The goal of this clinical trial is to assess how micellar water affects the skin barrier in healthy adult volunteers. The main questions it aims to answer are:

• Does leaving micellar water on the skin affect skin barrier function differently than rinsing it off?
• Are there measurable differences in transepidermal water loss (TEWL), skin hydration, and erythema between the two application methods?

Researchers will compare the effects of micellar water left on the skin versus rinsed off after application.

Participants will:

• Be randomly assigned to one of two groups
• Apply micellar water to their forehead once daily for 21 days
• Either leave the micellar water on or rinse it off, depending on their group
• Undergo non-invasive measurements of TEWL, skin hydration, and erythema before and after the intervention

Inclusion Criteria:

• Healthy adult volunteers aged 18 years and older. Willingness and ability to comply with study procedures. Signed informed consent indicating understanding of study participation, rights, and potential risks and benefits. No current skin diseases or conditions at the test site. Ability to attend all study visits and follow instructions

Exclusion Criteria:

• Participants with skin diseases, skin cancers, or sun damage at the test site will be excluded. Use of immunomodulators, corticosteroids, or antihistamines within 30 days prior to the study start is exclusionary. Application of emollient creams within 3 days before the trial is not permitted. Other exclusion criteria include protocol non-compliance, excessive exposure to natural or artificial ultraviolet radiation, pregnancy or lactation, history of vitiligo, melasma, or other hyperpigmentation or photosensitive disorders, immunosuppression, and allergy to any ingredient of the micellar solution used in the intervention. Before starting the study, participants will be asked if they have ever experienced adverse reactions to any components of the micellar solution.