Five formulas. Every percentage printed on the label.

What’s in the bottle, in the number it actually is.

Fenn & Rue mixes five products in batches of 40 liters, each labeled with its active ingredient’s real concentration — 10% azelaic acid, 2% PHA, not “clinically inspired” language standing in for a number. No fragrance, no proprietary blends.

Shop the Formulary Read a batch note

Three overlapping soft-edged rose and teal blob shapes at varying opacity with a thin dark outline stroke, arranged to leave a bottle-shaped negative space between them, abstract, no rendered product.

The Formulary

Five formulas, nothing else in the line.

Layered rose and teal blob shapes forming a soft leaf-like silhouette with a thin dark outline, evoking centella extract without depicting a leaf photo.

Cica Repair Serum

5% centella asiatica extract, ceramide NP

$34

Batch 118 · 5% · Mixed Jun 2

Two overlapping teal and rose blobs at differing opacity forming a rounded jar-like negative space, thin outline stroke.

Azelaic Evening Cream

10% azelaic acid, niacinamide

$38

Batch 204 · 10% · Mixed Jun 9

Small cluster of overlapping rose granule-shaped blobs suggesting an exfoliating texture, teal blob layered beneath.

PHA Weekend Exfoliant

2% gluconolactone

$28

Batch 077 · 2% · Mixed May 26

Single large teal droplet-shaped blob layered under a smaller rose blob, evoking an oil droplet in water.

Barrier Oil, Unscented

100% squalane, no additives

$26

Batch 312 · 100% · Mixed Jun 14

Three thin-layered rose and teal blobs stacked with visible outline strokes, evoking a concentrate’s density.

Overnight Peptide Concentrate

3% peptide complex

$46

Batch 145 · 3% · Mixed Jun 5

Every bottle carries its batch number on the label. Ask us for that batch’s mix notes — we keep them all.

Actives

Five actives. We’ll tell you what each one actually does.

Centella asiatica calms visible redness by supporting the skin barrier’s own repair response. Azelaic acid interrupts the pigment pathway that causes post-inflammatory dark marks. PHA (gluconolactone) exfoliates without the disrupted-barrier sting that glycolic acid causes on sensitized skin. Squalane is structurally close to skin’s own sebum, so it sits in the barrier instead of on top of it. Peptides signal collagen synthesis — slowly, over weeks, not overnight.

Fragrance ingredients across all five formulas

Batch Notes

We publish what changed, batch to batch.

Small-batch mixing means minor variation is real, not a marketing story — a batch of Cica Repair mixed in July will sit at a slightly different viscosity than one mixed in January, because centella extract itself varies by harvest. Instead of hiding that, every batch gets a public note: what changed, why, and whether it affects use. Batch 204’s note flagged a slightly higher niacinamide yield and recommended patch-testing if you’re new to the cream.

“If a batch note said ‘no change,’ we’d have stopped writing them years ago.”
— Dr. Amara Solis, formulator

“The batch tag on my Azelaic cream matched the mix date on the note they’d published three weeks earlier. That’s the first time a skincare brand’s paperwork has actually lined up.”

— Renata Iyer, verified buyer, Azelaic Evening Cream

“I patch-tested the PHA exfoliant against the 2% on the label and it behaved exactly like a 2% PHA should. No surprises, no stinging.”

— Jonah Whitfield, verified buyer, PHA Weekend Exfoliant

Routine

Three steps, most mornings. One extra, most nights.

Barrier Oil under moisturizer, most mornings. Azelaic Evening Cream at night, four to five nights a week — skip a night if skin feels tight. PHA Exfoliant once weekly, evening only. Overnight Peptide Concentrate layered under the Azelaic cream on nights you use both.

Download the Routine Card

What’s in the bottle, in the number it actually is.

Five formulas, nothing else in the line.

Five actives. We’ll tell you what each one actually does.

We publish what changed, batch to batch.

Three steps, most mornings. One extra, most nights.

Fenn & Rue — Formulary Skincare