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Honey in wound care: understanding the evidence

Honey has been used in wound management for centuries and clinical research suggest that its antimicrobial properties can stimulate the healing process. Georgina Gethin explains …

Georgina Gethin
PhD RGN HE Dip Wound Care
Lecturer
Research Centre
Faculty of Nursing and Midwifery
Royal College of Surgeons in Ireland

Wound management practice, which includes the use of dressings such as honey, should be based on the most up-to-date evidence generated through methodologically sound research studies. In the absence of well-designed clinical trials, evidence is based on case studies, case series, consensus opinion and experience.
Honey has been used in wound management for centuries and the literature reports case studies and the first clinical trials of honey in 1944.(1) Its use declined after this time mainly due to the more widespread use of antibiotics, antiseptics and improved surgical techniques. There was a shift in the late 1960s towards the development of more "modern" dressings and thus honey as a wound management product lost favour with practitioners. However, since the late 1980s, there has been renewed interest. Today case studies and clinical trials have been more specific as they show that not all honeys are the same: some are more advantageous to wound healing than others.(2,3)

Composition of honey
Honey is not a generic agent. It is composed of at least 80% sugars with approximately 17% water. The remainder is made up of trace elements, acids, enzymes and other compounds.4 A cursory glance at honey will show the difference in colour, viscosity and smell. The differences in honey are due to the floral source, the foraging bee and the geographical location from which it is sourced. Darker honeys are higher in antioxidants than lighter honeys and tend to be from the Southern hemisphere, particularly New Zealand and Australia. Examples are Manuka honey made from the Leptospermum scoparium bush, which grows wild throughout these countries and has a pH in the range of 3.5-4.5, making it quite acidic. Manuka is the Maori name given to the Leptospermum bush.

Clinical applications
One of the most frequent characteristics attributed to honey is its antibacterial properties. Laboratory work has shown distinct differences in the antibacterial activity depending on the type of honey that is used.(2,3,5,6) This characteristic is due to many factors:

  • Its high osmotic effect.
  • The low pH.
  • Hydrogen peroxide activity.
  • Some as yet unidentified phytochemical agents.

Honey is a highly osmolar substance, meaning that it has the ability to draw water to it. This effect deprives bacteria of available water necessary for reproduction and also serves to aid wound cleansing as water is drawn from the deeper wound compartments to the surface.(7) This further contributes to reducing the bacterial burden as it removes the environment that favours proliferation. The pH of honey is usually in the range of 3.5-4.5 although some regions in Pakistan report a pH of up to 6.3.8 Bacteria are pH sensitive and reproduce at specific pH ranges. The low pH of honey does not facilitate proliferation of some species, thus contributing to reducing the bacterial load of the wound.
Hydrogen peroxide naturally occurs in honey but at a much lower concentration than that traditionally used as a wound cleansing agent. Honey contains an enzyme called glucose oxidase, which converts glucose to gluconic acid and hydrogen peroxide. This hydrogen peroxide kills bacteria. However, an enzyme normally found in wound fluid called catalase degrades the hydrogen peroxide so that it is no longer antibacterial. Studies have shown that Manuka honey continues to kill bacteria even when the hydrogen peroxide is removed.(2,5,6,9) The cause of this latter effect is as yet unknown and is referred to as "unidentified phytochemical agents". This effect has been demonstrated against a range of common wound-colonising pathogens including Staphylococcus aureus, methicillin-resistant Staph aureus (MRSA), methicillin-susceptible Staph aureus (MSSA) and pseudomonas, and recently against community-acquired MRSA.(3)
The clinical work that explores the use of honey has increased with research at all levels of the evidence ladder. In the treatment of burns, several studies from India using a local honey have reported greater efficacy when compared with silver sulphadiazine, amniotic membrane and film dressings.(10-12) No studies of burns that included honey have been reported outside of India. In the management of toe nail avulsion two trials that compared honey with iodine or paraffin tulle did not demonstrate superiority of honey over the comparator.(13,14) The honey used was a Manuka honey and a mixed flora honey that included Manuka. These studies did not report any adverse events when honey was used.
Two large randomised controlled trials investigated the use of Manuka honey in venous ulceration.(15,16) One involved 368 patients and did not show any additional benefit when Manuka honey was used in combination with compression therapy versus compression and usual care.(15) However, of interest from this study was that those treated with honey were treated more cost-effectively when all factors were considered than those in the usual care group. This may have implications for clinical practice.
The second study investigated the use of Manuka honey in venous ulcers in which more than 50% of the wound area was covered in slough.(16) This study reported improved healing outcomes at 12 weeks when honey was used in comparison to a hydrogel. The median reduction in wound size after four weeks was also significantly better in the Manuka honey group. Honey effectively desloughed the wounds and in addition the number of cases of wound infection was less in those treated with Manuka honey (n=6) versus those treated with hydrogel (n=12). In all cases compression therapy was continued. This study differed from the previous one in that wounds were larger and of longer duration and the wound bed was compromised by the presence of slough.
A plethora of case studies have demonstrated efficacy of honey in a wide range of wound aetiologies such as pressure ulcers, rheumatoid ulcers, lacerations and abscess.(17,18) One large study of 40 patients aimed to elicit the acceptability of the use of the product. Patients reported a high satisfaction with the use of honey.(19) While there were reports of pain, it is worth noting that pain was most often associated with wounds of longer duration, larger size and previous poor response to treatment.(19) Case series studies do not demonstrate a cause and effect relationship but can add to knowledge about the practical use of any product, including honey. Some of the practical issues are dealt with here and include application, pain, malodour, exudates and safety.

