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Hair prebiotics and probiotics: what microbiome science is changing
Prebiotics, probiotics and postbiotics: discover how the science of the hair microbiome is transforming hair and scalp care.
Prebiotics, probiotics and postbiotics for hair: understanding the scalp microbiome
Hair prebiotics extend a logic already well known in skincare to the hair: supporting the skin ecosystem rather than trying to strip it. Comfortable hair depends notably on a balanced scalp, where bacteria and yeast coexist without a single microorganism explaining all disorders on its own.
This page sorts through prebiotics, probiotics and postbiotics, explains what cosmetic prebiotics research covers, and shows how to integrate them into a microbiome-friendly routine without a promise of miracle regrowth.
Does your hair microbiome seem unbalanced?
Indicative self-assessment, not a medical diagnosis. Simply count the number of situations that describe you.
- The scalp microbiome refers to the set of microorganisms naturally present on the surface of the scalp.
- Prebiotics feed beneficial microorganisms; probiotics and postbiotics belong to the world of microbiome actives.
- The Night Serum is the treatment most directly concerned by probiotics/postbiotics: scalp and roots only.
- The Scrub is an occasional reset: every 10 to 15 days, it replaces shampoo that day.
Madame d’Alexis treatments concerned by the microbiome
The products highlighted are those that have a real link with the scalp: The Night Serum for the roots, The Shampoo for gentle washing, The Scrub for the occasional reset.
The Night Serum for roots
- Scalp and roots only
- In the evening, section by section
- A few drops, leave-in
The gentle Shampoo
- Without sulfates or silicones
- pH 5, gentle washing
- Cationic hyaluronic acid
The reset Scrub
- Every 10 to 15 days
- Replaces shampoo that day
- For sebum, pollution or residues
Which prebiotic shampoo to choose?
A prebiotic shampoo remains first a rinse product: its cleansing base, its tolerance and the stability of the active count as much as the presence of the word "prebiotic" on the label. A prebiotic feeds microorganisms already present; it does not necessarily add live bacteria to the scalp.
In a shampoo, the logic is therefore mainly to clean without over-stripping while integrating an active compatible with a rinse formula. The Madame d’Alexis Shampoo belongs to this approach with its prebiotics, its organic hydrolats, its cationic hyaluronic acid and its plant-based keratin. When the roots saturate after sports, helmet or heat, see also our guide on sweating and scalp buildup.
The scalp microbiome: a still unknown ecosystem
The scalp is colonized by bacteria and yeast that coexist naturally. We speak of the hair microbiome to designate this invisible balance. When it works correctly, it supports the comfort of the scalp, the hydrolipidic film and the tolerance to treatments.
An imbalance can be associated with dandruff, an excess of sebum or scalp itching, but it should not be reduced to a single cause. In case of patches, pain, scabs, unusual hair loss or persistent symptoms, a dermatological opinion remains necessary.
Cutibacterium
Bacterial family naturally present on the skin and scalp.
Staphylococcus
Group present in the skin ecosystem, whose balance depends on the terrain.
Malassezia
Naturally present yeast, often mentioned in dandruff issues when it proliferates.
Prebiotics, probiotics, postbiotics: what differences?
These three families are often confused. Yet they do not play the same role in a hair routine.
Let's start with the term most often misused. A prebiotic is neither a bacterium nor a living microorganism: in the scientific sense, it is a substrate used selectively by host microorganisms and associated with a benefit. Applied as a treatment, a scalp prebiotic therefore aims to feed the already present flora rather than "colonize" the skin. This logic of topical modulation of the skin microbiota is still an active research area; clinical data remain more developed for certain dermatological applications than for haircare. Source: Microbiote Institute ↗
| Family | Simple definition | Cosmetic role | Madame d’Alexis product concerned |
|---|---|---|---|
| Prebiotics | Substrates that feed the already present beneficial microorganisms. | Help maintain a more balanced terrain. | The Shampoo. |
| Probiotics | Actives associated with the microbiome world. | Support the balance of the scalp. | The Night Serum. |
| Postbiotics | Fermentation-derived compounds, more stable than living microorganisms. | Contribute to comfort and the skin barrier. | The Night Serum. |
Madame d’Alexis microbiome-friendly routine
The objective is simple: respect the scalp like skin. We avoid aggressive washing, limit the accumulation of residues and choose targeted treatments according to the real need of the scalp.
Wash gently
The Shampoo cleanses the scalp without sulfates or silicones. Its formula combines organic hydrolats, cationic hyaluronic acid, prebiotics and plant-based keratin to keep a comfortable routine. To understand the botanical base of the formulas, consult our guide on hydrolats for hair.
Target the roots in the evening
The Night Serum is applied section by section, on the scalp and roots. A few drops are enough to integrate probiotics and postbiotics into a light nighttime routine.
Reset when the roots saturate
In case of sebum, pollution, sweating or styling product residues, The Scrub offers an occasional reset gesture every 10 to 15 days. That day, it takes the place of shampoo. Our guide on hair scrub before or after shampoo explains why this gesture is sufficient on its own in the routine.
