Lemon balm (Melissa officinalis) is a perennial herb in the mint family Lamiaceae, native to southern Europe and the Mediterranean region. Lemon Balm is used medicinally as a herbal tea, or in extract form. It is claimed to have antibacterial, antiviral properties (it is effective against herpes simplex), and it is also used as a mild sedative or calming agent. At least one study has found it to be effective at reducing stress, although the study's authors call for further research. Its antibacterial properties have also been demonstrated scientifically, although they are markedly weaker than those from a number of other plants studied.
Parameswari, G.; Meenatchisundaram, S.; Subbraj, T.; Suganya, T.; and Michael, A.
"Note on Pharmacological Activities of Melissa officinalis L.,"
Ethnobotanical Leaflets: Vol. 2009
, Article 25.
Available at: http://opensiuc.lib.siu.edu/ebl/vol2009/iss1/25