Amp-Isostearoyl Hydrolyzed Keratin: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 23, 2025
Share:
Inside this article:

We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Amp-Isostearoyl Hydrolyzed Keratin?

Amp-Isostearoyl Hydrolyzed Keratin is a specialty form of keratin that has been broken down into small peptides, reacted with isostearic acid, then neutralized with aminomethyl propanol to form a salt. The keratin itself usually comes from renewable animal sources such as wool or feathers. By coupling these tiny keratin fragments with a fatty acid, chemists create a molecule that clings well to skin and hair and mixes easily with water and oils.

Hydrolyzed keratin has been used in beauty care since the 1970s for its ability to reinforce damaged hair. Over time formulators looked for ways to boost its conditioning power and stability. The isostearoyl modification solved both issues, giving the ingredient a soft feel and better rinse resistance. Today manufacturers produce it by first hydrolyzing raw keratin with enzymes or gentle acid, filtering the peptides, reacting them with isostearic acid chloride, then adjusting the pH with aminomethyl propanol. The final powder or liquid is easy to add during the cool-down phase of most formulations.

You will see Amp-Isostearoyl Hydrolyzed Keratin in rinse-off and leave-on hair products like shampoos, conditioners, masks, serums, styling creams and color-protect sprays. It also shows up in skin care such as body washes, hand creams, facial moisturizers and soothing after-sun lotions where a light protective film is desired.

Amp-Isostearoyl Hydrolyzed Keratin’s Cosmetic Benefits/Uses

This multi-tasking ingredient supports several performance goals in modern formulas:

  • Cleansing: The fatty portion helps lift away surface oils and impurities while the keratin peptides keep the process gentle so hair and skin do not feel stripped
  • Hair conditioning: The positively charged peptides bond to damaged areas along the cuticle, boosting softness, strength and shine even after rinsing
  • Skin conditioning: Forms a breathable film that smooths rough patches, reduces moisture loss and leaves a silky finish without heaviness

Who Can Use Amp-Isostearoyl Hydrolyzed Keratin

This ingredient is considered friendly for most skin types, from dry to oily and even sensitive, because it forms a lightweight film that helps hold moisture without clogging pores or leaving a greasy feel. Extremely acne-prone skin may wish to monitor for buildup, yet the risk is low due to the small peptide size and balanced fatty portion.

Amp-Isostearoyl Hydrolyzed Keratin is not suitable for strict vegans or vegetarians because the source keratin is typically derived from animal materials such as wool or feathers. Anyone avoiding animal-derived ingredients should look for plant-based protein alternatives instead.

No specific warnings exist for pregnant or breastfeeding women when this ingredient is used topically in cosmetic amounts. Still, this is not medical advice and anyone who is expecting or nursing should show the full ingredient list of any product to a healthcare professional before use.

The ingredient does not increase photosensitivity, so it will not make skin more likely to burn in the sun. It is compatible with common actives such as vitamin C, niacinamide and retinoids, and it performs well in both rinse-off and leave-on formulas.

Potential Side Effects/Adverse Reactions

Side effects and reactions to the topical application of Amp-Isostearoyl Hydrolyzed Keratin can vary from person to person. The points below outline potential issues only; most users will not experience any of them when the ingredient is properly formulated in a product.

  • Mild skin redness or itching, especially on very sensitive skin
  • Contact dermatitis in individuals allergic to wool, feathers or other keratin sources
  • Scalp or hair buildup if used in high concentrations without adequate rinsing
  • Eye irritation if the product accidentally gets into the eyes during application

If any discomfort, rash or other negative reaction occurs, discontinue use and seek advice from a medical professional.

Comedogenic Rating

Rating: 1 / 5
Amp-Isostearoyl Hydrolyzed Keratin is mostly made up of small water-loving peptides that rinse clean, paired with a lightweight branched fatty acid that spreads thinly on skin. This blend does not readily settle into pores or create the dense oily film that typically triggers clogged pores, so the overall clogging potential is very low. It should be fine for people who are prone to acne or breakouts, especially when used in rinse-off products like shampoos and body washes. Formulas that stay on the skin may carry a slightly higher risk if they also contain heavier oils, but the ingredient itself remains low risk.

As always, the final product formula and how often it is layered can influence pore-clogging potential more than any single ingredient.

Summary

Amp-Isostearoyl Hydrolyzed Keratin acts as a gentle cleanser, a hair strengthener and a skin-softening film former. The keratin peptides bond to damaged hair and rough skin while the isostearic acid portion lifts away grime and gives a silky after-feel. Its dual water-and-oil affinity lets it condition without greasiness and helps active ingredients spread more evenly.

The ingredient is a quiet workhorse rather than a headline maker. It is popular in professional salon lines and mid-tier skin care yet you will not see it hyped on every label like hyaluronic acid or niacinamide.

Safety data and years of use show it is well tolerated for most people with only rare cases of sensitivity linked to wool or feather allergies. While it scores low for comedogenicity and has no known reproductive or photo-toxic issues, it is always smart to patch test a new product to make sure it suits your unique skin and scalp.

Was this article helpful?
More from Glooshi:
ADVERTISEMENT
Get all our top headlines in beauty.
Delivered right to your inbox each week. Zero spam, all goodness, opt-out at anytime.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Send good feedback:

All feedback is greatly appreciated, anonymous, and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Send bad feedback:

All feedback is greatly appreciated, anonymous, and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.