How a daily moisturizer affects skin barrier, hydration, and microbiome in adults with sensitive skin

Inclusion Criteria:

* Adults aged 18 to 55 years, inclusive, of any sex.
* Self-declared sensitive skin affecting the body, characterized by unpleasant sensations such as burning, stinging, itching, tingling, tightness, or irritation in response to products or environmental triggers.
* Must present a TEWL value ≥15 g/m2/h on a volar forearm at the screening visit (T-7).
* Approximately 40-60% of enrolled participants should have Fitzpatrick skin types I-III, and approximately 40-60% should have Fitzpatrick skin types IV-VI.
* Must agree to complete a minimum 7-day washout period prior to baseline.
* Must agree to avoid body skincare products, moisturizers, hydrating gels, or prohibited topical products on both forearms during washout.
* Must agree to use sponsor-provided SPF 30 sunscreen on both forearms beginning at least 7 days before baseline and continuing throughout study participation.
* Must be willing and able to comply with all study requirements, including clinic visits, product use, questionnaires, and sample collection procedures.
* Must provide written informed consent prior to any study-specific procedure.
* Must be willing to apply study products twice daily (morning and evening) for 28 consecutive days and maintain diary compliance.

Exclusion Criteria:

* Pregnancy, breastfeeding, or planning pregnancy during the study.
* Active dermatologic disease on the forearms, visible scars, or tattoos that interfere with measurement.
* History of chronic inflammatory or autoimmune conditions (rheumatoid arthritis, lupus, psoriasis, IBD, ankylosing spondylitis, multiple sclerosis).
* Active cancer or cancer treatment within the past 5 years, with the exception of localized non-melanoma skin cancer.
* Diagnosis of primary or acquired immunodeficiency.
* Use of systemic corticosteroids (oral or injected) within 4 weeks pre-enrollment, or anticipated use during the study.
* Use of biologics for inflammatory conditions within 12 weeks pre-enrollment (including TNF inhibitors, IL-17 inhibitors, IL-23 inhibitors, IL-4/IL-13 inhibitors, dupilumab, lebrikizumab, tralokinumab, JAK inhibitors, and IL-1 blockers).
* Use of systemic immunosuppressants within 8 weeks pre-enrollment (methotrexate, cyclosporine, mycophenolate, azathioprine, systemic tacrolimus).
* Use of systemic antibiotics within 4 weeks pre-enrollment, or anticipated use during the study.
* Regular use of oral NSAIDs (defined as more than 2 days per week on average) within 2 weeks pre-enrollment or anticipated regular use during the study. Occasional use for acute conditions is permitted with logging.
* Daily aspirin use, including low-dose aspirin for cardiovascular prophylaxis.
* Use of topical corticosteroids, calcineurin inhibitors, or other prescription anti- inflammatory topicals on the forearms within 4 weeks pre-enrollment.
* Use of topical retinoids, alpha hydroxy acids, beta hydroxy acids, or other active exfoliants on the forearms within 4 weeks pre-enrollment.
* Active smoking (including vaping and recent cessation within 6 months).
* Heavy alcohol use, defined as more than 8 drinks per week.
* Surgery under general anaesthesia within the past 4 weeks.
* Vaccination within 2 weeks pre-enrollment.
* Excessive UV exposure (sunbathing, tanning beds) within 4 weeks pre-enrollment.
* Enrolled in another clinical trial within the 4 weeks pre-enrollment or during the study period.