Practical considerations
Application
Honey can be applied either as a topical ointment or as a dressing. As an ointment the honey is best applied to a secondary dressing such as a foam or alginate, which is then placed on the wound. The secondary dressing should take account of the level of exudate from the wound and be capable of handling such exudate. Honey dressings also require a secondary dressing as no island dressings of honey have as yet been made. These are simply applied to the wound and changed as required. In some of the studies the dressing changes were weekly demonstrating that they can be used in a similar way to other regimes. However, some authors advocate more frequent dressing change.(20) Frequency of change should be based on the condition of the wound bed, as with any other product.
Pain
There is a lack of consensus in the literature with regards to pain associated with the use of honey.(15,17,19,21) Some studies report an increase in pain while others show a significant reduction. However, it should be noted that these studies often do not report the method of pain assessment and time of assessment, thus making interpretation of findings more difficult. Personal experience with the use of honey has demonstrated that honey can be painful in wounds that are arterially compromised. This may be due to the highly alkaline nature of the wounds and the osmotic effect suddenly placed on the wound bed. Newer products in development are attempting to change the pH to overcome this problem. Therefore, while honey is not contraindicated in arterial wounds, its use may be too painful for some individuals and an alternative should be considered.

Odour control
Many case studies have recorded the positive impact that the use of honey dressings have on managing malodorous wounds.(17,22,23) Malodour may be due to bacterial proliferation and may indicate infection. This should be investigated and any underlying infection treated appropriately. However, some wounds such as fungating lesions and chronic ulcers are malodorous in the absence of infection. Topically-applied honey-based dressings may prove beneficial in these cases.
One of the more interesting characteristics of honey is its naturally low pH. Wounds heal in an acid environment and indeed nonhealing chronic wounds have been shown to have an elevated alkaline environment.(24) This alkalinity has also been demonstrated in skin grafts that have failed to "take". As an acidic agent it was proposed that the application of honey could contribute to lowering the pH of chronic wounds. One study demonstrated such an effect with pH lowering over two weeks and an additional reduction in wound size.(24) This latter study demonstrated that a reduction of 0.1 pH unit was associated with an 8.1% reduction in wound size. The study was confined to nonhealing chronic wounds of varying aetiology and included venous, arterial, mixed aetiology and diabetic foot ulcers.
Many clinicians are concerned about the use of honey in patients with diabetes. We have reported cases of topical honey in diabetic foot ulcers without any adverse effects to the patients.(17,25) In these cases, close monitoring of serum glucose levels using routine "finger prick" analysis was conducted. It is advised that if wounds are very large, topical honey should be used with caution and close monitoring is advised.
Safety is of concern for all professionals involved in patient care. Food grade honey is not a sterile product, and may be naturally contaminated with several organisms that if applied to wounds, may actually act as inoculums of potentially pathogenic skin pathogens to the wound.(3,26) Therefore clinicians should only consider the use of honey preparations that have been sterilised so that no residual microflora remains to act as potential inoculants to bacterial organisms.
Honey is now available in sterilised dressings or tubes licensed for use in wound management. At a minimum this ensures clinicians are using a safe product.

