Topical Application of Lactobacillus Reuteri for Androgenetic Alopecia

Safety and Efficacy of Lactobacillus Reuteri for Androgenetic Alopecia: A Single-Center, Randomized, Double-Blind, Placebo-Controlled Trial

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.

Study Overview

• Status: Recruiting
• Conditions: Androgenetic Alopecia (AGA)
• Intervention / Treatment: Biological: Lactobacillus reuteri; Biological: Inactivated Lactobacillus reuteri; Drug: 5% Minoxidil; Drug: Normal Saline

• Study Type: Interventional
• Enrollment (Estimated): 388
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Jianglin Zhang; Phone Number: +86 13873143466; Email: zhang.jianglin@szgospital.com

Study Locations

• China
  • Guangdong
    • Shenzhen, Guangdong, China
      • Recruiting
      • ShenZhen People's Hospital
      • Contact: Shenzhen People's Hospital; Phone Number: +86 75522943881; Email: 195323995@qq.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Test Group; Daily application of 1 sachet containing Lactobacillus reuteri powder (≈10^9 CFU) dissolved in 1 mL normal saline within a brown glass vial. After thorough mixing, 1 mL of the probiotic solution was topically applied to the scalp using cotton swabs following scalp cleansing. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.	Biological: Lactobacillus reuteri; Daily application of 1 sachet containing Lactobacillus reuteri powder (≈10^9 CFU) dissolved in 1 mL normal saline within a brown glass vial. After thorough mixing, 1 mL of the probiotic solution was topically applied to the scalp using cotton swabs following scalp cleansing. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.
Other: Inactivated Control Group; Daily application of 1 sachet containing inactivated Lactobacillus reuteri powder (≈10^9 CFU pre-inactivation) dissolved in 1 mL normal saline within a brown glass vial. After thorough mixing, 1 mL of the solution was topically applied to the scalp using cotton swabs following scalp cleansing. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.	Biological: Inactivated Lactobacillus reuteri; Daily application of 1 sachet containing inactivated Lactobacillus reuteri powder (≈10^9 CFU pre-inactivation) dissolved in 1 mL normal saline within a brown glass vial. After thorough mixing, 1 mL of the solution was topically applied to the scalp using cotton swabs following scalp cleansing. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.
Active Comparator: Positive Control Group; Commercially available 5% minoxidil tincture was aliquoted into brown glass vials (1 mL/vial). Following daily scalp cleansing, 1 mL solution was topically applied to the scalp. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.	Drug: 5% Minoxidil; Commercially available 5% minoxidil was aliquoted into brown glass vials (1 mL/vial). Following daily scalp cleansing, 1 mL solution was topically applied to the scalp. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.
Placebo Comparator: Negative Control Group; Normal saline was aliquoted into brown glass vials (1 mL/vial). Following daily scalp cleansing, 1 mL solution was topically applied to the scalp using cotton swabs. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.	Drug: Normal Saline; Normal saline was aliquoted into brown glass vials (1 mL/vial). Following daily scalp cleansing, 1 mL solution was topically applied to the scalp using cotton swabs. Participants refrained from hair washing for ≥6 hours post-application. Applied once daily for 12 months.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hair Density	Hair density is quantified by counting all visible growing hairs in a unit area of the scalp using a trichoscope	The follow-up periods are set at 1, 3, 6, and 12 months after the initial treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hair Diameter	Trichoscopy is used to measure the average hair shaft diameter (cross-sectional thickness) of all growing hairs in a defined scalp area.	The follow-up periods are set at 1, 3, 6, and 12 months after the initial treatment

Collaborators and Investigators

• Sponsor: Shenzhen People's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): January 25, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: January 17, 2026
• First Submitted That Met QC Criteria: January 17, 2026
• First Posted (Actual): January 27, 2026

Study Record Updates

• Last Update Posted (Actual): April 1, 2026
• Last Update Submitted That Met QC Criteria: March 31, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Androgenetic Alopecia; Lactobacillus reuteri
• Additional Relevant MeSH Terms: Pathological Conditions, Anatomical; Skin Diseases; Hypotrichosis; Hair Diseases; Pathological Conditions, Signs and Symptoms; Skin and Connective Tissue Diseases; Alopecia; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Pharmaceutical Preparations; Piperidines; Pyrimidines; Crystalloid Solutions; Isotonic Solutions; Solutions; Minoxidil; Saline Solution
• Other Study ID Numbers: LL-KY-2025109-02

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No