AHAs (glycolic / lactic acid)

Low-pH exfoliating acids are commonly kept apart from copper peptides, since the acidic environment is thought to disturb the copper complex. Use the acid on its own evening and the peptide another time.

Some keep peptides away from low-pH acids as a precaution; the concern is theoretical for finished products.

The pH concern with peptides and acids is often repeated but not well-established; separate if your skin prefers.

Precautionary rather than established — many routines combine peptides and acids without issue.

Both are low-pH actives; layering can raise the chance of stinging for some skin. Introduce slowly or alternate.

Layering a retinoid with an exfoliating acid raises the chance of visible irritation for many people; alternating on different nights is common.

Combining exfoliating acids increases total exfoliation and the chance of over-doing it — use sparingly and not every day.

Two strong actives together can be drying or irritating for some; introduce slowly.

Bakuchiol is gentler than a retinoid but it is not inert, and stacking it with an AHA in one routine is the usual route to irritation. Alternate nights rather than layering, particularly while your skin is still adjusting to either.

Kojic acid is among the more irritating brightening ingredients, and an AHA on top of it compounds that. Alternate nights rather than layering; a stinging, reddened barrier will hold pigment longer, not clear it faster.

Generally fine; niacinamide is well tolerated alongside exfoliating acids.

Exfoliation on the nights you use it, barrier support after. Ceramides do not neutralise an AHA — they replace what aggressive exfoliation depletes, which is why they belong in the same routine rather than in a separate one.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.

We have not reviewed this combination. That means we have nothing to report about it — not that it is safe, and not that it is a problem. Treat it as an open question: introduce one new product at a time and patch-test, as you would with any unfamiliar pairing.