Fitzpatrick Skin Phototype Is Independently Associated with Differential Short-Term Cutaneous Reactivity Following...

Area of Science:

• Dermatology
• Human Physiology
• Skin Biology

Background:

• Human skin reactivity shows significant individual variability.
• The role of constitutional pigmentation, like Fitzpatrick skin phototype, in short-term skin responses is not fully understood.
• Fitzpatrick skin phototype may modify early cutaneous reactivity after topical exposure.

Purpose of the Study:

• To investigate the association between Fitzpatrick skin phototype and short-term cutaneous reactivity.
• To assess how different skin phototypes respond to standardized topical provocation.
• To determine the influence of pigmentation on dermatological testing and safety assessments.

Main Methods:

• A controlled study involving 239 healthy volunteers stratified by Fitzpatrick skin phototype (I-II, III, IV-V).
• Standardized emulgel-based topical provocation applied under occlusion to the volar forearm.
• Cutaneous responses assessed visually at 20 minutes, 24 hours, and 96 hours, with statistical analysis including multivariable regression.

Main Results:

• Significant differences in early and short-term cutaneous responses were observed across phototypes.
• Phototypes I-II showed higher response scores at 20 min and 24 h compared to phototype III (p < 0.001).
• Phototype III demonstrated independently associated lower reactivity at 20 min and 24 h; responses in phototypes IV-V were minimal but this group was underrepresented. Age predicted response intensity, sex did not. No persistent reactions at 96 h.

Conclusions:

• Fitzpatrick skin phototype is independently linked to early and short-term cutaneous reactivity.
• Lighter skin types (I-II) are more susceptible to transient inflammatory responses.
• Phototype III exhibits reduced reactivity, highlighting skin phototype's role in modifying responses for dermatological testing and safety evaluations.