been shown in double-blind trials to speed the healing of cold sores.⁸ In one double-blind trial, topical application of a 1% 70:1 extract of lemon-balm leaf cream, four times daily for five days, led to significantly fewer symptoms and fewer blisters than experienced by those using a placebo cream.⁹ In most studies, the lemon-balm cream was applied two to four times per day for five to ten days.

Carminatives are a class of herbs commonly used for infants with colic. These herbs tend to relax intestinal spasms.

Chamomile is a carminative with long history of use as a calming herb and may be used to ease intestinal cramping in colicky infants. A soothing tea made from chamomile, vervain, licorice, fennel, and lemon balm has been shown to relieve colic more effectively than placebo.¹⁰ In this study, approximately 1/2 cup (150 ml) of tea was given during each colic episode up to a maximum of three times per day.

In a double-blind trial, supplementation with an extract of lemon balm (Melissa officinalis) for 16 weeks significantly improved cognitive function and significantly reduced agitation, compared with a placebo, in people with Alzheimer's disease.¹¹ The amount of lemon balm used was 60 drops per day of a 1:1 tincture, standardized to contain at least 500 mcg per ml of citral.

A combination of valerian and lemon balm has been tested for improving sleep. A small preliminary trial compared the effect of valerian root extract (320 mg at bedtime) and an extract of lemon balm (Melissa officinalis) with that of the sleeping drug triazolam (Halcion).¹² The effectiveness of the herbal combination was similar to that of Halcion, but only the Halcion group felt hung over and had trouble concentrating the next day. A double-blind trial found that a combination of valerian and lemon balm, taken over a two-week period, was effective in improving quality of sleep.¹³

Another double-blind trial found a combination of 360 mg valerian and 240 mg lemon balm taken before bed improved reported sleep quality in one-third of the participants.¹⁴

Carminatives (also called aromatic digestive tonics or aromatic bitters) may be used to relieve symptoms of indigestion, particularly when there is excessive gas. It is believed that carminative agents work, at least in part, by relieving spasms in the intestinal tract.¹⁵

Lemon balm is a carminative herb used traditionally for indigestion.¹⁶ Lemon balm, usually taken as tea, is prepared by steeping 2–3 teaspoons of leaves in hot water for 10 to 15 minutes in a covered container. Three or more cups per day are consumed immediately after meals. Three to five milliliters of tincture can also be used three times per day.