Hair loss linked to gut and scalp bacteria in new study

NCT ID NCT07716748

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First seen Jul 21, 2026 · Last updated Jul 22, 2026 · Updated 1 time

Summary

This study investigates whether the bacteria living in the gut and on the scalp differ between men with androgenetic alopecia (common hair loss) and those without. Researchers will also look at how these bacterial communities change after treatment with oral minoxidil, a standard hair-loss medication. By analyzing stool, scalp swabs, hair follicles, and blood samples, the study aims to uncover biological markers that could lead to better understanding and future treatments for hair loss.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
oral minoxidil
What this could lead to
If successful, this could reveal how gut and scalp bacteria influence hair loss and point toward new microbiome-based treatments.
What could go wrong
This is an early exploratory study with only 66 participants, so findings may not apply broadly. It focuses on biological markers, not on proving that minoxidil works.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Participants

About 66 people

The number the study aims to enrol. It can still change while the study runs.

Expected to start

Aug 2026

An estimate. Start dates often move.

Expected to finish

Jan 2028

An estimate. End dates often move.

Lead sponsor

A research network

The lead sponsor is a research network or cooperative group.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Who is studied

AGA volunteers will be referred by clinicians from National Skin Centre Healthy volunteers will be recruited by recruitment posters at National Skin Centre

Ages

21 to 45 years

Sex

Male participants only

Healthy volunteers

Accepted

You do not need to have the condition being studied to take part.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Male volunteer from 21 to 45 years old 2. Volunteer with BMI between 18.5 to 30 kg/m2 3. Volunteer willing and able to fulfill the study requirements and schedule 4. Volunteer willing to give their stool sample, as well as swabs, follicles, and blood. 5. Volunteer informed about the study objectives and procedures, and able to understand them 6. Volunteer who has given written informed consent Volunteers in the healthy control panel must satisfy the following criteria: 1. Volunteer in overall good health 2. Volunteer with no diagnosis of hair loss or other condition or treatment susceptible to impact hair count and microbiome. Volunteers in the AGA panel must satisfy the following criteria: 1. Volunteer diagnosed with Androgenetic Alopecia grade III Vertex to V on the Hamilton-Norwood scale 2. Volunteer willing to restrain from the use of any additional hair loss oral and topical pharmaceuticals (ex: topical minoxidil) over the course of the study 3. Volunteer eligible to undergo oral minoxidil treatment, with no contra-indication Exclusion Criteria: 1. Volunteer with severe gastro-intestinal symptoms (including gluten and lactose intolerance) 2. Volunteer with auto-immune disease, diabetes; hyper or hypo-thyroidism ; chronic kidney failure 3. Volunteer with diagnosis of scalp-related disease such as folliculitis, lichen planopilaris, folliculitis decalvans, tinea capitis, head lice, or seborrheic dermatitis 4. Volunteer undergoing hypertension treatment 5. Volunteer who undertook any oral anti-hair loss pharmaceutical treatment in the past 3 months (e.g. Finasteride) 6. Volunteer who undertakes any hormone-disrupting drug 7. Volunteer who used topical minoxidil or other pharmaceutical-grade topical hair restorers in the past 3 months 8. Volunteer with a total dandruff score above 1 on the L'Oreal Dandruff scale. 9. Volunteer who used perms or hair dyes in the past 2 months 10. Volunteer who underwent scalp reduction or hair transplant procedures 11. Volunteer who declares to be deprived of freedom by administrative or legal decision 12. Volunteer who cannot be contacted by phone in case of emergency 13. Volunteer having currently participating in another clinical study 14. Volunteer who used antibiotics or antifungal medication (topical to scalp and systemic) in the past 4 weeks 15. Volunteer who used probiotics supplements in the past 4 weeks. (dietary probiotics such as yogurt, kefir, and kimchi are acceptable) 16. Volunteer who follows a non-conventional diet (e.g. vegan, ketogenic, strict intermittent fasting diets) Non-inclusion Criteria: 1. Volunteer diagnosed with HIV, Hepatitis C, Hepatitis B 2. Volunteer with severe gastro-intestinal symptoms (including gluten and lactose intolerance) 3. Volunteer with auto-immune disease, diabetes; hyper or hypo-thyroidism ; chronic kidney failure 4. Volunteer with diagnosis of scalp-related disease such as folliculitis, lichen planopilaris, folliculitis decalvans, tinea capitis, head lice, or seborrheic dermatitis 5. Volunteer undergoing hypertension treatment 6. Volunteer who undertook any oral anti-hair loss pharmaceutical treatment in the past 3 months (e.g. Finasteride) 7. Volunteer who undertakes any hormone-disrupting drug 8. Volunteer who used topical minoxidil or other pharmaceutical-grade topical hair restorers in the past 3 months 9. Volunteer with a total dandruff score above 1 on the L'Oreal Dandruff scale. 10. Volunteer who used perms or hair dyes in the past 2 months 11. Volunteer who underwent scalp reduction or hair transplant procedures 12. Volunteer who declares to be deprived of freedom by administrative or legal decision 13. Volunteer who cannot be contacted by phone in case of emergency 14. Volunteer having currently participating in another clinical study 15. Volunteer who used antibiotics or antifungal medication (topical to scalp and systemic) in the past 4 weeks 16. Volunteer who used probiotics supplements in the past 4 weeks. (dietary probiotics such as yogurt, kefir, and kimchi are acceptable) 17. Volunteer who follows a non-conventional diet (e.g. vegan, ketogenic, strict intermittent fasting diets) 18. Volunteer who used anti-dandruff shampoo in the past 4 weeks (For example, commonly used brands for anti-dandruffs could be : Head \& Shoulders, Sebamed, Clear, Dove, Pantene, L'OREAL, Vichy Dercos)

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Conditions

The condition(s) this trial relates to.

As listed by the trial registrant

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