What Is Methionyl Sh-Polypeptide-9?
Methionyl Sh-Polypeptide-9 is a lab-made peptide designed to care for hair. Scientists start with the genetic code for sh-Polypeptide-9, add a methionine code at the front then let friendly strains of E. coli read that blueprint during fermentation. The bacteria build a single chain of 166 amino acids, which is later purified and blended into cosmetic formulas. Peptides like this entered skin and hair care labs in the early 2000s when brands looked for targeted active ingredients that could mimic what the body makes on its own. Today you will spot Methionyl Sh-Polypeptide-9 in rinse-off shampoos, nourishing conditioners, leave-in sprays, hair masks and scalp serums aimed at stronger, softer strands.
Methionyl Sh-Polypeptide-9’s Cosmetic Benefits/Uses
This peptide is added to hair care products for one clear reason.
As a hair-conditioning agent it helps smooth the cuticle, improve slip, reduce breakage during combing and leave hair feeling softer and looking shinier.
Who Can Use Methionyl Sh-Polypeptide-9
This peptide is considered gentle enough for all scalp and hair types including oily, dry, combination and sensitive. It is lightweight, water soluble and non-occlusive so it will not weigh hair down or clog follicles.
Because it is made through bacterial fermentation using a fully synthetic gene sequence, no animal tissues or by-products are needed. That makes finished formulas containing Methionyl Sh-Polypeptide-9 suitable for both vegans and vegetarians as long as the rest of the ingredient list aligns with their preferences.
The molecule is large and remains on the surface of the hair shaft with minimal skin penetration. No specific warnings have been issued for pregnant or breastfeeding women, but this is not medical advice and anyone who is expecting or nursing should run new haircare products past a doctor to be on the safe side.
Methionyl Sh-Polypeptide-9 does not increase photosensitivity so it will not make the scalp or hair more prone to sun damage. It is also color safe and compatible with chemically treated or textured hair routines.
Potential Side Effects/Adverse Reactions
Side effects from topical use of Methionyl Sh-Polypeptide-9 vary from person to person. The points below outline potential reactions, though most users experience none when the ingredient is formulated and used correctly.
- Mild scalp redness or itching in very sensitive individuals
- Transient tingling sensation immediately after application
- Allergic contact dermatitis in people allergic to the peptide itself or other ingredients in the formula
- Stinging or discomfort if applied to broken or freshly irritated skin
If any of these reactions occur stop using the product and seek advice from a healthcare professional.
Comedogenic Rating
Rating: 0 (non-comedogenic)
Methionyl Sh-Polypeptide-9 is a large water-soluble peptide that stays on the hair shaft rather than sinking into pores. It contains no oily or waxy components that could block follicles so it earns the lowest possible comedogenic score.
Because of this it is considered suitable for acne-prone skin and scalps.
As with any formula the overall breakout risk depends on the full ingredient list. Heavy silicones, butters or oils paired with this peptide could raise the comedogenic profile of the final product.
Summary
Methionyl Sh-Polypeptide-9 is a lab-crafted 166-amino-acid peptide used to condition hair by smoothing the cuticle improving slip and cutting down breakage. It works by forming a thin film over each strand which helps hair feel softer and look shinier after rinsing or while left on.
You will not spot this peptide in every aisle yet it has gained steady attention among niche brands that like high-tech actives. Its vegan origin and gentle nature make it an attractive choice for clean and inclusive formulas.
Current data shows it is low risk for irritation and non-comedogenic but everyone’s skin is unique so patch testing any new product is a smart move before full use.