Why testing on melanin-rich skin matters: the gap in cosmetic research 👉🏾

Most skincare is tested on a limited range of skin types. Theresults are then applied to everyone.

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Most cosmetic testing is conducted on a limited range of skin types.

Historically, clinical studies and safety tests have relied heavily on lighter phototypes, with results often generalized across all populations.

However, melanin-rich skin can differ in barrier function, hydration, and response to irritation.

This means results observed in one group may not fully translate to another.

Inclusive testing across phototypes is not only a matter of representation. It is a matter of accuracy.

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Skincare testing is not always representative

In cosmetic development, products are evaluated through tolerance tests, patch tests, and efficacy studies.

These tests are essential. But the populations they are conducted on are not always diverse.

Studies in dermatology have consistently shown that patients with skin of color are underrepresented in clinical research, and that race and ethnicity data are often incomplete or not reported.

As a result, product performance is frequently assessed within a limited range of skin responses.

Why results are often extrapolated

Once a product has been tested, its results are often generalized across all skin types.

This assumes that barrier function, irritation response, and visible signs of reaction behave similarly across populations.

However, research suggests that this is not always the case.

Melanin-rich skin can respond differently to irritation, inflammation, and barrier disruption.

What is tested is not always what is experienced.

The challenge of measuring irritation

One of the most important limitations in testing lies in how irritation is assessed.

Patch testing, a standard method used to evaluate skin reactions, relies heavily on the detection of visible redness.

In lighter skin, erythema is easier to detect and quantify.

In melanin-rich skin, irritation may appear differently. It can be less visible, or present as darker, violaceous, or subtle changes in tone.

This does not mean that irritation is less frequent. It means it may be less visible.

In some datasets, Black patients represent less than 5 percent of patch-tested populations, despite being a much larger share of the population.

In addition, studies suggest that borderline reactions are less likely to be detected in darker skin tones, increasing the risk of underdiagnosis.

Differences that matter in practice

Research on skin of color highlights several factors that can influence how products perform:

• variations in lipid composition and barrier behavior
• differences in hydration and water retention
• increased likelihood of post-inflammatory hyperpigmentation

This last point is particularly important.

Even mild irritation, if not properly identified during testing, can lead to visible marks over time.

In melanin-rich skin, the consequences of irritation are not always immediate. They are often long-lasting.

A broader issue in dermatology

The lack of diversity in cosmetic testing reflects a wider pattern in dermatology.

Studies show that only a limited proportion of dermatological images and training materials include darker skin tones.

This contributes to lower diagnostic accuracy and a reduced ability to recognize skin conditions across all phototypes.

Dermatology has made progress in recent years, but important gaps remain in both research and clinical practice.

⏱️ What you should remember

Most testing is conducted on a limited range of skin types
Results are often generalized across all phototypes
Melanin-rich skin may respond differently and is less visible in testing

Show me the research !

This is not marketing. It is supported by dermatological research.

Studies have shown that patients with skin of color are underrepresented in clinical dermatology research, and that race and ethnicity data are often incomplete.

Patch testing data in North America indicates that Black patients represent less than 5 percent of tested populations.

Research also highlights that erythema-based evaluation methods may not fully capture irritation in melanin-rich skin, increasing the risk of underdiagnosis.

In addition, studies show that darker skin tones are underrepresented in dermatological training materials, contributing to disparities in diagnosis and understanding.

Together, these findings support the need for more inclusive testing and evaluation methods.

Why this matters

If testing does not reflect the diversity of skin types, results may not fully apply to everyone.

For melanin-rich skin, this can mean:

• underestimated irritation
• unexpected sensitivity
• higher risk of visible marks after product use

Inclusive testing is not only about representation. It is about precision.

Why K+BROWN prioritizes inclusive testing

At K+BROWN, we believe that skincare should be tested on the skin it is designed for.

That means considering multiple phototypes, different barrier behaviors, and diverse skin responses.

The goal is not only to confirm safety, but to ensure that performance is consistent across skin types.

Because skincare should not rely on assumptions.

Sources

American Contact Dermatitis Society. Position statement on dermatitis in skin of color.
Journal of Clinical and Aesthetic Dermatology. Patch testing in Black and white patients.
Journal of Drugs in Dermatology. Racial and ethnic variations in skin barrier function.
Cureus. Diagnostic disparities in dermatology across skin tones.
Dermatology journals on erythema detection and skin of color.

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