Ingredient review

AMP-Isostearoyl Hydrolyzed Silk

INCI: AMP-ISOSTEAROYL HYDROLYZED SILK

A gentle, silk-derived ingredient that smooths hair and softens skin without heavy buildup.

beautyskincarehaircare

In plain English

This ingredient is made from silk proteins that have been modified to stick to hair and skin better. It helps reduce frizz, adds shine, and makes hair feel silky without weighing it down. On skin, it leaves a soft, smooth feel without being greasy.

Quick decision guide

Useful, but context matters

AMP-Isostearoyl Hydrolyzed Silk is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging AMP-Isostearoyl Hydrolyzed Silk.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

A modified silk protein created by attaching isostearic acid (a fatty acid) to hydrolyzed silk via an AMP (aminomethyl propanol) salt. This makes it more substantive and conditioning than plain silk protein.

How it works

The fatty acid portion helps the ingredient cling to the surface of hair or skin, forming a thin, flexible film. This film smooths the cuticle (the outer layer of hair) or skin surface, reducing friction and static, and locking in moisture.

Pros

Lightweight conditioning

Unlike heavy oils or silicones, this ingredient provides smoothness and shine without making hair feel greasy or limp.

Gentle on skin

It has a low irritation and comedogenic risk, making it suitable for most skin types, including sensitive skin.

Cons and cautions

Variable performance

Its conditioning effect depends on the product's pH and the presence of other ingredients, so results may vary between formulations.

Not for all hair types

On very fine or low-porosity hair, too much can cause slight buildup over time, though less than many other conditioners.

Best for

  • Anyone with dry, frizzy, or damaged hair looking for a lightweight smoothing agent
  • People who want a non-greasy skin softener

Use caution if

  • Those with a known allergy to silk proteins (rare)

Usage tips

Look for it in leave-in conditioners or serums for best frizz control.
Pair with a gentle shampoo to avoid buildup if used daily.

Safety summary

AMP-Isostearoyl Hydrolyzed Silk is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, and no significant safety concerns have been reported in regulatory reviews.

Research notes

Studies on hydrolyzed silk and its derivatives show they improve hair smoothness and reduce breakage. The specific AMP-isostearoyl modification enhances substantivity, but direct clinical trials on this exact ingredient are limited.

Common label clues

Typical concentration
0.1% to 2%
Regulatory status
Approved for cosmetic use in the EU, US, and other major markets with no known restrictions.
Common uses
Shampoos, Conditioners, Hair masks, Leave-in treatments, Serums, Moisturizers
Environmental note
Silk production has a moderate environmental footprint; however, this derivative uses small amounts and is biodegradable.

Good to know

  • This ingredient is vegan-friendly since it's derived from silk, but check the source if you avoid animal-derived ingredients.
  • It is often listed near the middle or end of an ingredient list, indicating a moderate to low concentration.

Common questions

What is AMP-Isostearoyl Hydrolyzed Silk in beauty products?

This ingredient is made from silk proteins that have been modified to stick to hair and skin better. It helps reduce frizz, adds shine, and makes hair feel silky without weighing it down. On skin, it leaves a soft, smooth feel without being greasy.

What does AMP-Isostearoyl Hydrolyzed Silk do in a beauty product?

The fatty acid portion helps the ingredient cling to the surface of hair or skin, forming a thin, flexible film. This film smooths the cuticle (the outer layer of hair) or skin surface, reducing friction and static, and locking in moisture.

Is AMP-Isostearoyl Hydrolyzed Silk safe for most people?

AMP-Isostearoyl Hydrolyzed Silk is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, and no significant safety concerns have been reported in regulatory reviews.

Who should be careful with AMP-Isostearoyl Hydrolyzed Silk?

Those with a known allergy to silk proteins (rare)

Research sources

Cosmetic Ingredient Review (CIR) - Hydrolyzed Silk SafetyOpenPubMed - Silk proteins in hair careOpenINCI Decoder - AMP-Isostearoyl Hydrolyzed SilkOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.