Herpes is a virus so common among humans that adult infection rates have been estimated from 60% to 95% of the world population, varying according to socioeconomic conditions.
This estimate includes both Herpes simplex 1 (HSV-1 called oral Herpes or cold sores) and Herpes simplex 2 (HSV-2 or genital Herpes).
A herpes infection may become asymptomatic when dormant, then become reactivated during environmental or physiological stress from time to time.
Many studies have explored the possible use of lemon balm for preventive or therapeutic activity against herpes infections, including HSV-1, HSV-2, and acyclovir-resistant herpes.
Early research showed virucidal effects of Melissa officinalis lemon balm extracts as early as three hours after treatment and inactivation of the virus within 24 hours (Dimitrova Z: Antiherpes effect of Melissa officinalis L. extracts, Acta Microbiol Bulg 1993, p65-72).
An early cell study tested lemon balm essential oil against HSV-2 using Hep-2 cells.
While the lemon balm essential oil was an effective inhibitor of viral replication and nontoxic to the cells at low concentrations, it became slightly toxic at concentrations higher than 100 microg/ml (Allahverdiyev A et al: Antiviral activity of the volatile oils of Melissa officinalis L. against Herpes simplex virus type-2, Phytomedicine November 2004, p657-61).
A cell study in 2008 showed that lemon balm essential oil was effective against both HSV-1 and HSV-2.
When the oil was applied at an extremely low concentration (noncytotoxic), infection as measured by plaque formation was
reduced by 98.8% for HSV-1 and
reduced by 97.2% for HSV-2.
At higher concentrations, infection was almost completely eliminated.
The oil worked directly on the herpes virus and was effective in preventing the virus from attaching to the cell, but did not affect the virus that had already penetrated the cell.
The authors suggested that it may be useful as a topical application against herpes skin infections (Schnitzler P et al: Melissa officinalis oil affects infectivity of enveloped herpesviruses, Phytomedicine September 2008, p734-40).
In contrast, a study using the hydroalcoholic extract of lemon balm leaves found that it was an effective inhibition against HSV-2 but did not prevent the entry of the virus into the tested cells (Mazzanti G et al: Inhibitory activity of Melissa officinalis L. extract on Herpes simplex virus type 2 replication, Nat Prod Res 2008, p1433-40).
A study in 2012 tested the water extract of lemon balm and some of its chemical components, finding that the complete extract was effective against HSV-1 at very low concentrations, while the separate chemicals required concentrations 100 times higher to show similar effectiveness.
Again the study confirmed that lemon balm extract showed direct virus-killing action and prevented the virus from attaching to host cells (Astani A et al: Melissa officinalis extract inhibits attachment of herpes simplex virus in vitro, Chemotherapy (58) 2012, p70-7).
An increasing problem with antibiotic prescription drugs for viral and bacterial infections is the development of drug resistance leading to the development of more deadly infections.
Consequently, researchers are exploring various plant extracts and oils that have a reputation of preventing or treating infection over thousands of years of usage without the development of apparent resistance.
One of the plants they are exploring is Melissa officinalis or lemon balm as an extract and essential oil.
Using water extracts from lemon balm and other herbs in the Lamiaceae family (sage, thyme, rosemary, peppermint, and prunella or self-heal), a 2006 study found high virucidal activity for all extracts against HSV-1, HSV-2, and acyclovir-resistant strain of HSV-1 using RC-37 cells.
When using the maximum concentrations that were not toxic to the cells, the researchers found plaque formation decreased by up to 90% with greater effects when tested after longer periods of time.
There was no effect on viral replication within the cell indicating that the benefits occurred with freely circulating virus (Nolkemper S et al: Antiviral effect of aqueous extracts from species of the Lamiaceae family against Herpes simplex virus type 1 and type 2 in vitro, Planta Med December 2006, p1378-82).
A 2014 study confirmed that Melissa lemon balm extract interacted with the freely circulating virus of two acyclovir-resistant HSV strains and inhibited viral attachment to cells up to 96% with low toxicity concentrations (Astani A et al: Attachment and penetration of acyclovir-resistant herpes simplex virus are inhibited by Melissa officinalis extract, Phytother Res October 2014, p1547-52).
Human studies tested standardized topical skin creams containing 1% dried extract from lemon balm leaves.
A multi-center study tested 116 herpes simplex or HSV-1 patients in a placebo-controlled double-blind study and found that a topical application of the dried extract of lemon balm was effective, especially when applied at the very early stages of infection (Wolbling RH and Leonhardt K: Local therapy of herpes simplex with dried extract from Melissa officinalis, Phytomedicine June 1994, p25-31).
In another study, 66 patients were treated with the lemon balm skin cream and compared to a placebo cream with applications over a five day period with four applications daily.
The lemon balm skin cream showed statistically significant improvement by shortening the healing time, preventing the infection from spreading, and rapidly reduced symptoms of pain, redness, itching, and swelling.
Healing was reported to be very good for 41% of the lemon balm ointment users and 19% for the placebo ointment users (Koytchev R et al: Balm mint extract (Lo-701) for topical treatment of recurring herpes labialis, Phytomedicine October 1999, p225-30).
One study tested commercial tinctures and found they contained from 2 to 22 times more rosmarinic acid compared to the tinctures made from fresh plant leaves, which may be important for the treatment of Herpes simplex (Sanchez-Medina A et al: Comparison of rosmarinic acid content in commercial tinctures produced from fresh and dried lemon balm (Melissa officinalis), J Pharm Pharm Sci 2007, p455-63).
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