Comparative Retrospective Evaluation of the Clinical and Mycological Efficacy of 69% Nitric Acid, 1064 nm Nd:YAG Laser, and Their Combination in the Treatment of Trichophyton rubrum Onychomycosis over a 12-Month Follow-Up

<b>Background</b>: Onychomycosis is a common nail infection primarily caused by <i>Trichophyton rubrum</i>, posing therapeutic challenges due to poor antifungal penetration and high recurrence rates. Conventional treatments include topical and systemic antifungals, but novel approaches such as laser therapy and chemical agents like nitric acid have emerged as promising alternatives or adjuncts. However, comparative evidence regarding the clinical and mycological efficacy of these treatments remains limited. <b>Objectives</b>: We aimed to assess and compare the clinical and mycological efficacy of three therapeutic modalities-69% nitric acid, 1064 nm Nd:YAG laser, and their combination-in the treatment of <i>Trichophyton rubrum</i> onychomycosis over a 12-month follow-up period. <b>Methods</b>: A prospective, comparative, observational study was conducted, assigning patients with confirmed onychomycosis to one of three treatment groups: nitric acid, Nd:YAG 1064 nm laser, or combination therapy. Clinical and mycological cure rates, mean time to clinical resolution, changes in Onychomycosis Severity Index [OSI] scores, and mycological relapse rates were assessed over a 12-month follow-up. <b>Results</b>: All three groups demonstrated significant improvement in both clinical and mycological cure rates, with the combination therapy yielding the most favorable outcomes in terms of response speed and durability. Laser and nitric acid monotherapies were also effective, though associated with lower cure rates and longer times to resolution. The relapse rate was lowest in the combination group. <b>Conclusions</b>: The combination of nitric acid and Nd:YAG laser appears to be a more effective therapeutic option for <i>Trichophyton rubrum</i> onychomycosis, offering superior clinical and mycological outcomes compared to monotherapies, with faster resolution and lower relapse rates. These findings suggest that combination therapy may optimize the management of this challenging nail infection.