How effective is lemon balm at treating herpes sores?

There are two types of herpes simplex virus (HSV): HSV-1 and HSV-2. Following the initial infection, HSV often becomes chronic, causing recurrent outbreaks of sores in either the oral or genital areas. Oral herpes is typically, but not always, caused by HSV-1; genital herpes is typically, but not always, caused by HSV-2. The sores (in oral herpes, “cold sores”) are often preceded by a tingling sensation, followed by blistering, which can be quite painful. The sores will resolve on their own without treatment in 2 to 3 weeks. There is no cure for HSV infection, but the duration of the sores can be reduced by treatment with oral or topical (applied to the skin) antiviral medication at the first sign of an outbreak; in people who have frequent outbreaks or are immunocompromised, the frequency of outbreaks may be reduced with longer courses of oral antivirals.^[1][2]

Many people with HSV use a commercial over-the-counter cream containing 1% dried lemon balm extract to treat oral or genital herpes sores.^[3] Two randomized, placebo-controlled trials of lemon balm cream for herpes sores have been published in English; the cream was moderately effective compared to the placebo.^[4][5][6] The first one, a 1994 trial in Germany in 115 people with oral or genital herpes who applied either 1% lemon balm cream or a placebo to the affected skin 2–4 times daily for 5–10 days, found that the cream reduced second-day redness and swelling, but not scabbing, lesion size, the number of blisters, or pain, compared to the placebo; additionally, more participants in the lemon balm group were judged to have healed well by 5 days than in the placebo group.^[6] The second, a 1999 trial in Bulgaria in 66 people with oral herpes who applied either lemon balm cream or a placebo 4 times a day for 5 days, found that the people who used the lemon balm had lower combined symptom scores on day 2 than people using the placebo, but the difference by day 5 was not significant.^[5] To summarize, based on the limited available research, lemon balm cream appears to be moderately effective for HSV sores and may ease the course of an outbreak.

Not much research has directly compared lemon balm to prescription antiviral medications. Topical lemon balm may be better at reducing pain than topical acyclovir, but slower to promote healing, according to a 2015 study in 60 people in Iran with oral herpes. The study compared the effectiveness of applying a lemon balm gel to the affected areas for seven days to that of applying acyclovir 5% cream. Both groups of participants had similar reductions in lesion size after seven days, but the lemon balm group reported less pain, and the lesions in the acyclovir group shrank much more quickly.^[7] However, it’s unclear from the study’s write-up when the treatments were applied — treatment is most effective before blisters appear, or at the latest within 48 hours of their appearance^[8] — or how often they were applied. Furthermore, oral antiviral medications are more effective than topical ones^[8] and are currently the standard of care for oral herpes.^[1] Although more research is needed, the current picture favors prescription oral antivirals over lemon balm.

Lemon balm has not been clinically studied for any of the many other manifestations of HSV infection, and should not be used to treat them. Other manifestations of herpes, including but not limited to ocular (eye) HSV, neonatal herpes, herpes encephalitis, and chronic severe HSV, can be serious and even fatal;^[1] medical attention should be sought.