The useful model
The outermost skin layer is often compared to bricks and mortar: corneocytes sit within a lipid matrix that helps slow water loss and limit entry of irritants. The metaphor is imperfect, but it explains why both cells and lipids matter.
Barrier function changes with disease, climate, cleansing, friction, procedures, and the products layered on top. ‘Damaged barrier’ is a description, not a diagnosis.
A reset that is actually measurable
For one to two weeks, remove newly introduced actives, abrasive tools, and fragranced experiments. Use a gentle cleanser only where needed, a plain moisturizer, and sunscreen you tolerate. Track burning, tightness, flaking, and new lesions once daily.
Reintroduce one product at a time. If symptoms worsen or fail to settle, the next useful step may be diagnosis rather than more optimization.
Open the source file
These links support the claims above. Source dates, disclosures and limits are documented in the article and source list.