Glycolic Acid (AHA) + Tretinoin: not the same night
Tretinoin is prescription-strength; Glycolic Acid (AHA) isn't — a real gap in what each one asks of skin.
The fastest-penetrating AHA — strong results on texture and dark spots, with a real risk of over-exfoliating if rushed.
In practice, that small molecule size is a double-edged sword — the fastest visible results on this list, and the highest chance of overdoing it if the ramp is skipped.
Addresses: pigmentation and acne
The strongest, most direct prescription retinoid — real results, real irritation risk if rushed, prescription-only in most countries.
In practice, this is the retinoid a dermatologist typically prescribes once an over-the-counter option like retinol has already been tried and tolerated.
Addresses: oiliness, acne and pigmentation
How they compare
Between Glycolic Acid (AHA) and Tretinoin, Tretinoin is the stronger pick — it's prescription-only. Start with Glycolic Acid (AHA) first if introducing both.
They overlap on pigmentation and acne. Tretinoin alone also reaches oiliness. Worth staggering, not dropping either.
Why they conflict
Both speed up skin cell turnover and thin the outer skin layer. Used together, the combined exfoliation and increased sun sensitivity go well past what either ingredient produces alone — this is the most common cause of a "retinol burn."
The schedule that works
Both skip Sunday — the same stagger Skinzy's own routine builder applies automatically.
Want both effects without the conflict?
Rather than staggering these two, either one has real alternatives that work alongside it without the same-night restriction. See also ingredient combinations that work together.
Questions people ask
Not in the same application. Alternate nights instead: Glycolic Acid (AHA) on Monday/Wednesday/Friday, Tretinoin on Tuesday/Thursday/Saturday, both skipping Sunday.
Both speed up skin cell turnover and thin the outer skin layer. Used together, the combined exfoliation and increased sun sensitivity go well past what either ingredient produces alone — this is the most common cause of a "retinol burn."
Tretinoin — it's prescription-only. Start with Glycolic Acid (AHA) first if trying both.