Overview

This is a single-center, randomized, double-blind, placebo-controlled clinical trial designed to evaluate whether topical application of Lactobacillus reuteri can safely and effectively treat androgenetic alopecia. The study is based on the concept that balancing the scalp's microbial community may support hair follicle function. Participants will be randomly assigned to one of four groups receiving either active probiotic solution, inactivated probiotic solution (control for non-viable bacterial effects), a saline placebo, or the standard treatment 5% minoxidil solution for 12 months. Neither participants nor assessing clinicians will know the assigned treatment. The main goal is to measure improvement in hair count per square centimeter after one year. Additional measures include changes in hair thickness and quality. This research seeks to provide high-quality scientific evidence on a new microbiome-targeting approach, offering future patients and healthcare providers insights into a potential alternative or complementary treatment strategy for hair loss.

Eligibility

Inclusion Criteria:

1. Patients meeting AGA diagnostic criteria (confirmed by medical history, clinical presentation, and trichoscopy) classified as Norwood-Hamilton stage II-IV or Ludwig grade I-III;
2. Provision of informed consent and voluntary participation;
3. Aged 18-60 years with generally good health status;
4. No use of any hair loss medications within the past six months;
5. Absence of alopecia areata, local infections, or neuromuscular disorders.

Exclusion Criteria:

1. AGA progression \>5 years;
2. Active skin disease (e.g., psoriasis flare) or uncontrolled diabetes/CVD;
3. Investigator-assessed protocol non-feasibility.