In clinical practice, lemon balm is often prescribed in combination with other herbal medicines. As a reflection of this, many clinical studies have investigated the effects of lemon balm as an ingredient of a herbal combination, making it difficult to determine the efficacy of this herb individually.
Although used traditionally as a treatment for anxiety, most modern-day evidence comes from in vivo studies, as the herb has not been clinically tested to a significant degree. However, the essential oil of lemon balm has been investigated under double-blind placebo-controlled conditions and found to be a safe and effective treatment for clinically significant agitation in people with severe dementia. The trial, which involved 71 subjects, found that after 1 month’s treatment, patients were less agitated, less socially withdrawn and spent more time in constructive activities than those in the placebo group.
Lemon balm has been used for centuries to improve cognitive function and encouraging results from a 2002 clinical study confirm that it can influence memory.
The randomised, double-blind crossover study involving 20 healthy young volunteers found that single doses of lemon balm were able to modulate both mood and cognitive performance in a dose- and time-dependent manner. In this study, treatment with the lowest dose (300 mg) increased self-rated ‘calmness’ within 1 hour whereas the 600 mg and 900 mg doses produced significant effects on memory task performance, observable at both 2.5 hours and 4 hours after administration. The highest tested dose (900 mg) was found to significantly reduce alertness within 1 hour, suggesting a dose-response effect.
A randomised, double-blind, placebo-controlled trial demonstrated the efficacy and safety of Melissa officinalis in 42 patients aged 65-80 with mild to moderate Alzheimer’s disease who were given 60 drops/day for 4 months. Outcome measures included significantly better cognition and reduced agitation.
In clinical practice, lemon balm is often prescribed in combination with other herbs such as valerian in the treatment of insomnia. As a reflection of this, a randomised, double-blind multicentre study investigated the effects of a commercial valerian and lemon balm herbal combination (Songha Night) in 98 healthy subjects. Treatment was administered over a 30-day period and consisted of 3 tablets taken half an hour before bedtime, providing a total dose of 1-6 g valerian and 1-2 g lemon balm. Herbal treatment was found to significantly improve sleep quality and was well tolerated.
Another randomised, double-blind crossover study found that the same combination of valerian and lemon balm taken over 9 nights was as effective as triazolam in the treatment of insomnia. The dose used was equivalent to 1.4 g dried valerian and 0.9 g dried lemon balm.
As with all herbal combination studies, it is difficult to determine the contribution each individual herb made to the end result. As such, these studies are encouraging but the role of lemon balm as a stand-alone treatment for insomnia remains unclear.
Commission E approves the use of lemon balm in the treatment of insomnia.
GASTROINTESTINAL CONDITIONS ASSOCIATED WITH SPASM AND NERVOUSNESS
To date, only studies using lemon balm in combination with other herbs are available.
A 15-day open study involving 24 subjects with chronic non-specific colitis investigated whether a combination of lemon balm, St John’s wort, dandelion, marigold and fennel could provide symptom relief. Excellent results were obtained by the end of the study, with herbal treatment resulting in the disappearance of spontaneous and palpable pains along the large intestine in 95.83% of patients. A double-blind study using a herbal tea prepared from chamomile, lemon balm, vervain, licorice and fennel in infantile colic has also been conducted. A dose of 150 mL offered up to three times daily was found to eliminate symptoms of colic in 57% of infants, whereas placebo was helpful in only 25% after 7 days’ treatment.
Commission E supports the use of lemon balm for functional gastrointestinal conditions.
HERPES SIMPLEX TYPE I — EXTERNAL USE
The topical use of lemon balm preparations for HSV infection is very popular in Europe. Results from a randomised double-blind study in 55 subjects with a history of recurrent herpes labialis (>3 episodes/year) found that standardised lemon balm ointment (700 mg crude herb per gram) applied four times daily for 5 days significantly shortened healing time, prevented infection spread and produced rapid symptom relief. Decreased symptoms and increased rate of healing were also observed in another double-blind study of lemon balm cream in 115 subjects.
Lemon balm: Other Uses
Animal studies have identified a dose-dependent anti-ulcerogenic activity for lemon balm extract, which has been histologically confirmed. This activity is associated with a reduced acid output and an increased mucin secretion, an increase in PGE2 release and a decrease in leukotrienes.
Lemon balm: Dosage Range
• Fresh herb: 1.5-4.5 g two-three times daily.
• Infusion: 1.5-4.5 g in 150 mL water.
• Fluid extract (1:1) (g/mL): 5-12 mL/day.
• Ointment: 700 mg/g ointment applied four times daily for herpes simplex infection.