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References

  1. Temnov VA. Bactericidal properties of honey and utilization of honey and other bee-keeping products for the healing of wounds. Bee World 1944;25:86-7.
  2. Allen KL, Molan PC, Reid GM. The variability of the antibacterial activity of honey. Apiacta 1991;26:114-21.
  3. Maeda Y, Loughrey A, Earle JA, et al. Antibacterial activity of honey against community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Complement Ther Clin Pract 2008;14:77-82.
  4. National Honey Board. Honey, a reference guide to natures sweetener. 2005. Available from: http://www.nhb.org
  5. Cooper R, Molan P, Harding KG. Antibacterial activity of honey against strains of Staphylococcus aureus from infected wounds. J R Soc Med 1999;92:283-5.
  6. Cooper R, Molan P, Harding KG. The sensitivity of honey to Gram-positive cocci of clinical significance isolated from wounds. J Appl Microbiol 2002;93:857-63.
  7. Chirife J, Herszage L. Sugar for infected wounds. Lancet 1982;2:157.
  8. Kamal A, et al. Comparative study of honey collected from different flora of Pakistan. Online J Biol Sci 2002;2:626-7.
  9. Molan P. The antibacterial activity of honey. 2. Variation in the potency of the antibacterial activity. Bee World 1992:73:59-76.
  10. Subrahmanyam M. Topical application of honey in treatment of burns. Br J Surg 1991:78:497-8.
  11. Subrahmanyam M. Honey-impregnated gauze versus amniotic membrane in the treatment of burns. Burns 1994;20:331-3.
  12. Subrahmanyam M. Honey impregnated gauze versus polyurethane film (OpSite) in the treatment of burns - a prospective randomised study. Br J Plast Surg 1993:46;322-3.
  13. McIntosh CD, Thomson CE. Honey dressing versus paraffin tulle gras following toenail surgery. J Wound Care 2006;15:133-6.
  14. Marshall C, Queen J Manjooran J. Honey v povidine iodine following toenail surgery. Wounds UK 2005;1:10-8.
  15. Jull A, et al. Randomized clinical trial of honey-impregnated dressings for venous leg ulcers. Br J Surg 2008;95:175-82.
  16. Gethin G, Cowman S. Manuka honey vs hydrogel, a prospective, open label, multicentre randomised controlled trial to compare desloughing efficacy and healing outcomes in venous ulcers. J Clin Nurs 2008; in press.
  17. Gethin G, Cowman S. Case series of use of Manuka honey in leg ulceration. Int Wound J 2005;2:10-5.
  18. Van der Weyden EA. The use of honey for the treatment of two patients with pressure ulcers. Br J Community Nurs 2003;8:S14-20.
  19. Dunford CE, Hanano R. Acceptability to patients of a honey dressing for non-healing venous leg ulcers. J Wound Care 2004;13:193-7.
  20. Molan P, Betts J. Clinical usage of honey as a wound dressing: an update. J Wound Care 2004;13:353-6.
  21. Gethin G, Cowman S. Bacteriological changes in sloughy venous leg ulcers treated with manuka honey or hydrogel: an RCT. J Wound Care 2008;17:241-7.
  22. Kingsley A. The use of honey in the treatment of infected wounds: case studies. Br J Nurs 2001;10:S13-4.
  23. Hejase MJ, Hejase MJ, Simonin JE, Bihrle R, Coogan CL. Genital Fournier's gangrene: experience with 38 patients. Urology 1996;47:734-9.
  24. Gethin G, Cowman S, Conroy R. The impact of Manuka honey dressings on surface pH of chronic wounds. Int Wound J 2008;5:185-95.
  25. Abdelatif M, Yakoot M, Etmaan M. Safety and efficacy of a new honey ointment on diabetic foot ulcers: a prospective pilot study. J Wound Care 2008;17:108-10.
  26. Postmes T, van den Bogaard AE, Hazen M. The sterilization of honey with cobalt 60 gamma radiation: a study of honey spiked with Clostridium botulinum and Bacillus subtilis. Experentia 1995;51:986-9.

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"In the arab muslim world we have used honey as a medicine for more than 1,400 years because it is mentioned in our Holy Quran as a medicine for all diseases." - Amoona Rayan