R-Spider-Polypeptide-3: 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 R-Spider-Polypeptide-3?

R-Spider-Polypeptide-3 is a lab-created version of dragline silk fibroin 1, the primary structural protein spiders use to spin the strong outer threads of their webs. Scientists discovered that this silk protein not only boasts impressive mechanical strength but also a natural affinity for human skin, making it a valuable conditioning agent. To avoid relying on spiders, manufacturers insert the silk-producing gene into microbes such as yeast or bacteria. These microorganisms are grown in large fermentation tanks, then the silk protein is harvested, purified and spray-dried into a fine powder that blends easily into cosmetic bases. Because it forms an invisible, lightweight film on the skin, R-Spider-Polypeptide-3 is most often found in anti-aging serums, firming masks, daily moisturizers, eye creams and specialty treatments aimed at improving skin texture and softness.

R-Spider-Polypeptide-3’s Cosmetic Benefits/Uses

In formulas this ingredient serves one main role, skin conditioning. It helps bind moisture to the surface, smooths rough patches and leaves a soft, silky finish. By forming a breathable film it can also give skin a temporary tightened feel which makes fine lines look less noticeable, all while supporting a more supple complexion.

Who Can Use R-Spider-Polypeptide-3

Thanks to its lightweight film-forming nature and low likelihood of clogging pores, R-Spider-Polypeptide-3 suits most skin types including dry, normal, combination and oily. Sensitive skin tends to tolerate it as well because the protein lacks added fragrances, dyes or harsh solvents, though anyone with a known silk or protein allergy should proceed with caution.

The ingredient is produced entirely through fermentation of yeast or bacteria rather than harvesting from spiders, so products containing it are generally considered vegan and vegetarian friendly.

Current research shows no specific risks for pregnant or breastfeeding women when the protein is applied topically. That said, this is not medical advice and individuals who are expecting or nursing should let their healthcare provider review any skincare products they plan to use.

R-Spider-Polypeptide-3 does not make skin more sensitive to sunlight, so there is no added need for special sun precautions beyond a normal daily SPF.

Potential Side Effects/Adverse Reactions

Responses to topical R-Spider-Polypeptide-3 vary from person to person. The following points cover potential side effects or interactions, though most users will not experience them when the ingredient is properly formulated in a product.

  • Mild redness or itching
  • Transient tight feeling if skin is extremely dry
  • Contact dermatitis in individuals with a silk protein allergy
  • Stinging when applied to open cuts or compromised skin barriers

If you notice any persistent irritation or discomfort stop using the product and consult a healthcare professional.

Comedogenic Rating

Rating: 1 out of 5. R-Spider-Polypeptide-3 is a large, water-soluble protein that forms a breathable micro film rather than an occlusive layer, so it does not trap oil or dead skin cells inside pores. Because it is typically used at low concentrations and rinses off easily with normal cleansing, the likelihood of it triggering blackheads or whiteheads is minimal. In most formulas it is paired with lightweight solvents or humectants, further reducing the chance of congestion.

Suitable for acne-prone skin in the vast majority of cases.

One thing to note is that the overall comedogenicity of a finished product depends on every ingredient in the mix, so look at the full label if you are highly breakout sensitive.

Summary

R-Spider-Polypeptide-3 is a lab-grown spider silk protein that conditions skin by binding water, smoothing texture and leaving a soft, silky finish. It performs these tasks by creating an ultra thin, flexible film that helps hold moisture on the surface while giving a temporary firming feel.

While not yet as common as classics like hyaluronic acid, this biotech ingredient is steadily popping up in niche serums and masks thanks to its clean-label appeal and pleasant skin feel.

Current evidence shows it to be well tolerated for most skin types with a very low risk of clogging pores or causing irritation. Still, skin can be unpredictable, so patch test any new product containing R-Spider-Polypeptide-3 on a small area first to make sure it agrees with you.

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