Most irritation is not caused by a bad product; it is caused by too many strong products used at once. Layering well is mainly a question of order, frequency and restraint.
General order of application
- Thinnest to thickest: watery toners, then serums, then creams, then oils
- Water-based before oil-based, always
- Sunscreen last in the morning, over everything else
- Allow a minute between layers so each absorbs rather than pills
Combinations to be careful with
- Retinoid plus AHA/BHA in the same session — alternate nights instead
- Multiple exfoliating acids stacked together
- Benzoyl peroxide with some retinoids — separate them morning and night
- High-strength vitamin C with strong acids for sensitive skin
Combinations that work well
- Niacinamide with almost anything, including vitamin C for most people
- Hyaluronic acid under a moisturiser to seal it in
- Ceramides and peptides alongside retinoids to support the barrier
- Azelaic acid as a gentler alternative when acids are too much
Building tolerance
Start a retinoid twice a week, applied to dry skin, buffered with moisturiser if needed. Increase only when two weeks pass with no flaking or stinging. Going slowly is faster overall, because you avoid the month lost to repairing a damaged barrier.
Signs your barrier is struggling
- Stinging from products that used to feel fine
- Tightness, flaking or a shiny, tender look
- New redness or sudden sensitivity to sunscreen
- If you see these, drop back to cleanser, moisturiser and sunscreen for two weeks
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