Hydrolyzed Kuroda’s Sea Hare Extract: 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 30, 2025
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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 Hydrolyzed Kuroda’s Sea Hare Extract?

Hydrolyzed Kuroda’s Sea Hare Extract comes from Aplysia kurodai, a type of sea hare that lives in coastal waters around Japan and Korea. When the animal’s body is soaked in a gentle solvent, the proteins, sugars and minerals dissolve into a liquid extract. This liquid is then broken apart by enzymes or a mild acid in a process called hydrolysis, which cuts the large proteins into smaller pieces called peptides and amino acids. These smaller fragments blend smoothly into skin care formulas and can be absorbed more easily by the skin.

The use of marine ingredients in beauty dates back to traditional Asian bathing rituals. As modern brands looked for ocean sourced actives, researchers found that sea hare proteins, once hydrolyzed, left skin feeling soft and comfortable. Over the past decade the ingredient has moved from niche spa lines to mainstream products sold worldwide.

You are most likely to see Hydrolyzed Kuroda’s Sea Hare Extract in moisturizers, anti aging serums, soothing creams, sheet masks and after sun gels. Its lightweight texture makes it easy to add to both water based gels and richer emulsions.

Hydrolyzed Kuroda’s Sea Hare Extract’s Cosmetic Benefits/Uses

In formulas this marine extract mainly cares for the skin’s surface and keeps it feeling supple.

  • Skin Conditioning: The peptides and amino acids sit on the skin, helping it feel smoother and look more even. Over time they can support a healthy moisture balance, giving the complexion a fresher appearance.
  • Emollient: The extract forms a light, silky film that softens rough spots and reduces the tight feeling that can come with dryness. This makes creams glide on better and leaves a velvety finish.

Who Can Use Hydrolyzed Kuroda’s Sea Hare Extract

This ocean derived ingredient suits most skin types including dry, normal, combination, oily and sensitive because it is lightweight and non greasy. Those with very reactive or allergy prone skin should take extra care since it is sourced from a marine animal and could trigger an unexpected response.

Because the extract comes from a sea hare it is not suitable for vegans or strict vegetarians who avoid animal derived ingredients. Consumers who seek cruelty free options should confirm the brand’s harvesting and sustainability practices before purchase.

Current data shows no special concerns for women who are pregnant or breastfeeding when the extract is used in a standard cosmetic formula, yet there are no large clinical studies on this demographic. This is not medical advice and pregnant or nursing women should run any skincare products they are using past a doctor just to be on the safe side.

The extract does not make skin more sensitive to sunlight so it is unlikely to increase the risk of sunburn. Regular daily sunscreen is still recommended for overall skin health.

Potential Side Effects/Adverse Reactions

Side effects and reactions to the topical application of Hydrolyzed Kuroda’s Sea Hare Extract can vary from person to person. The following outlines potential issues but they are not expected to be the typical user experience. When the ingredient is used correctly in a well formulated product most people notice only its skin softening benefits.

  • Mild redness or warmth on the application area
  • Temporary stinging or tingling when applied to compromised skin
  • Itching or small bumps in individuals with shellfish or mollusk allergies
  • Contact dermatitis in those extremely sensitive to marine proteins

If you experience any of the above reactions discontinue use and consult a healthcare professional or dermatologist for advice.

Comedogenic Rating

Comedogenic rating: 1/5. Hydrolyzed Kuroda’s Sea Hare Extract is largely made of water soluble peptides and amino acids that rinse cleanly off the skin so they rarely block pores. It is therefore suitable for people who break out easily.

Keep in mind that finished products may pair the extract with heavier oils or waxes, which can raise the overall pore clogging risk. Always consider the full formula when shopping for acne friendly options.

Summary

Hydrolyzed Kuroda’s Sea Hare Extract acts as a skin conditioner and a light emollient. Its small peptides draw in a bit of surface moisture while the thin film they create softens rough areas and leaves skin feeling supple.

Although still a niche marine active, its presence is climbing as brands search for fresh ocean ingredients to set their formulas apart.

The extract has a strong safety profile with only isolated reports of irritation in people allergic to marine proteins. Even so, it is smart to patch test any new product that contains it to make sure your skin stays happy.

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