Honey can be a useful treatment for wounds, but not all wounds require its use. So which ones will? Vet blogger Sian investigates…

Simple clean cuts

A simple laceration or recent clean cut will heal as quickly with salt water bathing. A weak salt solution or sterile saline can be used to clean wounds twice daily with flushing or gentle patting on kitchen roll or lint. There is no evidence that honey will speed healing in these wounds (1,2).

Complex, deep or infected wounds 

These, however, may benefit from the use of honey on a wound dressing alongside other management strategies. When a population of bacteria infect a wound, a slime is often formed of bacteria and inflammatory exudate (a biofilm). This can foster bacterial growth and slow healing as bacteria multiply and inflammation progresses, antibiotics may be unable to penetrate the slime. 

Honey has been used as a wound dressing for many years in human and veterinary medicine. Scientific research has found several biological properties that fight infection and promote healing(3). 

The pH

Honey has a low pH, in other words it is acidic, with the average being 3.9 (neutral is 7). Bacteria thrive in alkaline or high pH environments, so introducing an weakly acidic substance into a wound inhibits bacterial growth. An acidic environment also encourages the red blood cells in adjacent blood vessels to release oxygen creating an oxygen rich environment. Many bacterial species prefer low oxygen environments, so this discourages colonisation and growth. Finally, the low pH of honey inhibits the action of proteases. Proteases are enzymes that break down proteins and delay healing. Inflammation from primary damage or infection increases protease activity so inhibiting their action reduces this harmful effect of over-enthusiastic inflammation.

The Osmolarity

Honey is a very concentrated solution, so water flows from swollen surrounding tissues to dilute it. This removes some of the fluid that accumulates in inflamed tissue. Less swelling (oedema) means that cells can recover faster and new skin growth is accelerated. Fluid is also drawn out from inside bacteria, dehydrating and killing the organisms. As fluid flows into the honey solution, the surface of the wound remains moist. This can reduce the pain of wounds and it is more painful to change wound dressings when the wound dries out. A moist wound will also heal faster as cells can multiply more quickly to fill in the gaps.

Enzymatic action

Bee saliva contains an enzyme called glucose oxidase. When a bee extracts nectar from a flower this salivary enzyme mixes with the nectar. The enzyme breaks glucose down to gluconic acid releasing hydrogen peroxide as a product of the reaction. Hydrogen peroxide is widely used as a disinfectant and steriliser as it has a broad spectrum of action against microbes. Unfortunately, it can be deactivated by the enzyme catalase which can be found in wounds.

Does the type of honey matter?

There are over 300 types of honey in the world. The nectar source determines their qualities. Manuka honey is made by a population of bees in New Zealand who feed in Manuka flowers. This is believed to be the most effective honey for wound dressings. Medical grade honey is usually Manuka honey as it’s antibacterial properties surpass the production of hydrogen peroxide. A chemical in Manuka nectar called dihydroxyacetone becomes methylglyoxal (MGO) in honey. Low concentrations of MGO inhibit bacterial growth and movement and higher concentrations dehydrate bacteria. It is not inhibited by the enzyme catalase so is more effective in wounds even when inflammatory fluid or exudate is present. 

There is also strong evidence that honey stimulates the immune response, encouraging new skin growth and suppressing inflammation(3). The hygroscopic action of attracting water dries out necrotic or dead tissue resulting in easier removal so fresh skin can cross the defect. 

Honey is a useful substance for wound management. 

Firstly, the type of wound must be suitable for this treatment. Simple wounds do not benefit from the use of honey, but it can be synergistic with other wound care management in complex or infected wounds. 

Secondly, the right type of honey should be used. Honey stored in your kitchen cupboard could introduce contaminants when applied to a wound. Processing methods used in honey produced for human consumption often deactivate enzymes and reduce the osmolarity or concentration. Medical grade honey is sterilised for safe use in wounds, but any processing is designed to keep the natural antibacterial and anti-inflammatory properties. 

Most of the research in the veterinary use of honey in wounds is presented in case reports. At this time there are no large-scale studies on the use of honey in wound care. As antibiotic resistance becomes more common in animal species, honey will be an effective weapon in our wound care armoury. 

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References

  1. Marcombes L. Does the use of topical honey result in a faster rate of second intention wound healing in dogs? (2020) Veterinary Evidence Knowledge Summaries 5(4)
  2. Brennan M and Belshaw Z. Does Manuka honey improve the speed of wound healing in dogs? (2020) Vet Record 187:1
  3. Molan P and Rhodes T. Honey: A biologic wound dressing. (2015) Wounds 27 (6): 141-151