Injecting vitamin D directly into warts cleared 40% of them completely and significantly boosted the antimicrobial peptide LL-37, revealing how the treatment activates the skin's natural viral defense.
40% complete wart clearanceVitamin D injections significantly increased LL-37 expression in wart tissue (p=0.003), with the highest LL-37 levels in patients whose warts cleared completely.
What the researchers found
Injecting vitamin D directly into common warts (verruca vulgaris) significantly increased expression of the antimicrobial peptide LL-37 (cathelicidin) in the skin (p=0.003). Of 20 patients treated, 40% showed complete wart clearance and 35% showed partial response. Warts that cleared completely had the highest LL-37 expression (p=0.022).
After treatment, the skin also showed decreased epidermal thickness and reduced inflammatory cell density, indicating the immune response was shifting from chronic inflammation toward effective viral clearance driven by LL-37.
Why it matters
LL-37 is the body's primary antimicrobial peptide and plays a key role in fighting viral infections in the skin. This study provides a mechanistic explanation for why vitamin D injections work against warts — they boost the skin's natural LL-37 production, helping the immune system recognize and clear the HPV virus. This connects two major research areas: vitamin D's role in immunity and cathelicidin's antiviral properties.
The numbers in context
n=20 patients · 10 healthy controls · 40% complete response · 35% partial response · 25% no response · LL-37 increase p=0.003 · Complete responders p=0.022 · Max 4 sessions every 2 weeks
How the study worked
Twenty patients with multiple common warts received intralesional vitamin D3 injections every 2 weeks for up to 4 sessions or until warts cleared. Skin biopsies were taken before and after treatment and compared to samples from 10 healthy controls. LL-37 expression was assessed by immunohistochemistry. Histopathological changes in the epidermis and dermis were also evaluated.
Who was studied
20 patients with multiple common warts (verruca vulgaris) and 10 healthy age/sex-matched controls
What this study cannot tell us
Small sample size (20 patients) limits generalizability. No placebo or sham injection control group — response could partly be due to the injection itself triggering local immunity. The study was not blinded. No long-term follow-up to assess recurrence rates.
How to read the evidence
This is a small interventional study with 20 patients and no control group receiving sham injections. While the immunohistochemical evidence linking vitamin D to LL-37 upregulation is compelling, the lack of blinding and small sample limit the strength of the clinical efficacy findings.
When this study was published
Published in 2022. The connection between vitamin D and cathelicidin expression remains an active research area, and intralesional vitamin D for warts continues to be studied.
The bigger picture
LL-37 is increasingly recognized as a frontline defender in skin immunity, with roles in fighting bacteria, viruses, and fungi. This study adds wart clearance to LL-37's growing resume and demonstrates that its expression can be deliberately upregulated through vitamin D — a finding with implications for other skin infections and conditions where cathelicidin deficiency plays a role.
Questions still open
- Could topical or oral vitamin D supplementation boost LL-37 enough to prevent wart recurrence?
- Would patients with low baseline vitamin D levels show even greater responses to intralesional injection?
- Could this LL-37-boosting mechanism be exploited for other HPV-driven conditions like genital warts or cervical dysplasia?
Common questions
How does vitamin D help clear warts?
What is LL-37 and why does it matter for skin infections?
Read the original research
Intralesional injection of vitamin D in verruca vulgaris increases cathelicidin (LL37) expression; therapeutic and immunohistochemical study.
The Journal of dermatological treatment, 33(1), 291-296
Citation
Sorour, Neveen E; Elesawy, Fatma M; Abdou, Asmaa G; Abdelazeem, Sara E; Akl, Essam M. (2022). Intralesional injection of vitamin D in verruca vulgaris increases cathelicidin (LL37) expression; therapeutic and immunohistochemical study.. The Journal of dermatological treatment, 33(1), 291-296. https://doi.org/10.1080/09546634.2020.1750554