Honey may be an ancient natural remedy against many ills, but maybe it's time to consider bringing it back to combat cold sores, says Rod Tucker
The first written reference to the use of honey dates back to 2100-2000 BC, where it was mentioned in Sumerian texts as a drug and an ointment. Honey is predominately a mixture of two sugars; fructose and glucose (roughly 75%) and derived from nectar gathered by honey bees. In addition to sugar, honey also contains at least 181 other substances including enzymes, amino acids, proteins, flavonoids and phenolic compounds.
Honey has historically been used for its antibacterial action for the treatment of wounds and burns. In recent years, there has been interest in a honey from the manuka tree (manuka honey), which grows in New Zealand and eastern Australia and which has been commercialised as medihoney.
The reason for honey’s antibacterial action has been attributed to several factors including its acidic pH, osmolarity (which essentially ‘dehydrates’ bacteria) and the production of hydrogen peroxide. Interestingly, the antibacterial action of manuka honey is not attributed to hydrogen peroxide but thought to be related to its concentration of methylglyoxal (MGO).
Much less is known about the antiviral activity of manuka honey, though the available evidence is positive. For instance, one small in vitro study found that manuka honey was able to inhibit the influenza virus.
Another in vitro study using the herpes simplex virus-1 (HSV-1), which causes herpes labialis (ie cold sores), demonstrated that manuka honey and aciclovir had the highest inhibitory effect on HSV-1. The other herpes virus (herpes simplex virus-2, HSV-2) causes genital herpes and one study in 16 people infected found that treatment with locally collected honey in the United Arab Emirates was more effective than aciclovir.
Finally, in a study of children with herpetic gingivostomatitis (which is primarily caused by HSV-1), children given both local and commercial honey in combination with aciclovir suspension had a significantly earlier resolution of lesions compared to aciclovir alone.
The kanuka tree is botanically related to the manuka tree and the honey produced from has also been commercialised as Honevo. This type of honey is likely to have the same antibacterial/viral spectrum. It was therefore interesting to read a recent study in the British Medical Journal (BMJ) comparing kanuka honey with aciclovir in the treatment of herpes labialis.
This large randomised control trial included over 900 people recruited from community pharmacies who sought advice and treatment for a cold sore. Patients received either 5% aciclovir cream or 90% kanuka honey and were asked to apply the respective cream five times a day for up to 14 days. The study authors set the primary outcome measure as the healing time from randomisation to normal skin. There was no difference in the primary outcome between the two treatments: both were effective after eight to nine days.
While the results of the trial are interesting, the study lacked of a control group and it is known that herpes labialis infections normally resolve without any problems after seven to 10 days, which raises an even bigger question over whether pharmacists should actually be offering treatment for the condition.
Although there are reports of increasing resistance to the aciclovir, this is only a concern among immunocompromised patients who use the drug for extended periods of time and not known to be a problem when used in the short-term.
So, should pharmacists be recommending honey for cold sores? The medical grade (eg medihoney and Honevo) honeys used in studies are considerably more expensive than aciclovir and current advice is that topical antiviral creams should not be used due to the self-limiting nature of cold sores.
Honey would be a suitable alternative to antiviral agents if resistance to these agents becomes a problem. However, given that in practice, topical antiviral usage is limited to a few days, resistance this is unlikely to occur for a long time.