From the Guidelines
Methylene blue can be used topically on the skin for various conditions, but its indications are not clearly established in the provided evidence, and therefore, its use should be approached with caution and considered on a case-by-case basis, prioritizing patient safety and potential benefits. The provided evidence does not directly support the use of methylene blue for topical skin applications, as the studies primarily focus on its use in endoscopy and gastrointestinal procedures 1. However, considering the potential antimicrobial and anti-inflammatory properties of methylene blue, it may be beneficial for certain skin conditions, such as methicillin-resistant Staphylococcus aureus (MRSA) infections, fungal infections, and parasitic skin conditions. When applying methylene blue topically, it is essential to follow proper protocols, including:
- Cleaning the affected area before application
- Using a 1-2% solution
- Applying the solution directly to the affected area using a cotton swab or gauze pad
- Allowing the solution to dry completely
- Avoiding application to large open wounds or mucous membranes unless specifically directed by a healthcare provider
- Monitoring for potential side effects, such as temporary skin irritation or allergic reactions, and discontinuing use if significant irritation occurs. It is crucial to note that the evidence provided does not support the use of methylene blue for skin conditions, and its use should be guided by the most recent and highest-quality studies available. In the absence of strong evidence, a conservative approach should be taken, prioritizing patient safety and potential benefits 1.
From the Research
Indications for Topical Methylene Blue Use on the Skin
The indications for topical methylene blue (methylthioninium chloride) use on the skin include:
- Skin cancers, such as squamous cell carcinoma (SCC) 2, 3
- Acne vulgaris, due to its sebum-reducing, anti-inflammatory, and antimicrobial activities 4
- Non-melanoma skin neoplasms, as methylene blue-based photodynamic therapy has proven to be effective and promising for treatment 5
Photodynamic Therapy (PDT) Applications
Methylene blue is used as a photosensitizer in PDT for various skin conditions, including:
- Squamous cell carcinoma, where it reduces tumor size and cell proliferation, and raises cytokine levels 2
- Acne vulgaris, where it exhibits antimicrobial activity against Cutibacterium acnes and reduces sebum production 4
- Skin cancer prophylaxis, although its efficacy is limited compared to other photosensitizing agents like methyl aminolevulinate 6
Formulations and Delivery Methods
Various formulations and delivery methods are being developed to enhance the cutaneous penetration and efficacy of methylene blue, including:
- Nanoencapsulation of methylene blue for enhanced skin cancer cell phototoxicity and cutaneous penetration 3
- Sodium cholate-mediated ion-pairing for skin delivery of methylene blue, which modifies its physicochemical properties and enables partition and diffusion through the skin layers 5
- Topical nanoformulation of methylene blue and salicylic acid for the photodynamic therapy of acne vulgaris 4