Methylene blue vs methyl aminolevulinate photodynamic therapy in the treatment of mild-to-moderate toenail onychomycosis: Short- and medium-term effects

Dermatol Ther. 2020 Nov;33(6):e14280. doi: 10.1111/dth.14280. Epub 2020 Sep 15.


Photodynamic therapy (PDT) has emerged as an interesting alternative option for onychomycosis treatment. The impact of a specific photosensitizer (PS) on the final result is an important factor to consider. We conducted a short- and medium-term controlled trial to compare the effectiveness of PDT in the treatment of mild-to-moderate onychomycosis when it is mediated by two different PSs. Twenty patients were randomized to receive nine sessions of PDT distributed over 16 weeks mediated either by methylene blue (MB/PDT group) or methyl aminolevulinate (MAL/PDT group). Onychomycosis severity index (OSI) and nail involvement were checked along the study. Complete cure, treatment success, and clinical improvement were tabulated at 16 and 40-week follow-ups. OSI scores decreased significantly along the study, from 12.1 ± 5.4 to 3.6 ± 3.2 (MB/PDT group) and from 14.8 ± 6.0 to 5.4 ± 4.4 (MAL/PDT group). At 16-week follow-up, only 20% of the patients in the MB/PDT group reached complete cure and none in the group of MAL/PDT. At 40-week follow-up, complete cure rates were 70% and 40% in the MB/PDT group and MAL/PDT group respectively. Both modalities showed good outcomes in treatment of moderate toenail onychomycosis. MB/PDT showed a faster action but with relapse rates slightly higher than MAL/PDT.

Keywords: methyl aminolevulinate; methylene blue; mild-to-moderate onychomycosis; photodynamic therapy.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminolevulinic Acid / adverse effects
  • Humans
  • Methylene Blue / adverse effects
  • Nails
  • Onychomycosis* / diagnosis
  • Onychomycosis* / drug therapy
  • Photochemotherapy*
  • Photosensitizing Agents / adverse effects
  • Treatment Outcome


  • Photosensitizing Agents
  • Aminolevulinic Acid
  • Methylene Blue