Changes in skin barrier function following long-term treatment with moisturizers, a randomized controlled trial

Area of Science:

• Dermatology
• Cosmetic Science
• Skin Physiology

Background:

• Moisturizers are widely used for dry skin and by individuals with healthy skin.
• Short-term studies indicate moisturizers can alter skin barrier function and recovery.
• Limited research exists on the long-term effects of moisturizers on skin barrier integrity.

Purpose of the Study:

• To evaluate the long-term impact of various moisturizer formulations on normal skin barrier function.
• To assess changes in transepidermal water loss (TEWL) and irritant susceptibility.
• To correlate observed effects with the specific ingredients of the experimental moisturizers.

Main Methods:

• Seventy-eight volunteers were randomized to apply specific cream or gel formulations to their forearms for seven weeks.
• Transepidermal water loss (TEWL), skin capacitance, and blood flow were measured.
• Skin susceptibility to sodium lauryl sulfate (SLS) irritation was assessed via patch testing post-treatment.

Main Results:

• Seven weeks of treatment altered normal skin barrier function.
• Simplified creams and lipid-free gels elevated TEWL and SLS-induced irritation.
• An ordinary cream containing 5% urea demonstrated opposite effects, improving barrier function and reducing TEWL.

Conclusions:

• Moisturizer composition significantly influences skin barrier function.
• Specific ingredients determine whether a moisturizer strengthens or weakens the skin barrier.
• Further research is needed to identify key ingredients and elucidate molecular mechanisms.