Dermatologist-Reviewed Library

Skincare Guides, Decoded by Dermatologists

Long-form routines, ingredient science, and step-by-step protocols for acne, aging, and hydration — written by board-certified dermatologists and reviewed by our clinical team.

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Featured Guide
Acne · 18 min read

The Dermatologist's Guide to Fungal Acne vs. Hormonal Acne: How to Tell the Difference and Treat It Right

Most acne is not created equal. Two breakouts that look nearly identical on the surface can require opposite treatments — and using the wrong active can actually make things worse. This guide breaks down the visual cues, triggers, and clinical protocols for both fungal folliculitis and hormonal acne, with a printable routine you can take to your next derm appointment.

Dr. Naomi Park, MD Updated Nov 2025 18 min read
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Latest From The Library

Recent Skincare Guides

Evidence-based protocols and explainers, organized by skin concern. Every guide cites peer-reviewed research and is reviewed by a board-certified dermatologist before publication.

Aging

Retinoids Demystified: From Retinol to Tretinoin

Why some retinoids take six months to show results while others work in two weeks — a clear comparison of retinol, retinaldehyde, adapalene, and prescription tretinoin, including how to start without the dreaded "retinization" period.

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Hydration

The 7-Layer Hydration Method: A Clinically-Backed Routine

The Korean technique, but with dermatologist reasoning. We break down each layer, what it actually does to your stratum corneum, and how to adapt it for oily, dry, and combination skin types without clogging pores.

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Acne

Why Your Purging Isn't Working: A Salicylic Acid Protocol

Purging is a myth in most cases. If your skin is "breaking out" after starting a BHA, you may be over-exfoliating or using the wrong concentration. Here's the salicylic acid protocol our derms actually recommend.

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Aging

Vitamin C Concentration Guide: 5% vs 10% vs 20%

More isn't always better. L-ascorbic acid above 20% offers diminishing returns and increases irritation. Learn which concentration is right for your skin type, and why THD ascorbate might be the smarter choice.

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Hydration

Hyaluronic Acid: Why Your Hydrating Serum Isn't Working

HA needs water to work — and most people apply it to dry skin. We cover the "damp skin" rule, the difference between sodium hyaluronate and hydrolyzed HA, and why your $8 serum may outperform the $90 one.

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Routine

The Sunscreen Layering Rule Nobody Talks About

SPF 50 loses effectiveness fast when layered incorrectly. This guide explains the 2-finger rule, why your SPF drops to SPF 8 after moisturizer, and the order that actually delivers the protection on the label.

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Browse by Concern

Find Your Skincare Category

Every guide is tagged by primary concern so you can build a routine around what your skin actually needs right now.

Acne & Breakouts

14 guides

Aging & Firmness

11 guides

Hydration & Barrier

9 guides

Pigmentation

7 guides

Sensitive Skin

8 guides

Ingredient Science

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From a Featured Guide

A Sample PM Routine for Acne-Prone Skin

Pulled from our most-read guide, this is the four-step evening protocol our dermatologists recommend for adults dealing with persistent, non-cystic breakouts. Adapt the order — never skip the moisturizer.

1

Oil Cleanse First

Dissolve SPF, sebum, and pollution with a non-comedogenic oil. Massage for 60 seconds on dry skin before adding water.

2

Water-Based Cleanse

A low-pH gel or foam (4.5–5.5) lifts residue without stripping. Avoid sulfates — they raise skin pH and trigger more oil.

3

Active Treatment

Apply 2% salicylic acid or 0.025% tretinoin to bare, dry skin. Wait 5 minutes before the next layer for full absorption.

4

Moisturize + Seal

Layer a ceramide-rich moisturizer, then an occlusive balm only on dry zones. Barrier repair is what stops the breakout cycle.

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Ingredient Science

The Five Ingredients That Actually Move the Needle

The skincare market is oversaturated with novel actives, but only a handful have clinical evidence behind them. These are the five our dermatologists reach for first — and what each one actually does at the cellular level.

Browse the Full A–Z Ingredient Library
Anti-aging

Retinoids (Tretinoin, Adapalene)

Bind nuclear receptors to accelerate cell turnover, increase collagen I synthesis, and normalize keratinocyte shedding. The single most evidence-backed anti-aging active available.

Antioxidant

Vitamin C (L-Ascorbic Acid)

Neutralizes free radicals from UV exposure, inhibits tyrosinase to fade pigmentation, and is required for collagen cross-linking. Best at 10–20% with ferulic acid at pH below 3.5.

Hydration

Hyaluronic Acid

A glycosaminoglycan that holds up to 1,000× its weight in water. Pulls moisture from the air and deeper skin layers into the stratum corneum — but only when applied to damp skin.

Exfoliant

Beta-Hydroxy Acid (Salicylic)

Oil-soluble, so it penetrates pores to dissolve sebum plugs and reduce comedones. Anti-inflammatory at 1–2% and well-tolerated for daily use on acne-prone skin.

Sun protection

Broad-Spectrum SPF 30+

Filters both UVA (aging) and UVB (burning). Daily use is the single highest-ROI skincare decision — prevents 80% of visible photoaging and most skin cancers.

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