Lemon balm is well tolerated according to one double-blind, randomised crossover study.
Controlled clinical studies are not available, so interactions are speculative and based on evidence of activity.
Increased sedative effects: one animal study found that concomitant administration of lemon balm extract with pentobarbital produced an increased sedative effect — observe patients taking this combination.
Additive effects are theoretically possible and may be beneficial — observe patients taking this combination.
Contraindications and Precautions
Hypothyroidism — one in vitro study found that an extract of Melissa officinalis inhibited both the extrathyroidal enzymic T4-5′-deiodination to T3 and the T4-5′-deiodination. Whether this has any clinical significance has yet to be determined.
Safety has not been scientifically established and is unknown.
Practice Points / Patient Counselling
• Lemon balm has been used traditionally to treat insomnia, irritability, restlessness, anxiety and dementia. It is also used to relieve gastrointestinal symptoms associated with spasms and nervousness.
• Used topically as a cold sore treatment, it significantly reduces symptoms, shortens the healing period and prevents infection spread. It may be suitable both as an active treatment and as a preventative agent in cases of chronic recurrent herpes simplex infections.
• The essential oil is used in aromatherapy to relieve anxiety and promote calm and a sense of wellbeing, which has been confirmed in one clinical study.
• One clinical study has found that it can modulate both mood and cognitive performance in a dose- and time-dependent manner.