Ingredient review

Bis-SH-Pentapeptide-38 Porphyra 334

INCI: BIS-SH-PENTAPEPTIDE-38 PORPHYRA 334

A novel peptide-marine extract hybrid that may help protect skin from UV-related damage, but human studies are limited.

beautyskincarepeptideantioxidant

In plain English

This ingredient is a lab-made peptide (a short chain of amino acids) attached to a substance called Porphyra 334, which comes from red algae. The peptide part is designed to signal skin cells to behave more youthfully, while the algae part can absorb some UV light and act as an antioxidant. Together, they aim to reduce the visible effects of sun exposure and aging, but most of the evidence comes from lab tests, not large human studies.

Review score

Safety, usefulness, and evidence

3.8Good

3.8/ 5

Potentially useful with some tradeoffs

The evidence base is still emerging, so marketing claims deserve extra caution.

Risk flags are low for most users, though the finished product can still irritate.

Source: semi synthetic
Evidence: emerging
Irritation: low
Clogging risk: low

How reviews are scored

Quick decision guide

Useful, but context matters

Bis-SH-Pentapeptide-38 Porphyra 334 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.

Step 1Start with the score, then check the irritation and clogging risk before judging Bis-SH-Pentapeptide-38 Porphyra 334.
Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
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

emerging

The ingredient may be promising, but claims should be treated more cautiously.

What it is

A semi-synthetic compound that combines a custom-designed peptide (Bis-SH-Pentapeptide-38) with Porphyra 334, a mycosporine-like amino acid (MAA) naturally found in red algae that absorbs UV radiation and has antioxidant properties.

How it works

The peptide portion is thought to mimic natural signaling molecules that encourage collagen production and skin repair. The Porphyra 334 portion absorbs UV light (especially UVA) and neutralizes free radicals generated by sun exposure, potentially reducing oxidative stress and inflammation in the skin.

Pros

Dual-action protection

Combines peptide signaling with UV-absorbing and antioxidant properties from algae, offering more than a single-function ingredient.

Low irritation potential

Generally well-tolerated at typical use levels, making it suitable for many skin types, including sensitive skin.

Cons and cautions

Limited human evidence

Most research is in vitro or on similar compounds; robust human trials are scarce, so real-world benefits are not fully proven.

High cost and rarity

This specialized ingredient is expensive and not widely used, so products containing it may be pricey and hard to find.

Best for

People looking for advanced anti-aging ingredients
Those concerned with sun damage and photoaging

Use caution if

Those with very sensitive skin (patch test recommended)
Anyone allergic to algae-derived ingredients

Usage tips

Use in a daytime routine under sunscreen for added antioxidant protection.

Pair with a stable vitamin C serum for complementary antioxidant benefits.

Store products containing this ingredient away from direct light and heat to preserve stability.

Safety summary

Based on available data, this ingredient has low irritation and comedogenic risk. However, comprehensive safety assessments are lacking due to its novelty. Patch testing is advised for first-time use.

Research notes

Porphyra 334 has been studied in vitro for UV absorption and antioxidant activity. Peptide signaling mechanisms are well-documented for other peptides, but this specific combination lacks published human trials. Evidence is emerging.

Common label clues

Typical concentration: 0.1% to 1% in leave-on products
Regulatory status: Not individually regulated by the FDA as a drug; used as a cosmetic ingredient. Safety data are limited but generally considered safe at low concentrations.
Common uses: Anti-aging serums, Day creams, Eye treatments
Environmental note: Porphyra 334 is derived from red algae, which can be sustainably farmed, but the synthetic peptide portion is lab-made, so the overall environmental footprint depends on manufacturing processes.

Good to know

Porphyra 334 is a type of mycosporine-like amino acid (MAA) that some algae use as a natural sunscreen.
The 'Bis-SH' prefix indicates the peptide has been modified with thiol groups for better stability and skin penetration.

Common questions

What is Bis-SH-Pentapeptide-38 Porphyra 334 in beauty products?

What does Bis-SH-Pentapeptide-38 Porphyra 334 do in a beauty product?

Is Bis-SH-Pentapeptide-38 Porphyra 334 safe for most people?

Who should be careful with Bis-SH-Pentapeptide-38 Porphyra 334?

Those with very sensitive skin (patch test recommended) Anyone allergic to algae-derived ingredients

Research sources

PubMed - Mycosporine-like amino acids as natural sunscreensOpen Cosmetic Ingredient Review - Peptides safetyOpen INCI Decoder - Bis-SH-Pentapeptide-38Open

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.