Selection and Use of Honey on Wounds

P. C. Molan B.Sc. Ph.D.

Honey Research Unit, Department of Biological Sciences, University of Waikato, Hamilton, New Zealand

Honey is one of the oldest known medicines that has continued to be used up to present times in folk-medicine. Its use has been "rediscovered" in later times by the medical profession, especially for dressing wounds. The numerous reports of the effectiveness of honey in wound management, including reports of several randomised controlled trials, have recently been reviewed, rapid clearance of infection from the treated wounds being a commonly recorded observation.

In almost all of these reports honey is referred to generically, there being no indication given of any awareness of the variability that generally is found in natural products. Yet the ancient physicians were aware of differences in the therapeutic value of the honeys available to them: Aristotle (384-322 BC), discussing differences in honeys, referred to pale honey being "good as a salve for sore eyes and wounds"; and Dioscorides (c.50 AD) stated that a pale yellow honey from Attica was the best, being "good for all rotten and hollow ulcers".

Any honey can be expected to suppress infection in wounds because of its high sugar content, but dressings of sugar on a wound have to be changed more frequently than honey dressings do to maintain an osmolarity that is inhibitory to bacteria, as honey has additional antibacterial components. Since microbiological studies have shown more than one hundred-fold differences in the potency of the antibacterial activity of various honey, best results would be expected if a honey with a high level of antibacterial activity were used in the management of infected wounds.

Other therapeutic properties of honey besides its antibacterial activity are also likely to vary. An anti-inflammatory action and a stimulatory effect on angiogenesis and on the growth of granulation tissue and epithelial cells have been observed clinically and in histological studies. The components responsible for these effects have not been identified, but the anti-inflammatory action may be due to antioxidants, the level of which varies in honey. The stimulation of tissue growth may be a trophic effect, as nutrification of wounds is known to hasten the healing process: the level of the wide range of micronutrients that occur in honey also varies.

Until research is carried out to ascertain the components of honey responsible for all of its therapeutic effects it will not be possible to fully standardise honey to obtain optimal effectiveness in wound management. However, where an antiseptic wound dressing is required then standardisation for this effect is possible. Several brands of honey with standardised levels of antibacterial activity are commercially available in Australia and New Zealand, but even where these are not available it is possible to assay the level of antibacterial activity of locally available honey by a simple procedure in a microbiology laboratory.

The antibacterial activity of honey is due primarily to hydrogen peroxide generated by the action of an enzyme that the bees add to the nectar, but there are some floral sources that provide additional antibacterial components. The body tissues and serum contain an enzyme, catalase, that breaks down hydrogen peroxide - how much of the honey antibacterial activity is lost through this is not known. The antibacterial components that come from the nectar are not broken down by this enzyme. Until comparative clinical trials are carried out to determine which type of antibacterial activity is the more effective, it may be best to use manuka honey, as this contains hydrogen peroxide activity as well as the component that comes from the nectar.

Because the enzyme in honey that produces hydrogen peroxide is destroyed by heating and exposure to light, unpasteurised honey should be used, and it should be stored in a cool place and protected from light. If it is necessary to warm honey to liquefy it, it should be heated to no more than 37øC. If it is considered necessary to sterlise honey, this can be done by gamma-irradiation without loss of antibacterial activity. Gamma-irradiated manuka honey is available commercially. (In none of the clinical reports of use of honey on wounds was the honey used sterilised.No case of infection resulting from the use of honey has been reported.)

Manuka honey can have a uniquely high level of an antibacterial component from nectar that is not broken down by catalase. This antibacterial component is particularly effective against Staphylococcus aureus. Like all honeys, manuka honeys vary very much in their potency. A 'UMF' rating ('Unique Manuka Factor', equivalent to the % phenol with the same activity against Staphylococcus aureus) is being used by producers of manuka honey to show the potency of this antibacterial component, as more than half of the manuka honey on sale does not have any significant amount of this component present.

Some practical considerations are:

• Ensure that there is an even coverage of the wound surface with honey. Honey can be made fluid by stirring or warming. Cavities may be filled by pouring in fluidised honey, or more conveniently by using honey packed in squeeze-tubes. (Gamma-irradiated manuka honey in tubes is available commercially.)

• Spread honey on the dressing pad rather than on the ulcer - it is much easier to do and causes less discomfort for the patient.

• The amount of honey needed depends on the amount of fluid exuding from the wound - the benefits of honey on wound tissues will be reduced if honey becomes diluted a lot: typically, 20 ml of honey is used on a 10 cm X 10 cm dressing.

• Cover with absorbent secondary dressings to prevent honey oozing out from the dressing. Change the dressings more frequently if the honey is being diluted a lot - otherwise change every day or two.