From the Guidelines
Methylene blue should not be used on the skin as an antiseptic or staining agent without caution, and its use is generally not recommended for skin applications due to potential side effects and the availability of safer alternatives. The provided evidence does not support the use of methylene blue for skin applications, and most studies focus on its use in diagnosing and treating conditions such as methemoglobinemia or as a staining agent in endoscopy 1. When considering the use of methylene blue, it is essential to weigh the potential benefits against the risks, including skin irritation, allergic reactions, and the potential for worsening methemoglobinemia in patients with G6PD deficiency 1.
For antiseptic purposes, other agents like povidone-iodine or chlorhexidine are typically preferred in clinical settings due to their efficacy and safety profiles. Methylene blue's antiseptic properties, which generate reactive oxygen species to damage bacterial cell membranes and DNA, are not sufficient to recommend its use on the skin without careful consideration of alternative options.
Given the potential risks and the lack of strong evidence supporting its use on the skin, the most prudent approach is to avoid using methylene blue for skin applications unless absolutely necessary and under close medical supervision. This recommendation prioritizes minimizing morbidity, mortality, and improving quality of life by avoiding unnecessary risks associated with methylene blue use on the skin. Always perform a small patch test before any application and discontinue use if irritation occurs, but ideally, consider alternative antiseptics that are safer and more effective for skin use 1.
From the Research
Use of Methylene Blue for Skin
- Methylene Blue (MB) is used in antimicrobial photodynamic therapy (aPDT) to treat skin infections, including those caused by bacteria, fungi, and viruses 2, 3, 4, 5, 6.
- aPDT with MB has been shown to be effective in promoting wound healing, reducing bacterial counts, and improving cosmetic results in skin infections 2, 3, 6.
- The use of MB in aPDT has been studied in various animal models, including mice and rats, and has been found to be safe and effective in treating skin infections 2, 3, 5.
- MB has been used in combination with other treatments, such as mupirocin and Nigella sativa oil, to enhance its antibacterial and antiviral activity 2, 5.
- The parameters for MB-aPDT, such as concentration, irradiation time, and light intensity, can vary depending on the specific application and the type of infection being treated 3, 4.
Mechanism of Action
- MB is a photosensitizer that, when activated by light, produces reactive oxygen species that can kill bacteria and other microorganisms 4, 6.
- The use of MB in aPDT has been shown to reduce the bacterial load in infected wounds and promote wound healing 2, 5, 6.
- MB has also been found to have antiviral activity, inhibiting the replication of certain viruses, such as the coronavirus 229E 5.
Clinical Applications
- MB-aPDT has been used to treat various types of skin infections, including those caused by Staphylococcus aureus, Pseudomonas aeruginosa, and other bacteria 2, 4, 6.
- The treatment has been found to be safe and effective, with minimal side effects and no recurrences reported in some studies 6.
- MB-aPDT may be a useful alternative to traditional antibiotic treatments, particularly in cases where antibiotic resistance is a concern 2, 3, 6.