Only ten percent of all manuka honey is claimed to have antibacterial properties because of its non-hydrogen peroxide antibacterial content. This honey is known as NPA (Non-Peroxide Activity) manuka honey. According to German researcher Professor Thomas Henle, MGO, or methylglyoxal, found in high concentrations in manuka honey, is the antiseptic compound mostly responsible for NPA.

A 2002 review found that although the antibacterial activity of honeys (including manuka honey) had been demonstrated in vitro, the number of clinical case studies was small. It felt there was a potential for its usage in "the management of a large number of wound types".^[5] A 2008 Cochrane Review found that honey may help improve superficial burns compared to standard dressing, but there was insufficient evidence from studies, many of which were on manuka honey, to be conclusive, and the use of honey for leg ulcers provided no benefit. The review found that there was insufficient evidence for any benefit in other types of chronic wounds, as all of the data came from a single centre of research, and that "data from trials of higher quality found honey had no significant effect on healing rates or had significantly slower rates of healing".^[6]

Methylglyoxal (MGO) is the major antibacterial component of manuka honey.^[7] Other smaller antibacterial effects are expected to arise from the osmolarity and pH of the manuka honey.^[6] In vitro studies indicate methylglyoxal is an effective antimicrobial agent against forms of MRSA,^[8][9] but there is a lack of case studies on people.^[5][6]