Stabilize the routine
The microbiome appreciates regularity: lukewarm water, long rinsing, few occlusive products on roots and measured repeated gestures rather than an accumulation of treatments.
Which active to favor according to your profile?
| Profile | Main problem | Recommended routine | Business or informative page to push |
|---|---|---|---|
| Sensitive scalp | Tingling, discomfort, tightness. | The gentle Shampoo + Night Serum if needed, without scrub if active irritation. | shampoo for itchy scalp. |
| Light dandruff | Flakes, occasional itching. | Gentle routine, occasional Scrub if buildup, medical opinion if persistent. | dandruff dry scalp. |
| Oily scalp | Heavy roots, quick sebum. | The Shampoo, Scrub every 10 to 15 days if saturation. | oily hair after shampoo. |
| Weakened roots | Sensation of reduced density or diffuse hair loss. | Night Serum in root routine, consultation if unusual hair loss. | probiotic serum for scalp. |
| Product buildup | Heavy roots, dull hair, feeling of suffocation. | Occasional reset with The Scrub. | scalp scrub. |
The gestures that disrupt the scalp microbiome
- Wash too often with a stripping shampoo.
- Use very hot water, especially on sensitive scalp.
- Accumulate dry shampoo, styling sprays and oils on roots without occasional reset.
- Do a scrub too often: the good Madame d’Alexis rhythm remains every 10 to 15 days.
- Apply The Night Serum on the lengths instead of the scalp and roots.
- Attribute a major hair loss only to the microbiome without professional opinion.
3 markers to read a microbiome formula without being fooled by marketing
Prebiotic ≠ probiotic
A prebiotic feeds an existing microbial ecosystem. A probiotic, in the strict scientific sense, designates a living microorganism bringing a benefit. In cosmetics, we also find ferments, lysates and postbiotics: it is therefore necessary to read the formula rather than the only marketing name.
In a rinse formula, everything counts
For a prebiotic shampoo, the gentleness of the cleansing base, the contact time, the stability and the overall coherence of the formula count as much as the presence of a prebiotic active.
Microbiome ≠ regrowth promise
A comfortable scalp constitutes a more favorable cosmetic terrain, but a microbiome treatment should not be presented as a treatment of alopecia. A sudden, localized or persistent hair loss deserves a dermatological opinion.
FAQ - Prebiotics, Probiotics and the Hair Microbiome
What is the difference between prebiotics and probiotics for hair?
Prebiotics serve as a substrate for microorganisms already present. Probiotics refer, in the strictest scientific sense, to live microorganisms that provide a benefit; in cosmetics, ferments, lysates and postbiotics are also found. In the Madame d’Alexis range, Le Shampoing contains prebiotics and Le Sérum Nuit features the probiotic/postbiotic universe.
Does Madame d’Alexis Le Shampoing contain probiotics?
No. Le Shampoing contains organic hydrosols, cationic hyaluronic acid, prebiotics and plant-based keratin. Probiotics/postbiotics are found in Le Sérum Nuit.
Is Le Sérum Nuit applied to the lengths?
No. Le Sérum Nuit is applied to the scalp and roots in the evening, section by section, and then left on without rinsing. It does not replace a finishing serum intended for the lengths.
Do prebiotics make hair grow?
Guaranteed growth should not be promised. Prebiotics can be part of a microbiome care routine, but growth depends on many factors: genetics, hormones, nutritional status, the hair cycle and scalp health.
When should Le Scrub be used in a microbiome routine?
As an occasional reset when the scalp is burdened with sebum, pollution or residue. The Madame d’Alexis routine is every 10 to 15 days and Le Scrub replaces shampoo on that day. Avoid it on a scalp experiencing active irritation.
What is a prebiotic in a cosmetic product?
In a cosmetic product, a prebiotic is an ingredient chosen to be selectively used by certain host microorganisms. The ISAPP reference definition refers to a substrate selectively used by host microorganisms and conferring a benefit. Therefore, not all sugars, fibers or plant extracts are automatically prebiotics. See the ISAPP definition.
Can prebiotics help in cases of hair loss?
Prebiotics are not a treatment for androgenetic alopecia and should not be presented as a regrowth active. Their benefit lies in supporting the scalp. The usage result of an 89% reduction in hair loss observed at 60 days concerns Le Sérum Nuit, which combines probiotics/postbiotics and botanical actives, not Le Shampoing with prebiotics. In case of sudden, diffuse or localized hair loss, consult a dermatologist.
Useful Sources
ISAPP - definition and criteria of prebiotics: a prebiotic is a substrate selectively used by host microorganisms and associated with a benefit.
Biocodex Microbiota Institute - topical modulation of the skin microbiome: topical approaches are being studied, although evidence remains limited depending on the indications.
Yin et al. (2024), systematic review on probiotics, hair growth and dandruff, PMC/NIH.
Moosbrugger-Martinz et al. (2024), work on the scalp microbiome and postbiotic formulation, Scientific Reports.
Madame d’Alexis documentation: Shampoo with prebiotics, Night Serum with probiotics/postbiotics, Scrub as an occasional scalp reset.
