Several supplements have been studied for cold sores, including lemon balm and honey. Some studies compare the treatment to a placebo ointment, gel, or cream with no active ingredients. Others compare the treatment to topical (on the skin) antiviral cream. With the latter studies, it’s worth remembering that topical antiviral cream isn’t the standard of medical care, because prescription oral antivirals are more effective. In other words, just because a supplement is better than a placebo or as good as antiviral cream doesn’t mean it’s the best treatment: An oral antiviral may be more effective. Unfortunately, no studies have compared supplements to oral antiviral medication.
A cream containing 1% dried lemon balm extract has been tested to treat oral or genital herpes sores and appears to be moderately effective compared to a placebo at reducing the severity of symptoms on the second day.[1][2] Little research has directly compared lemon balm to prescription antivirals; one randomized controlled trial (RCT) found that lemon balm cream reduced symptoms on the second day more than topical acyclovir (an antiviral) but was otherwise comparable.[3] Prescription oral antivirals are likely more effective.
Honey and propolis have also been studied for cold sores.[4] In a meta-analysis of three different RCTs comparing 0.5%–3% propolis ointment to acyclovir cream, the participants who used propolis were more likely to be completely healed by the 7th day of an outbreak than the participants who used acyclovir.[5] And in a meta-analysis of three RCTs comparing honey to acyclovir cream, honey healed cold sores faster than acyclovir cream, with an equivalent reduction in pain to acyclovir cream, although there was quite a lot of variability between the three studies and one of them had a high risk of bias.[5] Again, because prescription oral antivirals are superior to topical acyclovir, they’re likely more effective than honey. More research needs to be done to determine how propolis cream would compare to prescription antiviral medicine.