Does lemon balm have any drug interactions?

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There are no clinical reports of drug interactions with lemon balm, but theoretical interactions include increased sedation with sedatives and reduced effectiveness of selective serotonin reuptake inhibitors (SSRIs) and thyroid hormone replacement. Additionally, lemon balm may inhibit certain enzymes that are involved in drug metabolism, though no adverse reports have been documented.

There aren’t any clinical reports of drug interactions with lemon balm. However, it has the following theoretical drug interactions:[1][2][3]

Drug or classPotential InteractionEvidence
SedativesMay increase sedationPre-clinical and initial human research
BarbituratesMay increase hypnotic (sleep-inducing) effectAnimal studies
Drugs that enhance or inhibit cholinergic activityBinds to muscarinic and nicotinic receptors receptors (clinical relevance not determined and effect likely varied)In vitro research[4]
Selective serotonin reuptake inhibitors (SSRIs)May reduce effectivenessIn vitro research
Thyroid hormone replacementMay reduce effectivenessIn vitro and animal research

Additionally, there’s in vitro evidence that one component of lemon balm, rosmarinic acid, may inhibit some of the enzymes also used to process drugs: cytochrome P450 (CYP450) enzymes CYP2C19 and CYP2E1, and UDP-glucuronosyltransferases (UGTs) UGT1A1, UGT1A6, and UGT2B7. This could theoretically affect the metabolism of any prescription drugs processed by these enzymes, although there have been no reports of this to date.[5][3]

References
1.^Ulbricht C, Brendler T, Gruenwald J, Kligler B, Keifer D, Abrams TR, Woods J, Boon H, Kirkwood CD, Hackman DA, Basch E, Lafferty HJ, Natural Standard Research CollaborationLemon balm (Melissa officinalis L.): an evidence-based systematic review by the Natural Standard Research Collaboration.J Herb Pharmacother.(2005)
2.^Posadzki P, Watson L, Ernst EHerb-drug interactions: an overview of systematic reviews.Br J Clin Pharmacol.(2013 Mar)
3.^Draginic N, Jakovljevic V, Andjic M, Jeremic J, Srejovic I, Rankovic M, Tomovic M, Nikolic Turnic T, Svistunov A, Bolevich S, Milosavljevic IMelissa officinalis L. as a Nutritional Strategy for Cardioprotection.Front Physiol.(2021)