What Is Oligopeptide-91 Sh-Polypeptide-2?
Oligopeptide-91 Sh-Polypeptide-2 is a lab-designed fusion peptide created by combining the genetic blueprints of two smaller peptides, Oligopeptide-91 and Sh-Polypeptide-2. Scientists insert the blended gene into harmless strains of E. coli, let the bacteria ferment, then harvest and purify the resulting peptide. The finished ingredient is a single chain made of 126 amino acids that may form sturdy disulfide bonds or light sugar links, helping it stay stable once mixed into a cosmetic formula.
This peptide first caught attention in the early 2000s when formulators started looking for targeted hair care actives that could offer conditioning without heavy oils or silicones. Its predictable structure, consistent quality, and cruelty-free production quickly made it a favorite among brands focused on high-performance yet gentle formulas.
You will most often see Oligopeptide-91 Sh-Polypeptide-2 listed on the labels of rinse-out or leave-in conditioners, hair masks, strengthening serums, and multi-benefit shampoos. Some scalp serums and edge-taming creams also use it to boost softness and manageability.
Oligopeptide-91 Sh-Polypeptide-2’s Cosmetic Benefits/Uses
This peptide is prized for a single but important role in hair care.
As a hair conditioning agent Oligopeptide-91 Sh-Polypeptide-2 helps smooth the hair cuticle, reduce friction during brushing, and improve overall softness. Because the molecule is small it can settle into damaged spots along the hair shaft, giving strands a healthier feel without weighing them down. Users often notice easier detangling, less breakage, and a light glossy finish.
Who Can Use Oligopeptide-91 Sh-Polypeptide-2
Because it is a lightweight peptide and not an oil or silicone, Oligopeptide-91 Sh-Polypeptide-2 is generally well tolerated by all scalp and hair types including oily, dry, sensitive and combination. It is water based and free of common pore cloggers so it rarely aggravates breakouts along the hairline. Those with extremely reactive or allergy-prone skin should still stay alert to any new sensations after use since any protein can occasionally trigger sensitivity.
The ingredient is produced through bacterial fermentation without animal-derived materials, making it suitable for both vegans and vegetarians. Brands that hold third-party vegan certifications usually highlight this on their packaging.
No specific warnings exist for pregnant or breastfeeding women. The molecule is too large to penetrate deeply into skin and is used externally on hair strands, not the bloodstream. Still, this is not medical advice and anyone who is pregnant or nursing should review all personal care products with a qualified healthcare provider just to be safe.
Oligopeptide-91 Sh-Polypeptide-2 does not cause photosensitivity, so it will not increase the risk of sunburn or require special daytime precautions. It also plays nicely with most other common hair care actives and styling ingredients.
Potential Side Effects/Adverse Reactions
Side effects and reactions to topical Oligopeptide-91 Sh-Polypeptide-2 can differ from person to person. The points below outline potential issues, though most users will not experience them when the ingredient is correctly formulated and applied.
- Mild scalp irritation – tingling or slight burning that subsides after rinsing
- Allergic contact dermatitis – redness, swelling or rash in those with a specific peptide allergy
- Itching or flaking – usually tied to an individual intolerance or overuse of a highly concentrated product
- Watery eyes or nasal irritation – rare aerosol sensitivity if the peptide is delivered in a spray mist
- Protein overload on hair – very infrequent softness loss or brittleness when layered with multiple protein rich products
If any negative reaction occurs stop using the product immediately and seek guidance from a medical professional or licensed dermatologist.
Comedogenic Rating
Rating: 0
Oligopeptide-91 Sh-Polypeptide-2 is a water-soluble peptide with no oils, waxes or fatty acids that could block pores. It sits on the hair shaft rather than the skin surface and is rinsed or lightly left on, so the risk of buildup inside follicles is minimal. Because of its large molecular size and clean, non-greasy profile, the likelihood of it triggering blackheads or whiteheads is extremely low.
Suitable for acne-prone and breakout-prone users.
Extra note: any product can still cause trouble if it is formulated with other heavy ingredients, so always look at the full label when shopping for a truly non-comedogenic routine.
Summary
Oligopeptide-91 Sh-Polypeptide-2 is a lab-crafted 126-amino-acid peptide designed to condition hair. It smooths the cuticle, fills in weak spots along the strand and reduces friction to leave hair softer, glossier and easier to detangle without weight.
While not yet a household name it is quietly gaining ground in boutique conditioners, leave-ins and masks that aim for lightweight strength and a vegan claim.
Safety profiles show it is generally gentle with low irritation and zero comedogenicity, though rare allergies can occur. As with any new cosmetic it is wise to patch test first to confirm personal tolerance before full use.